One-step hydrothermal synthesis of CTAB-modified SiO₂ for removal of bisphenol A

A stable SiO₂ material marked as CTAB-Ms(x) was synthesized by a novel sol-gel method. It was modified with hexadecyl trimethyl ammonium bromide (CTAB), which resulted in high adsorption capacity. Its microstructure and surface functional groups were characterized by scanning electron microscope, transmission electron microscope and Fourier transform infrared. The results showed that CTAB-Ms(x) had a core/shell structure in which the core was a CTAB micelle and the shell was SiO₂. The prepared material was applied to adsorb bisphenol A (BPA). Pseudo-first-order kinetics equation, pseudo-second-order kinetics equation, Langmuir adsorption isotherm model, Temkin adsorption isotherm model, and thermodynamic equations were used to fit and analyze the experiment results. The theoretical maximum adsorption capacities calculated according to linear and non-linear forms of the Langmuir isotherm were 370.37 mg·g^-1 and 198.80 mg·g^-1, and the adsorption equilibrium time was 120 min. A mechanism study showed that the high adsorption capacity was attributed to the solubilization effect of the CTAB micelle.