Effective adsorption of the endocrine disruptor compound bisphenol a from water on surface-modified carbon materials

Abstract

Carbon-based adsorbents, e.g., xerogel (RFX) and lignin-based activated carbon (KLP) were characterized and tested for the adsorption of the endocrine disrupting compound Bisphenol A (BPA) from water. Then, pristine materials were modified following mechanical, chemical and thermal treatments. Pristine RFX showed a more-opened porous structure, enhancing the adsorption kinetic, c.a. 24 vs. 48 h equilibrium time, for RFX and KLP samples, respectively. Thus, RFX adsorption capacity decreased in comparison to that obtained for KLP (qsat = 78 vs 220 mg g−1). Thus, a clear correlation between micropore volume (Vmicro) and specific surface area (SBET) with BPA adsorption capacity could be established; so, an increment of BPA adsorption capacity was observed with an increase in both textural parameters. Moreover, the dominant sorption mechanism seems to be chemisorption; and DSL isotherm model was found the most suitable for the fitting of BPA adsorption isotherms. Generally, the presence of oxygenated/nitrogenated-groups on carbon surface led to a decrease in BPA adsorption capacity due to the decrease in π-π dispersive interactions and pore blocking phenomena. Finally, an increment in BPA adsorption capacity up to 135 mg g−1 (73% higher than that obtained for the pristine material) was obtained with the sample treated at high temperature.