Solid-State Synthesis of Organoclays: Physicochemical Properties and Application for Bisphenol A Removal from Aqueous Solutions

Abstract

The solid-state intercalation of organoclays, by using surfactants bromide salts (n-C12H25(CH3)3NBr, n-C14H29(CH3)3NBr, n-C16H33(CH3)3NBr and n-C12H25)2(CH3)2NBr) at different levels of the cation exchange capacity (CEC), was reported. According to XRPD data, the basal spacing of the smectite phase unit cell increased systematically up to >38 Å at 2.0-CEC of surfactants loading, indicating that they entered into the smectite interlayers and were arranged parallel to the layers at low concentrations and nearly vertical at high ones. Organoclays FTIR spectra showed a drop in the water band intensities at around 1630 and 3400 cm−1, and new specific bands close to 2920 and 2850 cm−1 were assigned to the asymmetric and symmetric stretching of the surfactants CH2 groups, respectively. Various factors, impacting bisphenol A (BPA) removal from water, were estimated in batch studies. It is shown that both physisorption and chemisorption describe the BPA sorption, and the pseudo-second-order kinetics and Langmuir isotherm fit better the BPA sorption results. The adsorption capacities of the organoclays are ranged from 88 to 127 mg/g at ambient temperature and in acidic solution. The effect of pH on the adsorption showed a remarkable drop in the quantity of adsorbed BPA when the pH is greater than 10 (pH ≥ 10).