BS-12+DTAB复配修饰膨润土吸附Cr(Ⅵ)和Cd<sup>2+</sup>的研究

谢婷; 李文斌; 孟昭福; 路浩源; 任爽; YEK Sambath

文章摘要

谢婷,李文斌,孟昭福,路浩源,任爽,YEK Sambath.BS-12+DTAB复配修饰膨润土吸附Cr(Ⅵ)和Cd²⁺的研究[J].农业环境科学学报,2017,36(9):1778-1786.

BS-12+DTAB复配修饰膨润土吸附Cr(Ⅵ)和Cd²⁺的研究

Studies on Cr(Ⅵ) and Cd²⁺ adsorption onto bentonite modified by a BS-12+DTAB complex

投稿时间：2017-03-06

DOI：10.11654/jaes.2017-0279

中文关键词: 膨润土复配修饰吸附 Cr(Ⅵ) Cd²⁺

英文关键词: bentonite complex modification adsorption Cr(Ⅵ) Cd²⁺

基金项目:国家自然科学基金项目（41271244）；陕西省重点研发计划项目（2017SF-385）

作者	单位	E-mail
谢婷	西北农林科技大学资源环境学院, 陕西杨凌 712100
李文斌	西华师范大学环境科学与工程学院, 四川南充 637009
孟昭福	西北农林科技大学资源环境学院, 陕西杨凌 712100 农业部西北植物营养与农业环境重点实验室, 陕西杨凌 712100	zfmeng1996@263.net
路浩源	西北农林科技大学资源环境学院, 陕西杨凌 712100
任爽	西北农林科技大学资源环境学院, 陕西杨凌 712100
YEK Sambath	西北农林科技大学资源环境学院, 陕西杨凌 712100

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中文摘要:

为了探究和比较两性+阳离子复配修饰膨润土对不同类型重金属离子[Cr（Ⅵ）和Cd²⁺]的吸附效应及影响机制，采用阳离子型表面修饰剂十二烷基三甲基溴化铵（DTAB或DT）复配修饰两性表面修饰剂十二烷基二甲基甜菜碱（BS-12或BS）修饰膨润土，批处理法研究各复配修饰土样对Cr（Ⅵ）和Cd²⁺的等温吸附的异同，并对比温度、pH值和离子强度对吸附的影响。结果表明：各复配修饰膨润土对Cr（Ⅵ）和Cd²⁺的吸附等温线均符合Langmuir模型。供试土样对Cr（Ⅵ）的平衡吸附量呈现BS+150DT（150% CEC的DTAB复配修饰膨润土）> BS+100DT > BS+50DT > BS+25DT > BS > CK（膨润土）的趋势，且最大吸附量（q_m）为205.67 mmol·kg^-1（BS+150DT）。土样对Cd²⁺的平衡吸附量表现为BS > CK > BS+25DT > BS+50DT > BS+100DT > BS+150DT，其q_m值为232.38 mmol·kg^-1（100BS）。10~40℃范围内，CK、BS修饰土对Cr（Ⅵ）吸附量为增温正效应，而BS+DT复配修饰土对Cr（Ⅵ）吸附呈现自发、焓减和熵增的特征；各供试土样对Cd²⁺的吸附均表现为自发、焓增和熵增的特征。随着pH值的升高，各修饰土样对Cr（Ⅵ）的吸附量均逐渐降低，而对Cd²⁺的吸附量逐渐增加。离子强度增加不利于供试土样对Cr（Ⅵ）和Cd²⁺的吸附。BS+DT复配修饰膨润土表面的电荷类型、电荷数量是决定Cr（Ⅵ）和Cd²⁺吸附差异的主要因素。

英文摘要:

In order to compare the discrepancies between Cr(Ⅵ) and Cd²⁺ adsorption on bentonite modified by a mixture of amphoteric modifier, dodecyldimethyl betaine(BS-12), and cationic modifier, Dodecyltrimethyl ammonium Bromide(DTAB), batch method was used to study the influence of temperature, ionic strength, pH on discrepancies of adsorption of Cr(Ⅵ) and Cd²⁺ on different modified bentonites, and the thermodynamic properties were studied also. The results showed that:The Langmuir model was suited for adsorption isotherms of Cr(Ⅵ) and Cd²⁺ on different samples. The equilibrium adsorption capacity of Cr(Ⅵ) was ordered by BS+150DT(BS-12+150% CEC DTAB)> BS+100DT > BS+50DT > BS+25DT > BS > CK(unmodified bentonite) and BS+150DT treatment had the maximum adsorption capacity(q_m) 205.67 mmol·kg^-1. On the contrary, the sequence of equilibrium adsorption capacity of Cd²⁺ was BS > CK > BS+25DT > BS+50DT > BS+100DT > BS+150DT, and 100BS(100% CEC BS-12) had maximum Cd²⁺ adsorption 232.38 mmol·kg^-1. In the range of 10℃ to 40℃, the adsorption capacity of Cr(Ⅵ) on CK and BS modified bentonites were increased with increased temperature, while Cr(Ⅵ) adsorption on BS-DT bentonites was a spontaneous process with a decrease in enthalpy and an increase in entropy. The Cd²⁺ adsorption on different samples was a spontaneous process with an increase in enthalpy and an increase in entropy. With an increase of pH, the adsorption capacity of Cr(Ⅵ) decreased gradually, while the adsorption capacity of Cd²⁺ increased gradually. High ionic strength was not conducive to adsorption of Cr(Ⅵ) and Cd²⁺. Charge type of BS-DT complex modified bentonite was the crucial factor to difference between Cr(Ⅵ) and Cd²⁺ adsorption.

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