Fabrication of a MoS2@PAN composite membrane for efficient removal of toxic Cr(VI)

Effectively removing toxic Cr(VI) from complex wastewater remains a considerable challenge. Conventional membrane technologies face a trade-off between rejection efficiency and permeance, whereas single adsorption techniques using nanomaterial often result in adsorbent loss and complicated recovery during Cr(VI) treatment. In this study, molybdenum disulfide (MoS2) nanosheets, renowned for their efficient adsorption of heavy metals, were integrated into a polyacrylonitrile (PAN) membrane to fabricate a high-performance MoS2@PAN composite membrane using the nonsolvent-induced phase separation method. The MoS2 nanosheets were uniformly distributed in the PAN matrix, significantly enhancing the membrane's hydrophilicity and antifouling properties even in the presence of organic pollutants. Batch experiments demonstrated that the MoS2@PAN membrane exhibited superior removal efficiency for Cr(VI) under acidic conditions; The removal process was spontaneous and endothermic, with higher temperatures facilitating Cr(VI) removal. The results from the isotherm and kinetic fitting indicated that the membrane's maximum removal capacity reached 143 mg/g at 298 K, with the adsorption rate being governed by intraparticle diffusion. Additionally, the membrane displayed remarkable selectivity for Cr(VI) removal, maintaining high efficiency even in the presence of elevated concentrations of interfering ions. In a simulated membrane filtration system, MoS2@PAN demonstrated effective treatment capabilities for up to 6000 L/m2 of Cr(VI). Furthermore, the material exhibited efficient regeneration when treated with a 0.5 M HCl solution, sustaining a removal efficiency of approximately 92 % after 10 cycles of use. This study provides valuable technical insights for the effective removal of toxic Cr(VI) from complex wastewater.