Synthesis of a novel magnetic composite based on graphene oxide, chitosan and organoclay and its application in the removal of bisfenol A, 17α-ethinylestradiol and triclosan

Journal of environmental chemical engineering(2021)

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A new nanocomposite was synthesized from graphene oxide, magnetic chitosan and organoclay (GO/mCS/OC). Its application as an adsorbent was investigated for the removal of emerging contaminants such as bisphenol A (BPA), 17α-ethynylestradiol (EE2) and triclosan (TCS). These contaminants, even at low concentrations, cause damage to aquatic biota and have been attracting the attention of researchers around the world. The synthesis of nanocomposite comprised the preparation of GO through hummers method, followed by the aggregation of magnetic chitosan and organoclay particles. These adsorbent materials were characterized using FTIR, XRD, SEM, EDS, TGA, VSM and zeta potential. Furthermore, their adsorptive capacities were evaluated in batch system. The synthesized nanocomposite exhibited satisfactory performance and similar to that of the precursor organophilic clay under the conditions evaluated. TCS was easier to be removed, followed by EE2 and BPA, with removal percentages of about 98, 72 and 58% and adsorptive capacities of about 40, 30 and 20 mg g -1 , respectively, when using the nanocomposite. In order to unveil the chemical reactivity of the approached contaminants at a molecular level, density functional theory (DFT) was evaluated by calculating molecular chemical descriptors and evaluating the electrostatic potential maps. The chemical reactivity corroborates the affinity assays, showing a more effective adsorption of the most reactive molecule, which was the TCS. The synthesized nanocomposite performed well in removing emerging contaminants and proved to be a good alternative in the treatment of contaminated effluents. • Successful sequential aggregation of GO, mCS and OC. • High removal rates up to 98.6% of BPA, EE2 and TCS. • Adsorption capacity ranged from 19.7 – 40.7 mg g -1 for the evaluated contaminants. • DFT improved the understanding of BPA, EE2 and TCS behavior on a molecular level. • The materials showed good performance removing emerging contaminants.
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