Low-energy reverse osmosis membrane with high boron rejection by surface modification with a polysaccharide

The present paper aims at producing a high-performance low-energy reverse osmosis membrane by modifying the polyamide layer with potassium persulphate, chitosan, and methacrylic acid and sodium hypochlorite treatment. A supramolecular assembly of chitosan was made on the polyamide layer with methacrylic acid to increase the permeate flux. The concentrations of chitosan and methacrylic acid were varied to investigate the best combination of treatment to achieve superior performance. The membrane treated with 1000 mg/L chitosan and 4 % methacrylic acid showed permeate water-flux 3.2 times that of virgin TFC RO membrane with a similar to 2 % decline in salt rejection and a boron rejection of 97.45 % at pH 10. This membrane demonstrated energy saving of 68.78 % as compared to virgin thin film composite reverse osmosis membrane. Membranes were tested for hydrophilicity by contact angle analysis, surface charge by zeta potential analysis, morphology evaluation by scanning electron microscope, surface features by atomic force microscope, and chemical structural changes by attenuated total reflectance infrared spectroscopy. Significant enhancement in membrane performance was observed by surface modification to achieve ultra-low energy reverse osmosis process development.