Tannic Acid-Functionalized MoS₂ and g-C₃N₄ Thin Film Lamellar Membranes for Improved Permeance and Rejection in Nanofiltration

Abstract

Design of lamellar membranes using nanomaterials of different dimensions has gained importance as they offer combined and synergetic properties that can significantly enhance the permeance and rejection. Herein, we report the fabrication of a lamellar thin film composite of a polyamide composite membrane via interfacial polymerization using 1T-molybdenum disulfide/ graphitic carbon nitride (1T-MoS 2 /g-C 3 N 4 ), synthesized by a one-pot solid state reaction. The developed nanofiller 1T-MoS 2 /g-C 3 N 4 (MC) had unresolved issues, namely, low stability, agglomeration, low processability, and poor compatibility when incorporated into membranes. A sustainable approach to functionalize the MC surface with low-cost, stable, and ecologically friendly tannic acid (TA), a polyphenol derived from plants and rich in −OH functional groups, has significantly addressed the aforementioned issues. The hydrophilic nature and strong negative charge of TA produce a dense network on the membrane surface, inducing nanofiltration ability, in addition to offering efficient permeance. The optimal loading of this functionalized composite in the membrane resulted in an 18.4% NaCl rejection while achieving twice the permeance (17.7 L m −2 h −1 bar −1 ) compared to that of the non-TA-treated membranes. Divalent salts of sodium and magnesium sulfate show rejection up to 97 and 95%, respectively, while dye molecules of Congo red (696.7 Da) and methylene orange (327.3 Da) show >94% rejection, all with very good permeance. The robust and economical technique of one-pot synthesis of nanofillers together with easy functionalization rendered a very strong, tough, high antifouling thin film nanocomposite membrane that could practically be applied in desalination applications. KEYWORDS: 1T-MoS 2 /g-C 3 N 4 , tannic acid, thin film membranes, salt and dye rejection, wastewater treatment

Highly Permeable and Fouling-Resistant Polyamide Nanofiltration Membranes with Embedded Boron Nitride Nanosheets for the Purification of Water

“…The morphology and structure of PA can be tuned by regulating the diffusion rate of amine monomer at the interface between aqueous and organic during the IP reaction . With the development of nanoscience, many nanomaterials such as silica, TiO 2 , boron nitride quantum dots (BNQDs), carbon nanotube (CNT), GO, MXene, , and MoS 2 have been introduced into IP process to modify the structure of the PA network. Furthermore, nanovoids formed by the interfaces between the nanofillers and polyamide can supply extra transport channels for water molecules, which provide a significant role in improving the permeance of NF membranes. , Nonetheless, some nanoparticles are easy to aggregate and have poor compatibility with PA, − leading to the declined selectivity and antifouling capability of NF membranes due to the generation of nonselective defects .…”