Adsorption of 17 β- estradiol in graphene oxide through the competing methanol co-solvent: Experimental and computational analysis

Abstract

Currently, detecting endocrine disruptors in sewage treatment plants, rivers and drinking water is a matter of global concern. To minimize this public health problem, it is necessary to apply advanced treatments, such as adsorption, in water, with emphasis on the nano-adsorbent graphene oxide. In this work, the use of graphene oxide for adsorption of 17β-estradiol was evaluated experimentally and through computer simulation, varying the temperature and the proportion of co-solvent (methanol) in solution. The kinetic isotherms of adsorption were applied in computational simulations to evaluate the structural and electronic properties of the systems. The experimental results with 98:02% (m/m) of water:methanol at 288 K gave the maximum amount of 17β-estradiol adsorption, 169.49 mg/g, and the best fitting adsorption isotherm was Langmuir. A pseudo-second-order adsorption kinetics model was a better fit than a pseudo-first-order. In this proportion, the adsorption capacity of 17β-estradiol increases in the nanomaterial because methanol occupies active sites in graphene oxide. The theoretical results show that the interaction with graphene and the endocrine disruptor and graphene oxide and methanol occurred through physical adsorption due predominantly to π-π type interactions and hydrogen bonds between the systems. Therefore, graphene oxide is a promising material for removing 17β-estradiol in aqueous solution.