Adsorption of bisphenol A by TiO2-based organic–inorganic hybrid materials

Abstract

In this study, TiO2-P25 was modified with benzoic acid (BA) and 2-naphthalenecarboxylic acid (NCA), and subsequently used to adsorb bisphenol A (BPA). The relationship between the hydrophobicity of the modified TiO2 and the amount of BPA adsorbed was investigated. The equilibrium adsorption data were analyzed using the Langmuir, Freundlich, Dubinin–Radushkevich, Temkin, Harkins–Jura, and Halsey models. Additionally, TiO2 and TixZr(1-x)O2 of high specific surface area were synthesized via the sol-gel and solvothermal methods. The materials were modified using NCA and used to adsorb BPA. The surface properties of the adsorbent were investigated by Brunauer–Emmett–Teller surface area analysis, Barrett–Joyner–Halenda pore size analysis, CO2 temperature-programmed desorption, and CHN elemental analysis. The specific surface area of TixZr(1-x)O2 (252.1– 455.0 m2/g) was higher than that of TiO2 (157.6 m2/g) and the amount of NCA modified onto TixZr(1-x)O2 (1.106– 1.319 mmol/g) was also higher than that of TiO2 (0.405 mmol/g). The amount of NCA modification onto TixZr(1-x)O2 was promoted by surface base points. The maximum amount of BPA adsorbed was 22.4 mg/L, which was 5.86 times that of TiO2-P25, and approximately 90 % of the BPA was removed from a solution having an initial concentration of 100 mg/L.