BS/DTAB复配修饰膨润土的表征及对苯酚、菲的不同吸附模式

为了探究总修饰比例对复配修饰膨润土表面结构特性及对不同疏水性的有机污染物(苯酚、菲)吸附模式的影响。采用十二烷基三甲基溴化铵(DTAB)复配十二烷基二甲基甜菜碱(BS-12)修饰膨润土,研究了复配修饰膨润土总碳和总氮含量、比表面(SBET)、X射线衍射(XRD)、红外光谱(FTIR)和扫描电镜(SEM)的特征,并分析了总修饰比例、表面特性及吸附量三者相关性。结果显示:红外图谱及电镜扫描均证实了DTAB在BS-12两性膨润土表面的修饰;随着总修饰比例的增大,复配修饰膨润土对苯酚及菲的吸附量增大,在总修饰比例超出150%CEC后吸附量开始下降;总碳含量、层间距(d001)变化规律与总修饰比例成正比,比表面积变化规律与总修饰比例成反比,且变化幅度均在总修饰比例超出150%CEC后增大。相关性分析结果表明,复配修饰膨润土对苯酚和菲的吸附能力由总碳含量决定,BS/DTAB复配修饰膨润土对苯酚吸附模式为分配吸附,而对菲的吸附模式为分配吸附和表面吸附共存的模式。

Characterization of different adsorption mechanisms of phenol and phenanthrene with BS/DTAB modified bentonite

This paper investigates the association between the combined modified ratio, surface characteristics, and adsorption of organic pollutants on modified bentonite, modified by amphoteric modifier, dodecyl dimethyl betaine(BS-12), and cationic modifier, Dodecyltrimethylammonium Bromide(DTAB). Total carbon content, specific surface area(S_BET), X-ray diffraction(XRD), infrared spectroscopy(FTIR)and scanning electron microscopy(SEM)were studied to determine the determinants of phenol and phenanthrene adsorption on BS/DTAB combined modified bentonites. Results showed that the DTAB on the surface of BS-12 amphoteric bentonite was confirmed by the FTIR and SEM. With the increase of the total modification ratio(TMR), adsorption of phenol and phenanthrene increased, and the adsorption began to decrease after the TMR exceeded 150% CEC. Change of the total carbon content and layer spacing(d₀₀₁)of combined modified bentonites were proportional to the TMR, the change of S_BET was inversely proportional to the TMR, and the variation range is increased after the TMR exceeded 150% CEC. Results of correlation analysis showed that the adsorption of phenol and phenanthrene to the bentonite was determined by the total carbon content, the sorption of phenol on the bentonite were of the mode of partitioning, while the sorption of phenanthrene of the mode of partitioning and surface adsorption.