The function-led design of porous hydrochar from mineral-rich biowaste for environmental applications inevitably suffers from carbon-ash recalcitrance.However,a method to alter the original carbon skeleton with ash re...The function-led design of porous hydrochar from mineral-rich biowaste for environmental applications inevitably suffers from carbon-ash recalcitrance.However,a method to alter the original carbon skeleton with ash remains elusive and hinders the availability of hydrochar.Herein,we propose a facile strategy for breaking the rigid structure of carbon-ash coupled hydrochar using phase-tunable molten carbonates.A case system was designed in which livestock manure and NaHCO3 were used to prepare the activated hydrochar,and NH3 served as the target contaminant.Due to the redox effect,we found that organic fractions significantly advanced the melting temperature of Na2CO3 below 800℃.The Na species steadily broke the carbon-ash interaction as the thermal intensity increased and transformed inorganic constituents to facilitate ash dissolution,rebuilding the hydrochar skeleton with abundant hierarchical channels and active defect edges.The surface polarity and mesopore distribution collectively governed the five cycles NH3 adsorption attenuation process.Manure hydrochar delivered favorable potential for application with a maximum overall adsorption capacity of 100.49 mg·g^(-1).Integrated spectroscopic characterization and theoretical computations revealed that incorporating NH3 on the carbon surface could transfer electrons to chemisorbed oxygen,which promoted the oxidation of pyridine-N during adsorption.This work offers deep insight into the structure function correlation of hydrochar and inspires a more rational design of engineered hydrochar from high-ash biowaste.展开更多
The Response Surface Methodology (RSM) was used to optimise the conditions of preparation of activated hydrochar from tannery solid waste by hydrothermal carbonisation (HTC). The main factors such as residence time, m...The Response Surface Methodology (RSM) was used to optimise the conditions of preparation of activated hydrochar from tannery solid waste by hydrothermal carbonisation (HTC). The main factors such as residence time, moisture content and final carbonisation temperature were investigated during the optimisation of hydrochar preparation conditions. The three responses investigated are hydrochar yield, iodine and methylene blue indices. The results of experimental analyses showed that the yield of hydrochar decreases with increasing final temperature, leading to the formation of micropores inside the carbonaceous solid. The optimum conditions for preparing the following hydrochar were obtained: 83.10%, 390.44 mg∙g−1 and 259.63 mg∙g−1 respectively for the hydrochar yield, the iodine and methylene blue indices. The specific surface area of prepared hydrochar is 849.160 m2/g, SEM micrographs showed a porous heterogeneous surface and particularly, the hydrochar surface also revealed external pores on the hydrochar surface which acted as a pathway to the micropores. Fourier transform infrared (FTIR), however, showed a predominance of acid functions on the surface of the carbonaceous solids. Tests were carried out to eliminate indigo carmine in aqueous media. Activated hydrochar showed a high level of activity, with the Langmuir and Freundlich isotherms giving an adsorption quantity of 354.610 mol/g and a KF constant of 468.2489, respectively. The findings of the research revealed that hydrochar produced is well adapted for dyes removal.展开更多
Innovative measure is a urgent requirement for managing the huge volume of municipal sewage sludge. The hydrothermal carbonation （HTC） shows some potential advantages for using hydrochar as a soil conditioner. The a...Innovative measure is a urgent requirement for managing the huge volume of municipal sewage sludge. The hydrothermal carbonation （HTC） shows some potential advantages for using hydrochar as a soil conditioner. The aim of this work was to investigate the properties of hydrochars, by means of the HTC of municipal sewage sludge under different temperatures （190 and 260~C） and reaction hours （1, 6, 12, 18 and 24 h）. The HTC led to the decreases of N, O and H contents by more than 54.6, 37.9 and 10.0%, respectively, and slight changes of C content. The Py-GC-MS analysis showed that a large proportion of fatty acids, in particular hexadecanoic acid, transferred into alkenes, olefins and aromatic compounds. The 13C-NMR and fourier transform infrared spectra （FTIR） confirmed the transformation and changes in chemical structure in which hydrochar contained lower oxygen-containing organic C of O-alkyl, carboxylic and carbonyl C and aliphaticity, but higher aromatic C and aromaticity. The rich hydrophobic functions induced in high positive charges in the charred sludge. The HTC facilitated the pore structure development, proved by higher specific surface area and specific pore volume, with a maximum of 17.30 and 0.83 cm^3 g^-1, respectively. The availabilities of N, P and K markedly reduced during HTC treatment. The activities of most heavy metals were depressed though they accumulated in the hydrochar. Further work is required to investigate the values and risk of the charred sludge amended to soil.展开更多
A rising global population and aspirational higher living standards has driven a step change in resource utilization and concomitant anthropogenic pollution across the biosphere.Low-cost and scalable technologies for ...A rising global population and aspirational higher living standards has driven a step change in resource utilization and concomitant anthropogenic pollution across the biosphere.Low-cost and scalable technologies for environmental remediation are therefore urgently sought,with an emphasis on trash-to-treasure strategies that exploit abundant but underutilized waste by-products of existing sectors.Biochars are carbon-rich,porous solids produced by biomass pyrolysis under anaerobic or oxygen-scarce conditions at high temperature(350–700°C),while hydrochars are produced by hydrothermal biomass carbonization at lower temperature(130–250°C)and high autogenous pressures(0.3–4.0 MPa).Bio/hydrochars possess unique physicochemical properties,notably high surface areas(100–1500 m2 g-1)and porosity(0.25–2.5 cm^(3)g^(-1))and rich surface chemistry featuring carboxylic,phenolic,hydroxyl,and carbonyl functions,amenable to chemical,physical,or biochemical modification,rendering them ideal sorbents for pollutants such as heavy metals(e.g.As and Cr),and toxic organic(e.g.,dyes and xenobiotics)and inorganic(e.g.,SO_(2))molecules.Bio/hydrochars are attractive for environmental remediation of pollutant mixtures by surface complexation,redox chemistry,electrostatic interactions/ion exchange,or coprecipitation.This review discusses recent opportunities and challenges in creating bio/hydrochar sorbents and their nanocomposites through grafting,doping,and chemical/physical activation,for the depollution of aquatic and atmospheric environments.展开更多
In this paper,a novel compound was developed by mixing H_(3)PO_(4)-modified cauliflower leaves hydrochar(CLH)and coal gangue-based Na-X zeolite(ZL).An alkaline soil contaminated with cadmium(Cd)and lead(Pb)was amended...In this paper,a novel compound was developed by mixing H_(3)PO_(4)-modified cauliflower leaves hydrochar(CLH)and coal gangue-based Na-X zeolite(ZL).An alkaline soil contaminated with cadmium(Cd)and lead(Pb)was amended through the individual and synergistic application of CLH and ZL(1%CLH,2%CLH,1%ZL,2%ZL and 1%CLH+1%ZL),and Chinese cabbage was grown on it.Individual application of CLH was superior to ZL on decreasing the pH of alkaline soil and increasing soil available phosphorus(Olsen-P)and soil organic matter(SOM).In contrast,their combined application significantly improved the soil cation exchange capacity(CEC).Besides,the 1%CLH+1%ZL was the most efficient treatment in decreasing diethylenetriamine pentaacetate(DTPA)-extractable Cd/Pb and concentrations of these two metals in cabbage root and shoot.Their synergistic application could better increase Cd and Pb immobilization and cabbage yield than their alone application.Furthermore,the immobilization of Pb for all treatments was higher than that of Cd.The synergistic immobilization mechanism of CLH and ZL reflected that the CLH precipitated and complexed with these two metals,which may block the pores of hydrochar or wrap on the surface of hydrochar.So the continuous adsorption and complexation were prevented.Nevertheless,ZL could probably alleviate this obstacle.This finding provides helpful information about using CLH combined with ZL as a soil stabilizer to immobilize heavy metals in contaminated alkaline soil.展开更多
Hydrochar prepared with four typical biowastes,pine wood,food waste,digested sewage sludge,and Chlorella were applied for the promotion of anaerobic digestion.The gas production and substrate composition were analyzed...Hydrochar prepared with four typical biowastes,pine wood,food waste,digested sewage sludge,and Chlorella were applied for the promotion of anaerobic digestion.The gas production and substrate composition were analyzed associated with the hydrochar characteristics.The results suggested that Chlorella hydrochar(C-C)showed the highest cumulative yield of methane(approximately 345 mL)with high total organic carbon(TOC)removal efficiency and low volatile fatty acids(VAFs)concentration.Especially,food waste hydrochar(F-C)showed a poor effect on anaerobic digestion and aroused 1.4–1.6 g/L accumulation of VAFs,in which the toxic components may account for the low efficiency.The C-C and sludge hydrochar(S-C)may develop direct interspecific electron transport(DIET)to facilitate the generation of methane by both surface groups and conductivity of the body structure,unlike pinewood hydrochar(P-C),which mainly depended on the aromatic matrix structure of hydrochar body.This work suggested that C-C can be the best candidate for the facilitation of anaerobic digestion,and N-containing biowaste like algae and lignocellulose like pine wood may establish different DIET pathways based on the physicochemical characteristics of hydrochar.展开更多
Hydrothermal carbonization is highly applicable to high moisture biomass upgrading due to the fact that moist-ure involved can be directly used as reaction media under the subcritical-water region.With this,value-adde...Hydrothermal carbonization is highly applicable to high moisture biomass upgrading due to the fact that moist-ure involved can be directly used as reaction media under the subcritical-water region.With this,value-added utilization of hydrochar as solid fuel with high carbon and energy density is one of the important pathways for biomass conversion.In this review,the dewatering properties of hydrochar after the hydrothermal carbonization of biowaste,coalification degree with elemental composition and evolution,pelletization of hydrochar to enhance the mechanical properties and density,coupled with the combustion properties of hydrochar biofuel were discussed with various biomass and carbonization parameters.Potential applications for the co-combustion with coal,cleaner properties and energy balance for biowaste hydrothermal carbonization were presented as well as the challenges.展开更多
The corncob hydrochar is prepared by using a stainless autoclave at 230?C for 8 h.The products are characterized by elemental analyzer,Fourier Transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and scanning ...The corncob hydrochar is prepared by using a stainless autoclave at 230?C for 8 h.The products are characterized by elemental analyzer,Fourier Transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and scanning electron microscope(SEM).The effects of hydrochar dosage,pH,adsorption time and phenol concentration on the adsorption performance of hydrochar are investigated by means of single-factor experimental analysis.Based on the experiments the adsorption thermodynamic and kinetics are tentatively discussed.The results show that abundant oxygen-containing functional groups are scattered on the surface of the corncob hydrochar.The adsorption kinetics of phenol on the hydrochar corresponds well with pseudo-second-order kinetic model.Thermodynamic studies indicate that Freundlich adsorption isotherm model is much better than Langmuir model in describing the adsorption of phenol on the corncob hydrochar at 25?C-45?C.This study provides scientific basis for the development of cheap and efficient adsorbents for the removal of phenols derived from oilfield wastewater.展开更多
Lignin,an abundant aromatic polymer in nature,has received significant attention for its potential in the production of bio-oils and chemicals owing to increased resource availability and environmental issues.The hydr...Lignin,an abundant aromatic polymer in nature,has received significant attention for its potential in the production of bio-oils and chemicals owing to increased resource availability and environmental issues.The hydrodeoxygenation of guaiacol,a lignin-derived monomer,can produce cyclohexanol,a nylon precursor,in a carbon-negative and environmentally friendly manner.This study explored the porous properties and the effects of activation methods on the Ru-based catalyst supported by environmentally friendly and cost-effective hydrochar.Highly selective cleavage of C_(ary)-O bonds was achieved under mild conditions(160°C,0.2 MPa H_(2),and 4 h),and alkali activation further improved the catalytic activity.Various characterization methods revealedthat hydrothermal treatment and alkali activation relatively contributed to the excellent performance of the catalysts and influenced their porous structure and Ru dispersion.X-ray photoelectron spectroscopy results revealed an increased formation of metallic ruthenium,indicating the effective regulation of interaction between active sites and supports.This synergistic approach used in this study,involving the valorization of cellulose-derived hydrochar and the selective production of nylon precursors from lignin-derived guaiacol,indicated the comprehensive and sustainable utilization of biomass resources.展开更多
This study investigates the simultaneous production of hydrochar and bioactive compounds from Ulva lactuca via a hydrothermal process.The experiment was carried out using a batch reaction vessel at different reaction ...This study investigates the simultaneous production of hydrochar and bioactive compounds from Ulva lactuca via a hydrothermal process.The experiment was carried out using a batch reaction vessel at different reaction temperatures of 180-220◦C and various holding times of 30-90 min.As expected,both temperature and time vigorously influenced hydrochar and bioactive compound production.The maximum hydrochar yield was at 32.4 wt%.The higher heating value(HHV)of hydrochar was observed in the range of 17.68-21.07 MJ kg^(-1),near the energy content of low-rank coals.The hydrochars exhibited contact angles higher than 90°(i.e.,94-108°)for a longer time,confirming their hydrophobic surfaces.The scanning electron microscope analysis(SEM)showed that the hydrothermal process enables cracks in the spherical shape of raw U.lactuca into small and porous particles.Besides producing hydrochar,the hydrothermal process of U.lactuca also gives promising antioxidants and phenolics as bioactive compounds.The highest total phenolic content and antioxidant activity could be achieved in hydrolysate at 200℃and 30 min with the value of 1.20±0.12 mg/g and 71.6±1.3%,respectively.展开更多
Hydrothermal treatment(HTT)can efficiently valorize the digestate after anaerobic digestion.However,the disposal of the HTT liquid is challenging.This paper proposes a method to recover energy through the anaerobic co...Hydrothermal treatment(HTT)can efficiently valorize the digestate after anaerobic digestion.However,the disposal of the HTT liquid is challenging.This paper proposes a method to recover energy through the anaerobic co-digestion of food waste and HTT liquid fraction.The effect of HTT liquid recirculation on anaerobic co-digestion performance was investigated.This study focused on the self-generated hydrochars that remained in the HTT supernatant after centrifugation.The effect of the self-generated hydrochars on the methane(CH_(4))yield and microbial communities were discussed.After adding HTT liquids treated at 140 and 180C,the maximum CH4 production increased to 309.36 and 331.61 mL per g COD,respectively.The HTT liquid exhibited a pH buffering effect and kept a favorable pH for the anaerobic co-digestion.In addition,the self-generated hydrochars with higher carbon content and large oxygen-containing functional groups remained in HTT liquid.They increased the electron transferring rate of the anaerobic co-digestion.The increased relative abundance of Methanosarcina,Syntrophomonadaceae,and Synergistota was observed with adding HTT liquid.The results of the principal component analysis indicate that the electron transferring rate constant had positive correlationships with the relative abundance of Methanosarcina,Syntrophomonadaceae,and Synergistota.This study can provide a good reference for the disposal of the HTT liquid and a novel insight regarding the mechanism for the anaerobic co-digestion.展开更多
The hydrothermal carbonization(HTC)of biogas digestate alters the raw materials inherent characteristics to produce a carbon(C)-rich hydrochar(HC),with an improved suitability for soil amelioration.Numerous studies re...The hydrothermal carbonization(HTC)of biogas digestate alters the raw materials inherent characteristics to produce a carbon(C)-rich hydrochar(HC),with an improved suitability for soil amelioration.Numerous studies report conflicting impacts of various HC application rates on soil properties and plant growth.In this study,the influence of HC application rate on soil improvement and plant growth aspects was investigated in three diverse soils(Chernozem,Podzol,and Gleysol).Pot trials were conducted in which all soils were amended with 5,10,20 and 30%(w/w)HC in quintuplicate,with two controls of pure soil(with and without plants,respectively)also included.Prior to potting,soil samples were collected from all HC-amended soils and controls and analyzed for soil pH,plant available nutrients(PO4-P and K),and microbial activity using standard laboratory and statistical methods.Immediately after potting,a 6-week seed germination experiment using Chinese cabbage was conducted to determine germination success,followed by a plant growth experiment of equal duration and plant species to determine biomass success.At the end of the study(after a total plant growth period of 12 weeks),each pot was sampled and comparatively analyzed for the same soil properties as at the beginning of the study.Soil pH shifted toward the pH of the HC(6.6)in all soils over the course of the study,but was most expressed in the 20%and 30%application rates,confirming the well-documented liming effect of HC.The addition of HC increased the PO4-P and K contents,particularly with 20%and 30%HC amendments.These results are proposedly due to the large labile C fraction of the HC,which is easily degradable by microorganisms.The rapid decomposition of this C fraction prompted the quick release of the HCs inherently high PO4-P and K content into the soil,and in turn,further stimulated microbial activity,until this fraction was essentially depleted.HC addition did not inhibit seed germination at any rate,presumably due to a lack of phytotoxic compounds in the HC from aging and microbial processes,and furthermore,showed no significant impact(positive or negative)on plant growth in any soil,despite improved soil conditions.In conclusion,although less pronounced,soil improvements were still achievable and maintainable at lower application rates(5%and 10%),whereas higher rates did not ensure greater benefits for plant growth.While the addition of high rates of HC did not detrimentally effect soil quality or plant growth,it could lead to leaching if the nutrient supply exceeds plant requirements and the soil’s nutrient retention capacity.Therefore,this study validates the previous study in the effectiveness of the biogas digestate HC for soil amelioration and suggests that smaller regularly repeated HC applications may be recommendable for soil improvement.展开更多
Hydrothermal carbonization(HTC)technology has increasingly been considered for biomass conversion applications because of its economic and environmental advantages.As an HTC conversion product,hydrochar has been widel...Hydrothermal carbonization(HTC)technology has increasingly been considered for biomass conversion applications because of its economic and environmental advantages.As an HTC conversion product,hydrochar has been widely used in the agricultural and environmental fields for decades.A CiteSpace-based system analysis was used for conducting a bibliometric study to understand the state of hydrochar environmental application research from 2011 to 2021.Researchers had a basic understanding of hydrochar between 2011 and 2016 when they discovered hydrochar could apply to agricultural and environmental improvement projects.Keyword clustering results of the literature published in 2017-2021 showed that soil quality and plant growth were the major research topics,followed by carbon capture and greenhouse gas emissions,organic pollutant removal,and heavy metal adsorption and its bioavailability.This review also pointed out the challenge and perspective for hydrochar research and application,namely:(1)the environmental effects of hydrochar on soils need to be clarified in terms of the scope and conditions;(2)the influence of soil microorganisms needs to be investigated to illustrate the impact of hydrochar on greenhouse gas emissions;(3)combined heavy metal and organic contaminant sorption experiments for hydrochar need to be conducted for large-scale applications;(4)more research needs to be conducted to reveal the economic benefits of hydrochar and the coupling of hydrochar with anaerobic digestion technology.This review suggested that it would be valuable to create a database that contains detailed information on how hydrochar got from different sources,and different preparation conditions can be applied in the environmental field.展开更多
To realize the synergistic treatment of dairy cow manure solids and dairy cattle breeding sewage,this study produced phosphorus-modified hydrochar by dairy cow manure solids impregnated with potassium phosphate(K_(3)P...To realize the synergistic treatment of dairy cow manure solids and dairy cattle breeding sewage,this study produced phosphorus-modified hydrochar by dairy cow manure solids impregnated with potassium phosphate(K_(3)PO_(4)).And then,the adsorption characteristics of Cu(Ⅱ)and ammonium(NH_(4)^(+))in dairy cattle breeding sewage under different dosages and adsorption time conditions of modified hydrochar were explored.The results show that the specific surface area and total pore volume of the hydrochar were increased by phosphorus-modified.The adsorption amount of hydrochar per unit-mass decreased with the increase in the dosage.With the increase in the dosage,the adsorption capacity of Cu(Ⅱ)decreased from the initial 26.16 mg/g to 3.38 mg/g.The adsorption of Cu(Ⅱ)and NH_(4)^(+)in sewage by hydrochar was mainly chemical adsorption,which was mainly affected by chelation and ion exchange.This adsorption was more inclined to single-molecular layer adsorption.Both the pH values and the ionic strength influenced the competitive adsorption between Cu(Ⅱ)and NH_(4)^(+).The higher the pH value was,the greater the adsorption amount,and the stronger the adsorption capacity by hydrochar.Moreover,the increase in the ionic strength decreases the adsorption capacity of hydrochar.展开更多
Hydrochar has potential applications in soil improvement and heavy metal remediation.Hydrochar would undergo the process of aging when introduced into the soil,altering its properties.However,recent studies have focus...Hydrochar has potential applications in soil improvement and heavy metal remediation.Hydrochar would undergo the process of aging when introduced into the soil,altering its properties.However,recent studies have focused mainly on the artificial aging of hydrochar,which could not reveal the cumulative effect of multiple environmental factors.Therefore,the periodical monitoring of the property and sorption behavior of hydrochar after amending soils is necessary to better understand the multifaceted mechanisms associated with the natural aging of hydrochar.This study selected the sludge-derived hydrochar(SLHC)as a typical hydrochar and applied a 16-month rice-wheat-rice rotation to mimic the natural aging of hydrochar,focusing on changing properties and cadmium(Cd)sorption and literature contrast between aging strategies and biochar types.The porosity,O abundance,and ash content of 16-month aged SLHC increased by 37%,47%,and 8.5%,respectively,facilitating Cd sorption due to surface complexation,pore sorption,and precipitation.The sorption percentage of Cd to SLHC was in the range of 11-14%for SLHC-A0 and increased to 17-31%for SLHC-A4 and 20-32%for SLHC-A16 after natural aging.The natural aging of SLHC induced by ash content played an essential role in Cd sorption site heterogeneity.Linear regression analysis showed that aging strategies on sorption behavior significantly differed between biochars.Thus,studies involving natural aging with multiple environmental factors are preferred over those involving chemical or biological aging.Future studies should continue to explore the mechanisms of natural aging-induced heavy metal sorption between hydrochar and pyrochar.These results improve insights to appraise the potential of SLHC as soil amendments to alleviate the adverse effects of heavy metal contamination and provide an essential basis for researchers and staff in soil management and environmental prevention.展开更多
Hydrochar(HC)produced by the hydrothermal carbonization(HTC)of typically wet biomass is generally considered to be less effective for carbon(C)sequestration in soils compared to biochar(BC)by pyrolysis,due to a higher...Hydrochar(HC)produced by the hydrothermal carbonization(HTC)of typically wet biomass is generally considered to be less effective for carbon(C)sequestration in soils compared to biochar(BC)by pyrolysis,due to a higher content of more easily decomposable C.Although the recalcitrance of HC is suggested to improve with increasing HTC production temperature,the way it interacts and becomes associated with soil organic matter(SOM)fractions of different stabilities against decomposition,may also influence its effectiveness for C sequestration in soils.In that respect,this study aimed to verify the potential of HCs from maize silage produced at different HTC temperatures(190,210 and 230℃)for C sequestration in a HC-amended sandy loam Podzol.To do this,we conducted a pot trial experiment and traced the fate of HC-derived C(HC-C)within different SOM fractions,namely the free-and occluded particulate organic matter(POMF and POMO,respectively)fractions and that comprising organic matter(OM)bound to clays(OMCl).Approx.1 year after applying 5%of the different HTC temperature HCs to the soil,the SOM fractions were isolated by density fractionation for each HC treatment(HC190,HC210 and HC230)and the control(absent of HC).All fractions and the HCs were analyzed for organic C(OC)content and isotopic signatures(δ^(13)C).From the δ^(13)C signatures,the amount of HC-C and native soil organic carbon(SOC)within each fraction was calculated.Increased C contents and decreased H/C and O/C ratios were observed with increasing HTC production temperatures,which sug-gests a lower stability for the low temperature HC.After ca.1 year,a loss of~20-23%of the bulk soil TOC was found in the HC-amended soils.The POMF fraction of the HC-amended soils showed losses of 68-81%HC-C and 52-72%native SOC,which may be due to a positive priming effect caused by HC addition.The POM_(O) and OM_(Cl) fractions of the HC-amended soils contained more OC than the control,indicating the integration of HC-C together with SOM within these more stable fractions,while the effect of HTC production temperature on the level of decomposition of the resultant HCs was negligible.In all HC treatments,the OM_(Cl) fraction comprised the least amount of HC-C,thus showing the weakest response to C amendment.In conclusion,long(er)-term research on the C net balance that accounts for the observed priming-induced TOC losses and the HC-C enrichment in more stable fractions is required to verify the potential of the different HCs for the purpose of C sequestration in soils.展开更多
The cellulose-based hydrogel has been widely applied for soil water retention and nutrient re-lease agents for several decades.Embedding the inorganic materials into hydrogels is an excellent strategy to improve the i...The cellulose-based hydrogel has been widely applied for soil water retention and nutrient re-lease agents for several decades.Embedding the inorganic materials into hydrogels is an excellent strategy to improve the inherent limits of the cellulose-based hydrogel.Notably,municipal sludge-derived hydrochar(HC)has reduced the environmental burden and offered a potential hydrogel carrier to control water-retention and nutrient-release.However,the above function for plant growth of hydrochar-embedded carboxymethyl cellulose-g-poly(acrylic acid)(CMC-g-PAA/HC)is unknown,and relevant reports are lacking.This study investigated the water retention,nutri-ent release behavior,and effect of germination and plant growth of CMC-g-PAA/HC hydrogel.Characterization results showed that HC was successfully incorporated into CMC-g-PAA/HC with 6.0%higher thermostability,7.2-21.0%lower swelling ratio(SR)in water,and substantial SR in phosphate solution(P-solution).The water loss rate of CMC-g-PAA/HC in P-solution or wa-ter owned a more significant temperature response(7.9-15.0 folds)than CMC-g-PAA(8.2-10.0 folds).Moreover,4.0%higher n value and more 18.5%released P for CMC-g-PAA/HC were also observed.These phenomena were due to restricting the polymer chains movement and the wa-ter molecules diffusion inside the hydrogels with HC.Phytotoxicity assessments showed that HC in CMC-g-PAA/HC could effectively alleviate the inhibition effects on rape germination retained with 78.3%germination vigor and 80.0%germination ratio,even dramatically improved plant growth to 28 d.The results of this study demonstrated a new route for developing eco-friendly CMC-g-PAA/HC hydrogel,advantageous as a water retention agent and nutrient carrier in arid and semiarid regions.展开更多
Hydrochar(HC),produced by hydrothermal carbonization,offers technical advantages over biochar(BC)produced by pyrolysis,and is suitable for soil amelioration,carbon sequestration,and enhanced plant growth.BC grain size...Hydrochar(HC),produced by hydrothermal carbonization,offers technical advantages over biochar(BC)produced by pyrolysis,and is suitable for soil amelioration,carbon sequestration,and enhanced plant growth.BC grain size has been shown to influence nutrient retention,microbial colonization and aggregate formation;however,similar research for HC is lacking.Pot trials were conducted to investigate the influence of HC grain size[coarse(6.3-2 mm),medium(2-0.63 mm)and fine(<0.63 mm)],produced from biogas digestate,for soil improvement in three soils:loamy Chernozem,sandy Podzol,and clayey Gleysol,at a 5%HC application rate(w/w).All soils including two controls(with and without plants)were analysed for water holding capacity(WHC),cation exchange capacity(CEC),wet aggregate stability,pH,plant available nutrients(PO_(4)-P,K and N_(min))and germination and biomass success using standard laboratory and statistical methods.Soil pH showed a compensatory shift toward the HC pH(7.2)in all soils over the course of the study.For example,the pH of the medium grained HC treatment for the Chernozem decreased from 7.9 to 7.2 and increased in the Podzol and Gleysol from 5.9 to 6.1 and 4.9 to 5.5,respectively.The nutrient-rich HC(2034±38.3 mg kg^(−1) PO_(4)-P and 2612.5±268.7 mg kg^(−1) K content)provided only a short-term supply of nutrients,due to the relatively easily mineralized fraction of HC,which allowed for quick nutrient release.The pH and PO_(4)-P effects were most pronounced in the fine grained HC treatments,with a~87%,~308%and~2500%increase in PO_(4)-P content in the Chernozem,Podzol and Gleysol,respectively,compared to the controls at the beginning of the study.The same trend was observed for the K and NH_(4)^(+)content in the fine and medium grained HC treatments in all soils.No seed germination inhibition of Chinese cabbage was observed,with average germina-tion rates>50%in all soils.An effect on NO_(3)^(−)content was indeterminable,while there was little to no effect on biomass production,WHC,CEC and aggregate stability.In conclusion,the application of 5%fine grained HC significantly influenced the nutrient content over a short-term.However,the application rate was insufficient to substantially improve plant growth,nor to sustain a longer-term nutrients supply,regardless of grain size.展开更多
基金supported by the National Natural Science Foundation of China(52261145701 and U21A20162)the 2115 Talent Development Program of China Agricultural University.
文摘The function-led design of porous hydrochar from mineral-rich biowaste for environmental applications inevitably suffers from carbon-ash recalcitrance.However,a method to alter the original carbon skeleton with ash remains elusive and hinders the availability of hydrochar.Herein,we propose a facile strategy for breaking the rigid structure of carbon-ash coupled hydrochar using phase-tunable molten carbonates.A case system was designed in which livestock manure and NaHCO3 were used to prepare the activated hydrochar,and NH3 served as the target contaminant.Due to the redox effect,we found that organic fractions significantly advanced the melting temperature of Na2CO3 below 800℃.The Na species steadily broke the carbon-ash interaction as the thermal intensity increased and transformed inorganic constituents to facilitate ash dissolution,rebuilding the hydrochar skeleton with abundant hierarchical channels and active defect edges.The surface polarity and mesopore distribution collectively governed the five cycles NH3 adsorption attenuation process.Manure hydrochar delivered favorable potential for application with a maximum overall adsorption capacity of 100.49 mg·g^(-1).Integrated spectroscopic characterization and theoretical computations revealed that incorporating NH3 on the carbon surface could transfer electrons to chemisorbed oxygen,which promoted the oxidation of pyridine-N during adsorption.This work offers deep insight into the structure function correlation of hydrochar and inspires a more rational design of engineered hydrochar from high-ash biowaste.
文摘The Response Surface Methodology (RSM) was used to optimise the conditions of preparation of activated hydrochar from tannery solid waste by hydrothermal carbonisation (HTC). The main factors such as residence time, moisture content and final carbonisation temperature were investigated during the optimisation of hydrochar preparation conditions. The three responses investigated are hydrochar yield, iodine and methylene blue indices. The results of experimental analyses showed that the yield of hydrochar decreases with increasing final temperature, leading to the formation of micropores inside the carbonaceous solid. The optimum conditions for preparing the following hydrochar were obtained: 83.10%, 390.44 mg∙g−1 and 259.63 mg∙g−1 respectively for the hydrochar yield, the iodine and methylene blue indices. The specific surface area of prepared hydrochar is 849.160 m2/g, SEM micrographs showed a porous heterogeneous surface and particularly, the hydrochar surface also revealed external pores on the hydrochar surface which acted as a pathway to the micropores. Fourier transform infrared (FTIR), however, showed a predominance of acid functions on the surface of the carbonaceous solids. Tests were carried out to eliminate indigo carmine in aqueous media. Activated hydrochar showed a high level of activity, with the Langmuir and Freundlich isotherms giving an adsorption quantity of 354.610 mol/g and a KF constant of 468.2489, respectively. The findings of the research revealed that hydrochar produced is well adapted for dyes removal.
基金financially supported by the National Natural Science Foundation of China (41071206)
文摘Innovative measure is a urgent requirement for managing the huge volume of municipal sewage sludge. The hydrothermal carbonation （HTC） shows some potential advantages for using hydrochar as a soil conditioner. The aim of this work was to investigate the properties of hydrochars, by means of the HTC of municipal sewage sludge under different temperatures （190 and 260~C） and reaction hours （1, 6, 12, 18 and 24 h）. The HTC led to the decreases of N, O and H contents by more than 54.6, 37.9 and 10.0%, respectively, and slight changes of C content. The Py-GC-MS analysis showed that a large proportion of fatty acids, in particular hexadecanoic acid, transferred into alkenes, olefins and aromatic compounds. The 13C-NMR and fourier transform infrared spectra （FTIR） confirmed the transformation and changes in chemical structure in which hydrochar contained lower oxygen-containing organic C of O-alkyl, carboxylic and carbonyl C and aliphaticity, but higher aromatic C and aromaticity. The rich hydrophobic functions induced in high positive charges in the charred sludge. The HTC facilitated the pore structure development, proved by higher specific surface area and specific pore volume, with a maximum of 17.30 and 0.83 cm^3 g^-1, respectively. The availabilities of N, P and K markedly reduced during HTC treatment. The activities of most heavy metals were depressed though they accumulated in the hydrochar. Further work is required to investigate the values and risk of the charred sludge amended to soil.
基金the National Natural Science Foundation of China(NNSFC21706134)the Young Natural Science Foundation of Jiangsu Province(BK20170918)for financial supportsupport from the“Advanced analysis and testing center of Nanjing Forestry University.”
文摘A rising global population and aspirational higher living standards has driven a step change in resource utilization and concomitant anthropogenic pollution across the biosphere.Low-cost and scalable technologies for environmental remediation are therefore urgently sought,with an emphasis on trash-to-treasure strategies that exploit abundant but underutilized waste by-products of existing sectors.Biochars are carbon-rich,porous solids produced by biomass pyrolysis under anaerobic or oxygen-scarce conditions at high temperature(350–700°C),while hydrochars are produced by hydrothermal biomass carbonization at lower temperature(130–250°C)and high autogenous pressures(0.3–4.0 MPa).Bio/hydrochars possess unique physicochemical properties,notably high surface areas(100–1500 m2 g-1)and porosity(0.25–2.5 cm^(3)g^(-1))and rich surface chemistry featuring carboxylic,phenolic,hydroxyl,and carbonyl functions,amenable to chemical,physical,or biochemical modification,rendering them ideal sorbents for pollutants such as heavy metals(e.g.As and Cr),and toxic organic(e.g.,dyes and xenobiotics)and inorganic(e.g.,SO_(2))molecules.Bio/hydrochars are attractive for environmental remediation of pollutant mixtures by surface complexation,redox chemistry,electrostatic interactions/ion exchange,or coprecipitation.This review discusses recent opportunities and challenges in creating bio/hydrochar sorbents and their nanocomposites through grafting,doping,and chemical/physical activation,for the depollution of aquatic and atmospheric environments.
基金This work was financially supported by the National Natural Science Foundation of China(No.21701099)the Science and Technology Innovation Project of Colleges and Universities of Shanxi Province in 2020(No.2020L0721)the Basic Research Project of Shanxi Province,China(No.201801D121267).
文摘In this paper,a novel compound was developed by mixing H_(3)PO_(4)-modified cauliflower leaves hydrochar(CLH)and coal gangue-based Na-X zeolite(ZL).An alkaline soil contaminated with cadmium(Cd)and lead(Pb)was amended through the individual and synergistic application of CLH and ZL(1%CLH,2%CLH,1%ZL,2%ZL and 1%CLH+1%ZL),and Chinese cabbage was grown on it.Individual application of CLH was superior to ZL on decreasing the pH of alkaline soil and increasing soil available phosphorus(Olsen-P)and soil organic matter(SOM).In contrast,their combined application significantly improved the soil cation exchange capacity(CEC).Besides,the 1%CLH+1%ZL was the most efficient treatment in decreasing diethylenetriamine pentaacetate(DTPA)-extractable Cd/Pb and concentrations of these two metals in cabbage root and shoot.Their synergistic application could better increase Cd and Pb immobilization and cabbage yield than their alone application.Furthermore,the immobilization of Pb for all treatments was higher than that of Cd.The synergistic immobilization mechanism of CLH and ZL reflected that the CLH precipitated and complexed with these two metals,which may block the pores of hydrochar or wrap on the surface of hydrochar.So the continuous adsorption and complexation were prevented.Nevertheless,ZL could probably alleviate this obstacle.This finding provides helpful information about using CLH combined with ZL as a soil stabilizer to immobilize heavy metals in contaminated alkaline soil.
基金supported by the Opening Project of Key Laboratory of Agricultural Renewable Resource Utilization Technology (No.HLJHDNY2104)Funding for the National Natural Science Foundation of China (NSFC U21A20162)+2 种基金Heilongjiang Postdoctoral Financial Assistance (LBH-Z21042)University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province (UNPYSCT-2020106)Sichuan Science and Technology Program (2022NSFSC1162).
文摘Hydrochar prepared with four typical biowastes,pine wood,food waste,digested sewage sludge,and Chlorella were applied for the promotion of anaerobic digestion.The gas production and substrate composition were analyzed associated with the hydrochar characteristics.The results suggested that Chlorella hydrochar(C-C)showed the highest cumulative yield of methane(approximately 345 mL)with high total organic carbon(TOC)removal efficiency and low volatile fatty acids(VAFs)concentration.Especially,food waste hydrochar(F-C)showed a poor effect on anaerobic digestion and aroused 1.4–1.6 g/L accumulation of VAFs,in which the toxic components may account for the low efficiency.The C-C and sludge hydrochar(S-C)may develop direct interspecific electron transport(DIET)to facilitate the generation of methane by both surface groups and conductivity of the body structure,unlike pinewood hydrochar(P-C),which mainly depended on the aromatic matrix structure of hydrochar body.This work suggested that C-C can be the best candidate for the facilitation of anaerobic digestion,and N-containing biowaste like algae and lignocellulose like pine wood may establish different DIET pathways based on the physicochemical characteristics of hydrochar.
基金supported by the Fundamental Research Funds for the Central Universities of Southwest Jiaotong University,supported by Sichuan Science and Technology Program(2021YFS0284).
文摘Hydrothermal carbonization is highly applicable to high moisture biomass upgrading due to the fact that moist-ure involved can be directly used as reaction media under the subcritical-water region.With this,value-added utilization of hydrochar as solid fuel with high carbon and energy density is one of the important pathways for biomass conversion.In this review,the dewatering properties of hydrochar after the hydrothermal carbonization of biowaste,coalification degree with elemental composition and evolution,pelletization of hydrochar to enhance the mechanical properties and density,coupled with the combustion properties of hydrochar biofuel were discussed with various biomass and carbonization parameters.Potential applications for the co-combustion with coal,cleaner properties and energy balance for biowaste hydrothermal carbonization were presented as well as the challenges.
基金financial support by the National Natural Science Foundation of China(No.41472095)the Open Fund of Key Laboratory of Exploration Technologies for Oil and Gas Resources(Yangtze University)+1 种基金Ministry of Education(No.K2018-05)the Foundation of Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals,Shandong University of Science and Technology(Grant No.DMSM2018041).
文摘The corncob hydrochar is prepared by using a stainless autoclave at 230?C for 8 h.The products are characterized by elemental analyzer,Fourier Transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and scanning electron microscope(SEM).The effects of hydrochar dosage,pH,adsorption time and phenol concentration on the adsorption performance of hydrochar are investigated by means of single-factor experimental analysis.Based on the experiments the adsorption thermodynamic and kinetics are tentatively discussed.The results show that abundant oxygen-containing functional groups are scattered on the surface of the corncob hydrochar.The adsorption kinetics of phenol on the hydrochar corresponds well with pseudo-second-order kinetic model.Thermodynamic studies indicate that Freundlich adsorption isotherm model is much better than Langmuir model in describing the adsorption of phenol on the corncob hydrochar at 25?C-45?C.This study provides scientific basis for the development of cheap and efficient adsorbents for the removal of phenols derived from oilfield wastewater.
基金The financial support from the National Natural Science Foundation of China(Grant No.52276202)the National Key R&D Program of China(Grant No.2020YFC1910100)+4 种基金the Tsinghua University-Shanxi Clean Energy Research Institute Innovation Project Seed FundHuaneng Group Science and Technology Research Project(Grant No.KTHT-U22YYJC12)the International Joint Mission On Climate Change and Carbon NeutralityTsinghua-Toyota Joint Research Fundand State Key Laboratory of Chemical Engineering(Grant No.SKL-ChE-22A03)are gratefully acknowledged.
文摘Lignin,an abundant aromatic polymer in nature,has received significant attention for its potential in the production of bio-oils and chemicals owing to increased resource availability and environmental issues.The hydrodeoxygenation of guaiacol,a lignin-derived monomer,can produce cyclohexanol,a nylon precursor,in a carbon-negative and environmentally friendly manner.This study explored the porous properties and the effects of activation methods on the Ru-based catalyst supported by environmentally friendly and cost-effective hydrochar.Highly selective cleavage of C_(ary)-O bonds was achieved under mild conditions(160°C,0.2 MPa H_(2),and 4 h),and alkali activation further improved the catalytic activity.Various characterization methods revealedthat hydrothermal treatment and alkali activation relatively contributed to the excellent performance of the catalysts and influenced their porous structure and Ru dispersion.X-ray photoelectron spectroscopy results revealed an increased formation of metallic ruthenium,indicating the effective regulation of interaction between active sites and supports.This synergistic approach used in this study,involving the valorization of cellulose-derived hydrochar and the selective production of nylon precursors from lignin-derived guaiacol,indicated the comprehensive and sustainable utilization of biomass resources.
基金financially by the Indonesian Endowment Fund for Education(LPDP)through“RISPRO KI”the International Research Collaboration(Grant No.RISPRO/KI/B1/KOM/12/11684/1/2020).
文摘This study investigates the simultaneous production of hydrochar and bioactive compounds from Ulva lactuca via a hydrothermal process.The experiment was carried out using a batch reaction vessel at different reaction temperatures of 180-220◦C and various holding times of 30-90 min.As expected,both temperature and time vigorously influenced hydrochar and bioactive compound production.The maximum hydrochar yield was at 32.4 wt%.The higher heating value(HHV)of hydrochar was observed in the range of 17.68-21.07 MJ kg^(-1),near the energy content of low-rank coals.The hydrochars exhibited contact angles higher than 90°(i.e.,94-108°)for a longer time,confirming their hydrophobic surfaces.The scanning electron microscope analysis(SEM)showed that the hydrothermal process enables cracks in the spherical shape of raw U.lactuca into small and porous particles.Besides producing hydrochar,the hydrothermal process of U.lactuca also gives promising antioxidants and phenolics as bioactive compounds.The highest total phenolic content and antioxidant activity could be achieved in hydrolysate at 200℃and 30 min with the value of 1.20±0.12 mg/g and 71.6±1.3%,respectively.
基金supported by the Shenzhen Fundamental Research Program(No.GXWD20201231165807007-20220724202837001).
文摘Hydrothermal treatment(HTT)can efficiently valorize the digestate after anaerobic digestion.However,the disposal of the HTT liquid is challenging.This paper proposes a method to recover energy through the anaerobic co-digestion of food waste and HTT liquid fraction.The effect of HTT liquid recirculation on anaerobic co-digestion performance was investigated.This study focused on the self-generated hydrochars that remained in the HTT supernatant after centrifugation.The effect of the self-generated hydrochars on the methane(CH_(4))yield and microbial communities were discussed.After adding HTT liquids treated at 140 and 180C,the maximum CH4 production increased to 309.36 and 331.61 mL per g COD,respectively.The HTT liquid exhibited a pH buffering effect and kept a favorable pH for the anaerobic co-digestion.In addition,the self-generated hydrochars with higher carbon content and large oxygen-containing functional groups remained in HTT liquid.They increased the electron transferring rate of the anaerobic co-digestion.The increased relative abundance of Methanosarcina,Syntrophomonadaceae,and Synergistota was observed with adding HTT liquid.The results of the principal component analysis indicate that the electron transferring rate constant had positive correlationships with the relative abundance of Methanosarcina,Syntrophomonadaceae,and Synergistota.This study can provide a good reference for the disposal of the HTT liquid and a novel insight regarding the mechanism for the anaerobic co-digestion.
基金This study was conducted under the auspices of the‘BIOCAS,circular BIOmass CAScade to 100%’project,which is funded by the European Union Interreg North Sea Region Project 38-2-4-17The funders played no role in the design of the study,the collection and analyses of data or the preparation of the manuscript.
文摘The hydrothermal carbonization(HTC)of biogas digestate alters the raw materials inherent characteristics to produce a carbon(C)-rich hydrochar(HC),with an improved suitability for soil amelioration.Numerous studies report conflicting impacts of various HC application rates on soil properties and plant growth.In this study,the influence of HC application rate on soil improvement and plant growth aspects was investigated in three diverse soils(Chernozem,Podzol,and Gleysol).Pot trials were conducted in which all soils were amended with 5,10,20 and 30%(w/w)HC in quintuplicate,with two controls of pure soil(with and without plants,respectively)also included.Prior to potting,soil samples were collected from all HC-amended soils and controls and analyzed for soil pH,plant available nutrients(PO4-P and K),and microbial activity using standard laboratory and statistical methods.Immediately after potting,a 6-week seed germination experiment using Chinese cabbage was conducted to determine germination success,followed by a plant growth experiment of equal duration and plant species to determine biomass success.At the end of the study(after a total plant growth period of 12 weeks),each pot was sampled and comparatively analyzed for the same soil properties as at the beginning of the study.Soil pH shifted toward the pH of the HC(6.6)in all soils over the course of the study,but was most expressed in the 20%and 30%application rates,confirming the well-documented liming effect of HC.The addition of HC increased the PO4-P and K contents,particularly with 20%and 30%HC amendments.These results are proposedly due to the large labile C fraction of the HC,which is easily degradable by microorganisms.The rapid decomposition of this C fraction prompted the quick release of the HCs inherently high PO4-P and K content into the soil,and in turn,further stimulated microbial activity,until this fraction was essentially depleted.HC addition did not inhibit seed germination at any rate,presumably due to a lack of phytotoxic compounds in the HC from aging and microbial processes,and furthermore,showed no significant impact(positive or negative)on plant growth in any soil,despite improved soil conditions.In conclusion,although less pronounced,soil improvements were still achievable and maintainable at lower application rates(5%and 10%),whereas higher rates did not ensure greater benefits for plant growth.While the addition of high rates of HC did not detrimentally effect soil quality or plant growth,it could lead to leaching if the nutrient supply exceeds plant requirements and the soil’s nutrient retention capacity.Therefore,this study validates the previous study in the effectiveness of the biogas digestate HC for soil amelioration and suggests that smaller regularly repeated HC applications may be recommendable for soil improvement.
基金National Natural Science Foundation of China(Nos.42107398,42277332 and 42207453)Natural Science Foundation of Jiangsu Province(BK20210358 and BK20221428)+2 种基金Ecological Environment Research Project of Jiangsu Province(Policy Guidance 2021006)China Postdoctoral Science Foundation(2020M68618)Y.F.Feng thanks the support of“333”High-level Talents Training Project of Jiangsu Province(2022-3-23-083).
文摘Hydrothermal carbonization(HTC)technology has increasingly been considered for biomass conversion applications because of its economic and environmental advantages.As an HTC conversion product,hydrochar has been widely used in the agricultural and environmental fields for decades.A CiteSpace-based system analysis was used for conducting a bibliometric study to understand the state of hydrochar environmental application research from 2011 to 2021.Researchers had a basic understanding of hydrochar between 2011 and 2016 when they discovered hydrochar could apply to agricultural and environmental improvement projects.Keyword clustering results of the literature published in 2017-2021 showed that soil quality and plant growth were the major research topics,followed by carbon capture and greenhouse gas emissions,organic pollutant removal,and heavy metal adsorption and its bioavailability.This review also pointed out the challenge and perspective for hydrochar research and application,namely:(1)the environmental effects of hydrochar on soils need to be clarified in terms of the scope and conditions;(2)the influence of soil microorganisms needs to be investigated to illustrate the impact of hydrochar on greenhouse gas emissions;(3)combined heavy metal and organic contaminant sorption experiments for hydrochar need to be conducted for large-scale applications;(4)more research needs to be conducted to reveal the economic benefits of hydrochar and the coupling of hydrochar with anaerobic digestion technology.This review suggested that it would be valuable to create a database that contains detailed information on how hydrochar got from different sources,and different preparation conditions can be applied in the environmental field.
基金financially supported by the State Grid Corporation Science and Technology Project(Grant No.5400-202031205A-0-0-00)Research and application of rural comprehensive energy recycling technology based on biomass-power-heat coupling and National Dairy Industry and Technology System(CARS-36).
文摘To realize the synergistic treatment of dairy cow manure solids and dairy cattle breeding sewage,this study produced phosphorus-modified hydrochar by dairy cow manure solids impregnated with potassium phosphate(K_(3)PO_(4)).And then,the adsorption characteristics of Cu(Ⅱ)and ammonium(NH_(4)^(+))in dairy cattle breeding sewage under different dosages and adsorption time conditions of modified hydrochar were explored.The results show that the specific surface area and total pore volume of the hydrochar were increased by phosphorus-modified.The adsorption amount of hydrochar per unit-mass decreased with the increase in the dosage.With the increase in the dosage,the adsorption capacity of Cu(Ⅱ)decreased from the initial 26.16 mg/g to 3.38 mg/g.The adsorption of Cu(Ⅱ)and NH_(4)^(+)in sewage by hydrochar was mainly chemical adsorption,which was mainly affected by chelation and ion exchange.This adsorption was more inclined to single-molecular layer adsorption.Both the pH values and the ionic strength influenced the competitive adsorption between Cu(Ⅱ)and NH_(4)^(+).The higher the pH value was,the greater the adsorption amount,and the stronger the adsorption capacity by hydrochar.Moreover,the increase in the ionic strength decreases the adsorption capacity of hydrochar.
基金the National Natural Science Foundation of China(Nos.41877090 and 42107398)Natural Science Foundation of Jiangsu Province(BK20181165 and BK20210358)+1 种基金China Postdoctoral Science Foundation(2020M68618)Yunnan Branch of China National Tobacco Corporation(2022530000241022).
文摘Hydrochar has potential applications in soil improvement and heavy metal remediation.Hydrochar would undergo the process of aging when introduced into the soil,altering its properties.However,recent studies have focused mainly on the artificial aging of hydrochar,which could not reveal the cumulative effect of multiple environmental factors.Therefore,the periodical monitoring of the property and sorption behavior of hydrochar after amending soils is necessary to better understand the multifaceted mechanisms associated with the natural aging of hydrochar.This study selected the sludge-derived hydrochar(SLHC)as a typical hydrochar and applied a 16-month rice-wheat-rice rotation to mimic the natural aging of hydrochar,focusing on changing properties and cadmium(Cd)sorption and literature contrast between aging strategies and biochar types.The porosity,O abundance,and ash content of 16-month aged SLHC increased by 37%,47%,and 8.5%,respectively,facilitating Cd sorption due to surface complexation,pore sorption,and precipitation.The sorption percentage of Cd to SLHC was in the range of 11-14%for SLHC-A0 and increased to 17-31%for SLHC-A4 and 20-32%for SLHC-A16 after natural aging.The natural aging of SLHC induced by ash content played an essential role in Cd sorption site heterogeneity.Linear regression analysis showed that aging strategies on sorption behavior significantly differed between biochars.Thus,studies involving natural aging with multiple environmental factors are preferred over those involving chemical or biological aging.Future studies should continue to explore the mechanisms of natural aging-induced heavy metal sorption between hydrochar and pyrochar.These results improve insights to appraise the potential of SLHC as soil amendments to alleviate the adverse effects of heavy metal contamination and provide an essential basis for researchers and staff in soil management and environmental prevention.
文摘Hydrochar(HC)produced by the hydrothermal carbonization(HTC)of typically wet biomass is generally considered to be less effective for carbon(C)sequestration in soils compared to biochar(BC)by pyrolysis,due to a higher content of more easily decomposable C.Although the recalcitrance of HC is suggested to improve with increasing HTC production temperature,the way it interacts and becomes associated with soil organic matter(SOM)fractions of different stabilities against decomposition,may also influence its effectiveness for C sequestration in soils.In that respect,this study aimed to verify the potential of HCs from maize silage produced at different HTC temperatures(190,210 and 230℃)for C sequestration in a HC-amended sandy loam Podzol.To do this,we conducted a pot trial experiment and traced the fate of HC-derived C(HC-C)within different SOM fractions,namely the free-and occluded particulate organic matter(POMF and POMO,respectively)fractions and that comprising organic matter(OM)bound to clays(OMCl).Approx.1 year after applying 5%of the different HTC temperature HCs to the soil,the SOM fractions were isolated by density fractionation for each HC treatment(HC190,HC210 and HC230)and the control(absent of HC).All fractions and the HCs were analyzed for organic C(OC)content and isotopic signatures(δ^(13)C).From the δ^(13)C signatures,the amount of HC-C and native soil organic carbon(SOC)within each fraction was calculated.Increased C contents and decreased H/C and O/C ratios were observed with increasing HTC production temperatures,which sug-gests a lower stability for the low temperature HC.After ca.1 year,a loss of~20-23%of the bulk soil TOC was found in the HC-amended soils.The POMF fraction of the HC-amended soils showed losses of 68-81%HC-C and 52-72%native SOC,which may be due to a positive priming effect caused by HC addition.The POM_(O) and OM_(Cl) fractions of the HC-amended soils contained more OC than the control,indicating the integration of HC-C together with SOM within these more stable fractions,while the effect of HTC production temperature on the level of decomposition of the resultant HCs was negligible.In all HC treatments,the OM_(Cl) fraction comprised the least amount of HC-C,thus showing the weakest response to C amendment.In conclusion,long(er)-term research on the C net balance that accounts for the observed priming-induced TOC losses and the HC-C enrichment in more stable fractions is required to verify the potential of the different HCs for the purpose of C sequestration in soils.
基金This work was funded by the National Undergraduate Training Program for Innovation and Entrepreneurship(No.202010288024Z)National Natural Science Foundation of China(No.42107398)+1 种基金Natural Science Foundation of Jiangsu Province(BK20210358)China Postdoctoral Science Foundation(2020M68618).
文摘The cellulose-based hydrogel has been widely applied for soil water retention and nutrient re-lease agents for several decades.Embedding the inorganic materials into hydrogels is an excellent strategy to improve the inherent limits of the cellulose-based hydrogel.Notably,municipal sludge-derived hydrochar(HC)has reduced the environmental burden and offered a potential hydrogel carrier to control water-retention and nutrient-release.However,the above function for plant growth of hydrochar-embedded carboxymethyl cellulose-g-poly(acrylic acid)(CMC-g-PAA/HC)is unknown,and relevant reports are lacking.This study investigated the water retention,nutri-ent release behavior,and effect of germination and plant growth of CMC-g-PAA/HC hydrogel.Characterization results showed that HC was successfully incorporated into CMC-g-PAA/HC with 6.0%higher thermostability,7.2-21.0%lower swelling ratio(SR)in water,and substantial SR in phosphate solution(P-solution).The water loss rate of CMC-g-PAA/HC in P-solution or wa-ter owned a more significant temperature response(7.9-15.0 folds)than CMC-g-PAA(8.2-10.0 folds).Moreover,4.0%higher n value and more 18.5%released P for CMC-g-PAA/HC were also observed.These phenomena were due to restricting the polymer chains movement and the wa-ter molecules diffusion inside the hydrogels with HC.Phytotoxicity assessments showed that HC in CMC-g-PAA/HC could effectively alleviate the inhibition effects on rape germination retained with 78.3%germination vigor and 80.0%germination ratio,even dramatically improved plant growth to 28 d.The results of this study demonstrated a new route for developing eco-friendly CMC-g-PAA/HC hydrogel,advantageous as a water retention agent and nutrient carrier in arid and semiarid regions.
基金Open Access funding provided by Projekt DEAL.This study was conducted under the auspices of the Circular BIOmass CAScade to 100%(BIOCAS)project,which is funded by the European Union Interreg North Sea Region Project 38-2-4-17.
文摘Hydrochar(HC),produced by hydrothermal carbonization,offers technical advantages over biochar(BC)produced by pyrolysis,and is suitable for soil amelioration,carbon sequestration,and enhanced plant growth.BC grain size has been shown to influence nutrient retention,microbial colonization and aggregate formation;however,similar research for HC is lacking.Pot trials were conducted to investigate the influence of HC grain size[coarse(6.3-2 mm),medium(2-0.63 mm)and fine(<0.63 mm)],produced from biogas digestate,for soil improvement in three soils:loamy Chernozem,sandy Podzol,and clayey Gleysol,at a 5%HC application rate(w/w).All soils including two controls(with and without plants)were analysed for water holding capacity(WHC),cation exchange capacity(CEC),wet aggregate stability,pH,plant available nutrients(PO_(4)-P,K and N_(min))and germination and biomass success using standard laboratory and statistical methods.Soil pH showed a compensatory shift toward the HC pH(7.2)in all soils over the course of the study.For example,the pH of the medium grained HC treatment for the Chernozem decreased from 7.9 to 7.2 and increased in the Podzol and Gleysol from 5.9 to 6.1 and 4.9 to 5.5,respectively.The nutrient-rich HC(2034±38.3 mg kg^(−1) PO_(4)-P and 2612.5±268.7 mg kg^(−1) K content)provided only a short-term supply of nutrients,due to the relatively easily mineralized fraction of HC,which allowed for quick nutrient release.The pH and PO_(4)-P effects were most pronounced in the fine grained HC treatments,with a~87%,~308%and~2500%increase in PO_(4)-P content in the Chernozem,Podzol and Gleysol,respectively,compared to the controls at the beginning of the study.The same trend was observed for the K and NH_(4)^(+)content in the fine and medium grained HC treatments in all soils.No seed germination inhibition of Chinese cabbage was observed,with average germina-tion rates>50%in all soils.An effect on NO_(3)^(−)content was indeterminable,while there was little to no effect on biomass production,WHC,CEC and aggregate stability.In conclusion,the application of 5%fine grained HC significantly influenced the nutrient content over a short-term.However,the application rate was insufficient to substantially improve plant growth,nor to sustain a longer-term nutrients supply,regardless of grain size.
