Functionalized Graphene Oxide as an Adsorbent Material for Endocrine Disruptor 4-Octylphenol

Abstract

The widely used 4-octylphenol (OP) belongs to the group of endocrine disrupters (ED). However, it exerts potentially adverse effects on human health and the environment and has been detected in various environmental matrices. Adsorption is an effective treatment method for removing ED. This study analyzes the adsorption process of OP on graphene oxide (GO) on a bench scale and the central composite design was used for analyses of adsorption with four factors, namely, adsorbate concentration (100 to 120mg.L-1 COP), adsorbent concentration (0.2 to 3.4g.L-1 CGO), contact time (15 to 90min Ct), and pH (2 to 10). The results helped investigate adsorption capacity, adsorption kinetics pseudo-first order, pseudo-second order, Elovich equation, and intraparticle diffusion (IPD) and equilibrium conditions Langmuir, Freundlich, and Redlich-Peterson by mathematical models and showed 158.92mg.g-1 (120mg.L-1 COP, 0.2g.L-1 CGO, 90min Ct, and pH 2) maximum adsorption capacity. Regarding kinetics, Elovich equation best fitted the experimental data (R2 = 0.9961) and IPD indicated the adsorption process took place in the intraparticle and in the boundary layer. Redlich-Peterson model showed the best fit to the data (R2 = 0.9971) in the isotherms. The study demonstrated the adsorption of OP by GO in an aqueous solution can be used over a wide range of pH and contact times with no significant loss of efficiency.