Development of high-performance CuBTC MOF-based forward osmosis (FO) membranes and their cleaning strategies

Abstract

Though the forward osmosis (FO) process has been primarily accepted for desalination and wastewater treatment, it still faces significant challenges of (i) low water flux and high reverse solute flux and (ii) membrane fouling. In the present study, a new thin film composite (TFC) FO membrane was prepared by interfacial polymerization of chitosan biopolymer and trimesoyl chloride (TMC) as a separation layer and porous CuBTC MOF embedded polyethersulfone (PES) as the support layer to increase transport and antifouling properties. When compared to the bare membrane (Jw: 26 LMH, Js: 0.12 GMH) and similar literature reported membranes, the optimized FO membrane with 0.5 wt % CuBTC (Cu@FO-0.5) exhibits higher water flux (Jw: 58 LMH) with low reverse salt flux (Js: 0.57 GMH). This improvement is due to the additional pathways for water transportation due to CuBTC MOF. The modified membrane also had a reduced structural parameter (S), a lower reverse salt flux, and increased water wettability. Various physical and chemical membrane cleaning agents were studied to eliminate organic (algae) and inorganic (clay) foulants added to synthetic feed wastewater. The selected cleaning agents were later studied in series and in combinations for both foulants. Chemical cleaning showed higher water flux recovery than physical cleaning and obtained similar results for water collected from natural sources (river, reservoir, and pond). The findings suggest that Cu@FO-0.5 FO membranes integrated with reverse osmosis could be an effective technology in treating drinking water and wastewater sources.