Polyvinylpyrrolidone and polyacrylamide intercalated molybdenum disulfide as adsorbents for enhanced removal of chromium(VI) from aqueous solutions

With the rapid expansion of industrialization, it is inevitable that heavy metal ion (such as chromium, Cr(VI)) is released into the ecological systems, which has become a potential threat to public health. Herein, polyvinylpyrrolidone intercalated molybdenum disulfide composites and polyacrylamide intercalated molybdenum disulfide composites were synthesized for the efficient removal of Cr(VI) from aqueous solutions. The sorption of Cr(VI) on the composites was studied by batch technique and the macroscopic sorption results revealed that the removal of Cr(VI) was strongly dependent on ionic strength and pH. The removal capacities of Cr(VI) achieved 142.24 mg/g on PVP/MoS2 and 84.91 mg/g on PAM/MoS2 at pH= 5.0. The thermodynamic study indicated that the interaction was a spontaneous and endothermic process. According to the batch experimental results combined with XPS spectra analysis, it can be considered that the interaction of Cr(VI) with the composites was that Cr(VI) ions were fixed on the composite surfaces by electrostatic attraction and then entered into the interlayer and combined with amide groups at the interlamination of the composites. The findings can provide a new perspective for the rational design of MoS2 composites with high performance and excellent chemical stability for Cr(VI) removal in extreme conditions, which would not cause secondary pollution.