Crosslinked hydrogels of polyethylenimine and graphene oxide to treat Cr(VI) contaminated wastewater

Abstract

This research papers reports the synthesis of graphene oxide (GO) and polyethylenimine (PEI) based crosslinked nanocomposite hydrogels (GO/PEI-NCH) for its application as potential adsorbent to treat Cr(VI) polluted water. To synthesize GO/PEI-NCH, graphene oxide was initially amine functionalized using 3-aminopropyltriethoxysilane (APTES) which was subsequently grafted with PEI. Successful functionalization of GO with APTES and the crosslinked hydrogel network formation was evidenced by characterizing samples using SEM, X-ray diffraction, Raman, FTIR and TGA. Approximately 97 percent Cr(VI) was adsorbed from the chromium solution of 50 mg/L concentration at pH 2 with 0.5 g/L mass of GO/PEI-NCH. Further, adsorption isotherm correlated well with Langmuir model and predicted homogenous monolayer adsorption with the adsorbent having energetically identical binding sites. GO/PEI-NCH exhibited 443.8 mg/g maximum adsorption capacity for Cr(VI). Adsorption kinetics was well defined using pseudo-second-order model. GO/PEI-NCH could be easily and efficiently regenerated using HCl solution and it exhibited good stability and reusability for ten continuous adsorption-desorption cycles. Therefore, GO/PEI-NCH is a promising candidate to treat Cr(VI) ions contaminated wastewater.