Preparation, Characterization and Adsorption Performance of Cetyl Pyridine Bromide Modified Bentonites

Benzoic acid removal is important for the water treatment and adsorption is an effective treatment process. Cetyl pyridine bromide-modified bentonites (CPB-Bent) and hydroxy-aluminum-pillared bentonites (Al(OH)-Bent) were prepared and characterized by XRD, FTIR and BET. Adsorption experiments were conducted on the adsorption of benzoic acid onto natural bentonites, sodium bentonites (Na-Bent), Al(OH)-Bent and CPB-Bent in batch experiments. Benzoic acid removal onto CPB-Bent is pH dependent and the optimum adsorption is observed at pH similar to 3.5. The adsorption rate was fast and equilibrium was established within 90-min. The adsorption rate of benzoic acid on CPB-Bent fit a pseudo-second order kinetics model well (R-2 = 0.999). The results were analyzed according to the Henry, Langmuir, Freundlich, and Dubinin-Radushkevich isotherm model equations. The adsorption data is well interpreted by the Langmuir isotherm model. Benzoic acid solution at a concentration of 0.5 mmol/L was adsorbed by CPB-Bent; and, the final adsorption efficiency was greater than 90%. The results show that benzoic acid adsorption capability of CPB-Bent is high with the maximum adsorption capability of 94.34 mg/g, which suggests that CPB-Bent is an excellent adsorbent for effective benzoic acid removal from water.