Preparation of three-dimensional 2-mercaptothiazoline modified GO aerogel for selective adsorption of Cu2+ in aqueous solution

Abstract

A novel 3-dimensional graphene oxide/2-mercaptothiazoline (3D GO-MT) aerogel was prepared by using GO and MT which contains heteroatoms (nitrogen-, sulfur-) through a facile hydrothermal assembly process and a following freeze-drying technology. The effects of hydrothermal reaction temperature and GO-to-MT mass ratio on the physicochemical properties of the composites were investigated. The removal of Cu2+ from aqueous solution by 3D GO-MT aerogels was evaluated. The results showed that the composite (GO-MT1:3/100 °C) with GO-to-MT mass ratio of 1:3 prepared at 100 °C had the highest adsorption capacity for Cu2+ (0.5299 mmol g−1). In a bicomponent system of Cu2+/Pb2+, GO-MT1:3/100 °C exhibited higher adsorption selectivity for Cu2+. And the distribution coefficients K of GO-MT1:3/100 ° C for Cu2+/Y3+, Cu2+/Nd3+ in the bicomponent systems were 0.6224 and 0.1253, respectively. The morphology and composition of GO-MT1:3/100 °C, as well as the adsorption mechanism for Cu2+ were investigated by scanning electron microscopy, Brunauer-Emmett-Teller, elemental analysis, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The presence of nitrogen and sulfur on MT heterocycle promoted the possible assembly of MT with GO through π-π stacking and hydrogen bonding interactions. Additionally, the existence of these heteroatoms in MT dominated the metal-chelate affinity of 3D GO-MT aerogel for selective adsorption of Cu2+. The fitted data of kinetics and thermodynamics showed that the adsorption process followed linear pseudo-second-order kinetics and linear Langmuir isotherm model. The adsorption process is non spontaneous and endothermic. The adsorption mechanism of GO-MT1:3/100 °C for Cu2+ involves coordination, cation-π electron interaction, electrostatic attraction and other intermolecular interactions. 3D GO-MT1:3/100 °C can be used as an adsorbent material for selective adsorption/enrichment of Cu2+ in aqueous solution.