Interlocked Dithi-Magnetospheres-Decorated MoS2 Nanosheets as Molecular Sieves and Traps for Heavy Metal Ions

Water remediation at minimal cost is the need of the day, as freshwater aquifers are declining at an alarming rate. To address this challenge, composite membranes is herein developed using a unique reversible addition-fragmentation chain transfer (RAFT)-synthesized copolymer as the active surface layer, a commercial reverse osmosis (RO) membrane serving as the support layer, and foamy molybdenum disulfide (MoS2) nanosheets decorated with dithi-magnetospheres acting as the interlayer. This strategy is adopted because the commercial RO membrane is effective toward desalination but is susceptible to fouling and biofilm. The foamy interlayer MoS2 nanosheets decorated with dithi-magnetospheres in the composite membranes minimize the additional resistance, both in terms of flow and also facilitate reversible action toward heavy metal removal. Further, the composite membranes exhibit a 7-log reduction in bacterial colonies for both gram-positive and gram-negative strains. A stringent and targeted action is also observed in terms of intracellular reactive oxygen species generation. In addition, excellent reversible antifouling with 98.5% flux retention ratio is observed. The average lead (II) removal at 50 ppm is 95.3% and the average arsenic (III) removal at 50 ppm is observed to be 96%. Thus, these membranes could be the next generation to advance sustainable systems for water remediation.