Adsorption behavior of bisphenol A on bentonite-loess mixtures

The leakage of chemical compounds in landfill leachate led to serious environment pollution, especially, the compounds termed endocrine disruptors such as bisphenol A (BPA). It is very important to study the adsorption behavior of endocrine disruptors in modified soil for predicting and evaluating the potential harm of endocrine disruptors to the soil. Bentonite-amended Chinese loess mixtures, with various proportions of bentonite, were used for the removal of BPA from an aqueous solution. A batch test was used to investigate the adsorption properties of bisphenol A on bentonite and Chinese loess mixtures. The influences of bentonite proportion, temperature, reaction time, pH, and soil-water ratios on the adsorption process were considered. The Fourier transform infrared spectra (FTIR) was used to clarify the change of functional groups before and after the adsorption of BPA on soil. The adsorption mechanism of BPA on soil was discussed preliminary. The results show that the addition of bentonite to the loess can improve the adsorption rate of BPA. The adsorption of BPA was mainly a spontaneous, exothermic, entropy decreasing physical adsorption process. The interaction between bentonite content and reaction concentration had a beneficial effect on BPA adsorption. The linear relationship between bentonite content and adsorption capacity was obtained. The results indicate that bentonite amended loess can provide a good liner for BPA.