New insights into bisphenol a removal from water applying experimental and theoretical studies

Abstract

Bisphenol A (BPA) is used worldwide as a monomer in the production of polycarbonates and epoxy resins. It has been receiving growing attention over the years, as exposure to even low concentrations of this endocrine disruptor is being linked to serious health problems. This study aims to investigate the efficiency of powdered activated carbon (PAC) in removing BPA from water, as well as to apply a computational simulation to understand the behavior of BPA in solution and its interaction with a generic carbonaceous surface. In the adsorption studies, the mass of adsorbent (0.01–0.04 g) and the solution pH (2–12) were varied in order to understand their influence over the adsorption capacity (qe) of PAC. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion were employed to evaluate kinetic data. Langmuir, Freundlich, Dubinin–Radushkevich, and Redlich–Peterson isotherm models were applied. A theoretical study using density functional theory (DFT) showed that adsorption is mainly caused by C–H…O, C–H…π, lone-pair…π and π…π interactions. Equilibrium was reached after 120 min, with PAC removing a total of 96.68% of BPA. The best condition was achieved using 0.01 g at pH 9 and 298 K (246.20 mg/g). Good fittings to Dubinin–Raduschkevich (R2 = 0.985) and to Langmuir (R2 = 0.925) models were achieved, with a calculated maximum monolayer adsorption capacity (qmax) of 367.88 mg/g.