摘要
为强化海泡石(Sep)对溶液中Cd2+的吸附性能,采用酸碱复合改性处理获得改性海泡石(ABsep),借助氮气吸脱附等温线、SEM-EDS、TEM、FTIR和XRD等技术分析了改性前后海泡石的结构特征,采用静态吸附实验研究了时间、ABsep/Cd2+质量比、温度、吸附剂用量、pH及共存离子等因素对ABsep吸附Cd2+的影响.结果表明,ABsep孔隙结构发达,比表面积、平均孔径和孔容分别较改性前增加66.1%、15.7%和34.8%,可交换性离子含量有所增加,主要成分为SiO2和Mg(OH)2.改性前后海泡石对Cd2+吸附过程能较好地以准二级动力学方程和Langmuir模型进行拟合,且均为自发吸热反应,以化学吸附为主并伴有物理性吸附;最佳ABsep/Cd2+质量比为3:1;298 K时Sips拟合ABsep对Cd2+最大饱和吸附量为142.43 mg·g-1,为改性前海泡石的3.55倍;随着吸附剂投加量的增加,Cd2+吸附量表现为先增大后减小,最佳用量为0.3 g·L-1;ABsep对Cd2+的吸附量随溶液初始pH的升高而增加最佳pH为7;不同浓度K+、Na+、Mg2+和Ca2+的存在均会对Cd2+的吸附产生一定的抑制作用其中Mg2+的抑制作用最强.
To enhance the adsorption capacity of sepiolite(Sep) on Cd2+ in solution,an acid-base Sep(ABsep) was obtained using the method of combined acid-base modification.The structural properties of Sep and ABsep were analyzed by adsorption-desorption isotherms of N2,scanning electron microscopy with energy dispersive X-ray spectroscopy(SEM-EDS),transmission electron microscopy(TEM),Fourier-transform infrared spectroscopy(FTIR),and X-ray powder diffraction(XRD).Static adsorption experiments were carried out to evaluate the effects of time,mass ratio of ABsep/Cd2+,temperature,adsorbent dose,pH,and coexisting ions on the adsorption of Cd2+by ABsep.The results showed that the pore structure of the ABsep was more developed than that of Sep.In comparison to Sep,the specific surface area,average pore diameter,and pore volume of ABsep increased by 66.1%,15.7%,and 34.8%,respectively,and the exchangeable ion contents also increased.The main components of the ABsep were SiO2 and Mg(OH)2.The adsorption process of Cd2+by Sep and ABsep could be well fitted with a pseudo-second-order kinetic equation and Langmuir isotherm,and both were spontaneous endothermic reactions,which were mainly chemical adsorption along with physical adsorption.The best mass ratio of ABsep:Cd2+ was 3:1,and the maximum saturated adsorption capacity fitted by the Sips model of the ABsep on Cd2+ at 298 K was 142.43 mg·g-1,which was 3.55 times that of Sep.As the adsorbent dose increased,the adsorption amounts of Cd2+ first increased and then decreased,with the optimum dose being 0.3 g·L-1.The amount of Cd2+ adsorption by the ABsep increased with the initial pH of the solution,whereby the best pH was 7.We also found that the presence of K+,Na+,Mg2+,and Ca2+ at different concentrations could inhibit the adsorption of Cd2+,whereby the inhibition of Mg2+ was the highest.
作者
谢厦
徐应明
闫翠侠
罗文文
孙约兵
XIE Sha;XU Ying-ming;YAN Cui-xia;LUO Wen-wen;SUN Yue-bing(Key Laboratory of Original Agro-Environmental Pollution Prevention and Control,Ministry of Agriculture and Rural Affairs,Agro-Environmental Protection Institute,Ministry of Agriculture and Rural Affairs,Tianjin 300191,China;Tianjin Key Laboratory of Agro-Environment and Agro-Product Safety,Agro-Environmental Protection Institute,Ministry of Agriculture and Rural Affairs,Tianjin 300191,China;College of Grassland and Environment Sciences,Xinjiang Agricultural University,Urumqi 830052,China)
出处
《环境科学》
EI
CAS
CSCD
北大核心
2020年第1期293-303,共11页
Environmental Science
基金
国家重点研发计划项目(2017YFD0801402,2018YFD080300)
天津市自然科学基金重点项目(17JCZDJC34200,18JCZDJC34000)
关键词
海泡石
酸碱改性
镉
亚结构特征
吸附
sepiolite
acidic and basic modification
cadmium
substructure
adsorption
