CTMAB-Modified Bentonite–Based PRB in Remediating Cr(VI) Contaminated Groundwater

Cetyl trimethylammonium bromide (CTMAB)–modified bentonite was synthesized as adsorbent for the removal of Cr(VI) from aqueous solutions. Batch adsorption studies show that the adsorption capacity of CTMAB-modified bentonite (1.962 mg g −1 ) was about 19 times higher than that of natural bentonite (0.101 mg g −1 ). The weakly acidic or neutral environment can improve the adsorption ability of both natural and modified bentonites. Cr(VI) adsorption onto CTMAB-modified bentonite follows the Langmuir model and obeys the pseudo-second-order model. In a fixed-bed column test, the adsorption capacities of 5% modified bentonite with 95% sand, and 10% modified bentonite with 90% sand were 0.31 mg g −1 and 0.35 mg g −1 , respectively. These values were much lower than their theoretical maximum adsorption capacity using the Langmuir model.