Firstly, the raw bentonite was converted to sodium bentonite, following the method described by Yu et al. [35]. The CTMAB-Bent was prepared by adding 10 g of sodium bentonite to CTMAB solution in amounts equivalent to the CEC of sodium bentonite (0.882 mmol/g),and stirring for 24 h at room temperature. The suspensions were then separated by centrifuge, washed with deionized water several times until no Br− was detected in the supernatant. The results were ovendried at 80°C, activated 1 h at 105 °C, then grounded to 100 mesh. This product was referred to as CTMAB-Bent.