Enhanced removal of the endocrine disruptor compound Bisphenol A by adsorption onto green-carbon materials. Effect of real effluents on the adsorption process.

ABSTRACT

The high exposure to the endocrine disrupting compounds (EDC) in water represents a relevant issue for the health of living beings. The xenoestrogen Bisphenol A (BPA), a suspected EDC, is an industrial additive broadly used for manufacturing polycarbonate and epoxy resins. Due to its harmful effect in humans and the aquatic environment, an efficient method to remove BPA from wastewater is urgently required. The present work aims to study the adsorption of BPA from aqueous solutions onto carbonaceous materials, e.g., a synthesized carbon xerogel (RFX), a chemical-activated carbon from Kraft lignin (KLP) and a commercial activated carbon (F400) for comparative purposes. Batch kinetic and adsorption tests of BPA in ultrapure water were accomplished, finding higher adsorption capacities of BPA onto both F400 activated carbon (qsat = 407 mg g-1) and the biochar KLP (qsat = 220 mg g-1), versus to that obtained for the xerogel (qsat = 78 mg g-1). Furthermore, kinetic experiments revealed faster kinetic adsorption for RFX and KLP materials, achieving the equilibrium time within 24 h, attributed to their more-opened porous structure. Pseudo-first order, pseudo-second order, Elovich, intra-particle diffusion and film diffusion models were used to fit the experimental data. Thus, the BPA adsorption isotherms were analysed by Langmuir, Freundlich, Sips, Redlich-Peterson and Dual-site Langmuir (DLS) isotherm models.In addition, the influence of different aqueous matrices, such as a hospital wastewater, a wastewater treatment plant (WWTP) effluent and a river water, on BPA removal efficiency has been explored. These adsorption tests revealed a clear competitive effect between the target compound (BPA) and the natural organic matter content (NOM) present in the matrices for the active sites, resulting in a high decreasing of BPA adsorption removal.