Construction of polyaniline/MXene/graphene oxide ternary nanohybrid for sequestration and reduction of hypertoxic Cr(VI) in water

Abstract

The anionic heavy metal contaminant chromium (Cr) is highly mobile, oxidizing, and carcinogenic, predisposing it to a range of biological health and environmental issue. Herein, polyaniline/MXene/graphene oxide ternary nanohybrid (PMG) with multiple types of functional groups and high efficiency of electron transfer capacity was synthesized by electrostatic self-assembly of polyaniline (PANI)-assisted MXene and graphene oxide (GO) two-dimensional nanoplates for the adsorption of hazardous Cr(VI). The charge transfer process promoted the polymerization of aniline on the surface of MXene, and the generation of PANI induced MXene and GO to intercalate with each other and ultimately ameliorated the over-negative potential of the MXene and GO composites. The adsorbent PMG exhibited the optimum adsorption effectiveness of 156.2 mg/g for Cr(VI) at pH = 2 and a sample dosage of 1 g/L. Isotherm and kinetic exploration experiments, combined with the findings of zeta potential, XPS, and first-principles calculations, indicated that approximately 89.3% of Cr(VI) was transformed into Cr(III) and anchored by PMG, revealing the adsorption mechanism to be probably a multilayered chemisorption involving redox reactions, electrostatic interactions, and complexation. The anti-interference experiments and cycling tests further confirmed the prominent application potential of PMG. This study provides feasible insights for remediating water contaminated with hexavalent chromium.