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

Abstract

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.

In situ assembly of a graphene oxide quantum dot-based thin-film nanocomposite supported on de-mixed blends for desalination through forward osmosis

“…To determine the bulk hydrophilicity of the membranes, water uptake was determined as per our previous reports. 3,15 Five equal-sized membranes of 0.63 cm 2 area were weighed aer vacuum drying. Following this, they were soaked in distilled water for 24 h. The excess water was removed using lter paper, and their weight was measured.…”

“…4 In this context, reusing desalinated water for practical applications seems a feasible solution since nearly 71% of the earth is water, and 96.5% of that water is present in oceans. 3 Compared to techniques such as thermal distillation, electro-dialysis, and evaporation, membrane-based desalination is the most economical and cost-effective process. [5][6][7] The pump cost associated with this process is much lower than the distillation cost.…”

The Key Role of Modifications in Biointerfaces toward Rendering Antibacterial and Antifouling Properties in Polymeric Membranes for Water Remediation: A Critical Assessment

“…A hydrophilic membrane, however, has high surface tension and is capable to form hydrogen bonds with water molecules at the interface thus reconstructing a thin boundary between the membrane and foulants. [79,[81][82][83][84] Quaternary ammonium compounds (QACs), [52,[85][86][87] sulphonium, [88] phosphonium, [51,[89][90][91] and biguanide [92,93] based modifications have been reported to exhibit very good antibacterial properties. [78] The other approach is to impede bacterial growth and its flustering or repel them from the surfaces using engineered surfaces that have an inherent charge on them.…”

“…These agents permeabilize the bacterial cell membrane and lead to intracellular leakage of bacterial cells. [79,[81][82][83][84] Quaternary ammonium compounds (QACs), [52,[85][86][87] sulphonium, [88] phosphonium, [51,[89][90][91] and biguanide [92,93] based modifications have been reported to exhibit very good antibacterial properties. There are leaching based approaches as well for the rendering of the surface antibacterial and impede the growth of microbes like Ag, [94][95][96] Cu, [97][98][99] etc., which have shown to to promise bactericidal property when tethered with polymeric membranes.…”

‘Template-free’ hierarchical MoS2foam as a sustainable ‘green’ scavenger of heavy metals and bacteria in point of use water purification

“…[16][17][18][19] Among these materials, two-dimensional (2D) layered materials have been extensively researched in the eld of water decontamination due to their excellent salt rejection and antibacterial properties. [20][21][22][23][24][25][26][27][28][29][30] In the recent past, most of the research has focused primarily on graphene oxide (GO) based membranes for water purication. These membranes have suffered from signicant limitations such as: (i) introduction of friction against moving water compromising the structural integrity of the membrane over time; (ii) sensitivity towards changing pH; and (iii) probable hydration of the surface functional groups on GO leading to increases in the interlayer spacing and therefore, reduction in membrane selectivity to ions.…”