Removal of trace organic contaminants by melamine-tuned highly cross-linked polyamide TFC membranes. (January 2020) - Rastgar, Masoud
Abstract: In recent years, forward osmosis (FO) has represented numerous potential applications in safe water production. In this study, we improved the performance of FO thin film composite (TFC) membranes for the removal of trace organic compounds (TOrCs) by tuning the chemistry of its top active layer. The TFC membranes were synthesized by interfacial polymerization (IP) reaction between amine-containing monomers, e.g., meta -phenylene diamine (MPD) or para -phenylenediamine (PPD), and an acid chloride monomer, e.g., trimesoyl chloride (TMC). Owing to three free amine functionals over main core, melamine was used in the amine monomers solution to increase cross-linking among polyamide chains. Chemical and morphological characterization of the prepared membranes confirmed that melamine was successfully incorporated into the chemical structure of the top PA layer. Two agricultural toxic materials (atrazine and diazinon) were used to investigate the capability of the newly fabricated membranes in the removal of TOrCs. The obtained results showed that melamine-improved FO membranes provided higher atrazine and diazinon rejections in two different FO membrane configurations, including active layer facing feed solution (ALF) and active layer facing draw solution (ALD). The highest rejections of both diazinon (99.4%) and atrazine (97.3%) were achieved when the melamine modified MPD-based membrane served in ALF mode with 2 M NaCl as a draw solution. Graphical abstract: Image 1 Highlights: Novel highly-crosslinked thin film composite membranes for forward osmosis process. The synthesized membranes were used for the removal of trace organic contaminants from wastewater. The thickness, morphology, and roughness of common FO membranes was tuned by the addition of highly functional melamine. Melamine-improved FO membranes provided higher efficiency for the removal of agricultural wastes than conventional membranes.