The uncontrolled discharge of industrial wastewater leads to a significant cadmium(Cd)accumulation in waste activated sludge(WAS),posing a serious threat to the steady operation of the anaerobic digestion(AD)system in...The uncontrolled discharge of industrial wastewater leads to a significant cadmium(Cd)accumulation in waste activated sludge(WAS),posing a serious threat to the steady operation of the anaerobic digestion(AD)system in wastewater treatment plants(WWTPs).Therefore,developing a viable approach to cope with the adverse effects of high-concentration Cd on the AD system is urgently required.This study aims to investigate the potential of using anionic polyacrylamide(APAM),a commonly used agent in WWTPs,to mitigate the adverse effects of Cd in a toxic amount(i.e.,5.0 mg per g total suspended solids(TSS))on AD of WAS.The results showed that the effectiveness of higher APAM on Cd toxicity alleviation was less than that of lower APAM at the studied level(i.e.,the effectiveness order was 1.5 mg APAM per g TSS>3.0 mg APAM per g TSS>6.0 mg APAM per g TSS).The moderate supplement of APAM(i.e.,1.5 mg per g TSS)recovered the accumulative methane yield from 190.5±3.6 to 228.9±4.1 mL per g volatile solids by promoting solubilization,hydrolysis,and acidification processes related to methane production.The application of APAM also increased the abundance of key microbes in the AD system,especially Methanolinea among methanogens and Caldilineaceae among hydrolyzers.Furthermore,APAM facilitated the key enzyme activities involved in AD processes and reduced reactive oxygen species(induced by Cd)production via adsorption/enmeshment of Cd by APAM.These findings demonstrate the feasibility of using moderate APAM to mitigate Cd toxicity during AD,providing a promising solution for controlling Cd or other heavy metal toxicity in WWTPs.展开更多
The polyacrylamide which is directly added into concrete shows strong water absorption property.Thus the construction of underwater constructure would demand high amount of water,resulting in poor workability of concr...The polyacrylamide which is directly added into concrete shows strong water absorption property.Thus the construction of underwater constructure would demand high amount of water,resulting in poor workability of concrete and strength shrinkage after hardening.Herein,a kind of anionic polyacrylamide(APAM)grafted with water reducing functional group(-COOH)was synthesized at low temperatures by partial factor design and response surface design.The structure and morphology of APAM were characterized by UV,FTIR and SEM methods.The experimental results show that the molecular weight of the synthesized APAM could reach 11 million,under the condition that the temperature was 35℃,the pH value was 8,the monomer concentration was 27wt%,the initiator dosage was 0.6wt%,and the monomer ratio(n(AM):n(AA))was 3.When the APAM was applied into the underwater slurry,it presented good flocculation and low water demand.When the dosage was 1%of the mass of the cement,the water demand increased by 12%,which could meet the self-leveling and anti-dispersity of the underwater slurry at the same time.This technology provides technical guidance for the large-scale industrial production of polyacrylamide for underwater concrete construction while achieving environmental protection during production.展开更多
Selective flocculation is a new method to solve the problem of China's bauxite de-silication besides flotation and reverse flotation. The method of selective flocculation of bauxite using hydrolyzed polyacrylamide...Selective flocculation is a new method to solve the problem of China's bauxite de-silication besides flotation and reverse flotation. The method of selective flocculation of bauxite using hydrolyzed polyacrylamide as flocculant was experimented and evaluated. The results of diaspore and kaolinite single mineral settling tests show that the difference between settlement yield of kaolinite(settling 15 min) and diaspore(settling 3 min) increases from 16% to 60% by adding flocculant at pH=7. Results of selective flocculation experiment of bauxite show that the higher concentrate grade(65.75) and Al-Si ratio(7.34) could be obtained with sodium carbonate as dispersant compared with sodium hexametaphosphate; under the action of flocculating agent, the concentrate grade and Al-Si ratio increase to 67.99 and 9.01. These results could meet the requirements of Bayer production, and the simpler process was expected to cost far less than traditional flotation method and a promising de-silication method of bauxite.展开更多
Interaction of polymer-containing injected fluids with shale is a widely studied phenomenon, but much is still unknown about the interaction of charged polyacrylamides such as anionic and cationic polyacrylamides with...Interaction of polymer-containing injected fluids with shale is a widely studied phenomenon, but much is still unknown about the interaction of charged polyacrylamides such as anionic and cationic polyacrylamides with shale. The nature of interaction of charged polyacrylamides with shale is not well understood, especially from the perspective of assessing the potential for polyacrylamides to cause formation damage. Zeta potential and rheological measurements were made for Chattanooga and Pride Mountain shales suspended in polyacrylamide solutions with and without inorganic salts and tetramethyl ammonium chloride（TMAC）. The change in zeta potential and viscosity with time was recorded. The magnitude of decrease in the absolute value of zeta potential with time is indicative of adsorption of polymer on the surface of shale and serves as a measure of the extent of polymer interaction with shale. The salts that were used in this study are potassium chloride（KCl）, sodium chloride（Na Cl）. This study quantified the interaction of anionic and cationic polyacrylamide with different North American shales.From the experimental results, it was determined that the polyacrylamides can interact strongly with shale, particularly the cationic polyacrylamide. The objective of this study was to determine the extent of interaction of anionic and cationic polyacrylamide with each shale sample in the presence of additives such as salts.展开更多
Si anode is of paramount importance for advanced energy-dense lithium-ion batteries(LIBs).However,the large volume change as well as stress generates during its lithiation-delithiation process poses a great challenge ...Si anode is of paramount importance for advanced energy-dense lithium-ion batteries(LIBs).However,the large volume change as well as stress generates during its lithiation-delithiation process poses a great challenge to the long-term cycling and hindering its application.Herein this work,a composite binder is prepared with a soft component,guar gum(GG),and a rigid linear polymer,anionic polyacrylamide(APAM).Rich hydroxy,carboxyl,and amide groups on the polymer chains not only enable intermolecular crosslinking to form a web-like binder,A2G1,but also realize strong chemical binding as well as physical encapsulating to Si particles.The resultant electrode shows limited thickness change of merely 9%on lithiation and almost recovers its original thickness on delithiation.It demonstrates high reversible capacity of 2104.3 mAh g^(-1)after 100 cycles at a current density of 1800 mA g^(-1),and in constant capacity(1000 mAh g^(-1))test,it also shows a long life of 392 cycles.Therefore,this soft-hard combining web-like binder illustrates its great potential in the future applications.展开更多
基金supported by the project of the National Natural Science Foundation of China(NSFC):52070075the Natural Science Foundation of Hunan Province:2020JJ4187.
文摘The uncontrolled discharge of industrial wastewater leads to a significant cadmium(Cd)accumulation in waste activated sludge(WAS),posing a serious threat to the steady operation of the anaerobic digestion(AD)system in wastewater treatment plants(WWTPs).Therefore,developing a viable approach to cope with the adverse effects of high-concentration Cd on the AD system is urgently required.This study aims to investigate the potential of using anionic polyacrylamide(APAM),a commonly used agent in WWTPs,to mitigate the adverse effects of Cd in a toxic amount(i.e.,5.0 mg per g total suspended solids(TSS))on AD of WAS.The results showed that the effectiveness of higher APAM on Cd toxicity alleviation was less than that of lower APAM at the studied level(i.e.,the effectiveness order was 1.5 mg APAM per g TSS>3.0 mg APAM per g TSS>6.0 mg APAM per g TSS).The moderate supplement of APAM(i.e.,1.5 mg per g TSS)recovered the accumulative methane yield from 190.5±3.6 to 228.9±4.1 mL per g volatile solids by promoting solubilization,hydrolysis,and acidification processes related to methane production.The application of APAM also increased the abundance of key microbes in the AD system,especially Methanolinea among methanogens and Caldilineaceae among hydrolyzers.Furthermore,APAM facilitated the key enzyme activities involved in AD processes and reduced reactive oxygen species(induced by Cd)production via adsorption/enmeshment of Cd by APAM.These findings demonstrate the feasibility of using moderate APAM to mitigate Cd toxicity during AD,providing a promising solution for controlling Cd or other heavy metal toxicity in WWTPs.
基金Funded by the National Natural Science Foundation of China(No.51778378)the Natural Science Foundation of Hebei Province(No.E2022210103)。
文摘The polyacrylamide which is directly added into concrete shows strong water absorption property.Thus the construction of underwater constructure would demand high amount of water,resulting in poor workability of concrete and strength shrinkage after hardening.Herein,a kind of anionic polyacrylamide(APAM)grafted with water reducing functional group(-COOH)was synthesized at low temperatures by partial factor design and response surface design.The structure and morphology of APAM were characterized by UV,FTIR and SEM methods.The experimental results show that the molecular weight of the synthesized APAM could reach 11 million,under the condition that the temperature was 35℃,the pH value was 8,the monomer concentration was 27wt%,the initiator dosage was 0.6wt%,and the monomer ratio(n(AM):n(AA))was 3.When the APAM was applied into the underwater slurry,it presented good flocculation and low water demand.When the dosage was 1%of the mass of the cement,the water demand increased by 12%,which could meet the self-leveling and anti-dispersity of the underwater slurry at the same time.This technology provides technical guidance for the large-scale industrial production of polyacrylamide for underwater concrete construction while achieving environmental protection during production.
基金Project(2005CB623701)supported by the National Key Basic Research Program(973)of China
文摘Selective flocculation is a new method to solve the problem of China's bauxite de-silication besides flotation and reverse flotation. The method of selective flocculation of bauxite using hydrolyzed polyacrylamide as flocculant was experimented and evaluated. The results of diaspore and kaolinite single mineral settling tests show that the difference between settlement yield of kaolinite(settling 15 min) and diaspore(settling 3 min) increases from 16% to 60% by adding flocculant at pH=7. Results of selective flocculation experiment of bauxite show that the higher concentrate grade(65.75) and Al-Si ratio(7.34) could be obtained with sodium carbonate as dispersant compared with sodium hexametaphosphate; under the action of flocculating agent, the concentrate grade and Al-Si ratio increase to 67.99 and 9.01. These results could meet the requirements of Bayer production, and the simpler process was expected to cost far less than traditional flotation method and a promising de-silication method of bauxite.
文摘Interaction of polymer-containing injected fluids with shale is a widely studied phenomenon, but much is still unknown about the interaction of charged polyacrylamides such as anionic and cationic polyacrylamides with shale. The nature of interaction of charged polyacrylamides with shale is not well understood, especially from the perspective of assessing the potential for polyacrylamides to cause formation damage. Zeta potential and rheological measurements were made for Chattanooga and Pride Mountain shales suspended in polyacrylamide solutions with and without inorganic salts and tetramethyl ammonium chloride（TMAC）. The change in zeta potential and viscosity with time was recorded. The magnitude of decrease in the absolute value of zeta potential with time is indicative of adsorption of polymer on the surface of shale and serves as a measure of the extent of polymer interaction with shale. The salts that were used in this study are potassium chloride（KCl）, sodium chloride（Na Cl）. This study quantified the interaction of anionic and cationic polyacrylamide with different North American shales.From the experimental results, it was determined that the polyacrylamides can interact strongly with shale, particularly the cationic polyacrylamide. The objective of this study was to determine the extent of interaction of anionic and cationic polyacrylamide with each shale sample in the presence of additives such as salts.
基金supported by the National Key Research and Development Program of China(No.2021YFB2500100)Science Fund for Creative Research Groupsof the National Natural Science Foundation of China(No.21921005)+1 种基金Beijing Natural Science Foundation(No.2222031)Hebei Natural Science Foundation(No.B2020103028)
文摘Si anode is of paramount importance for advanced energy-dense lithium-ion batteries(LIBs).However,the large volume change as well as stress generates during its lithiation-delithiation process poses a great challenge to the long-term cycling and hindering its application.Herein this work,a composite binder is prepared with a soft component,guar gum(GG),and a rigid linear polymer,anionic polyacrylamide(APAM).Rich hydroxy,carboxyl,and amide groups on the polymer chains not only enable intermolecular crosslinking to form a web-like binder,A2G1,but also realize strong chemical binding as well as physical encapsulating to Si particles.The resultant electrode shows limited thickness change of merely 9%on lithiation and almost recovers its original thickness on delithiation.It demonstrates high reversible capacity of 2104.3 mAh g^(-1)after 100 cycles at a current density of 1800 mA g^(-1),and in constant capacity(1000 mAh g^(-1))test,it also shows a long life of 392 cycles.Therefore,this soft-hard combining web-like binder illustrates its great potential in the future applications.
