The energy consumption of reverse osmosis (RO) has declined significantly since inception and to further decrease the energy consumption is a challenging task. The present article demonstrates the novel method to increase the membrane productivity and reduce energy consumption of desalination. Thin film composite RO (TFC RO) membrane was subjected to 2000 mg/L sodium hypochlorite for 1 h followed by varying concentrations of chitosan and glutaraldehyde for 1 h each to make a hydrophilic supra‐molecular assembly of linear polysaccharide over the polyamide layer. RO membrane exposed to 1000 mg/L chitosan and glutaraldehyde each reported 180% increase in water‐flux with about 2.7% increase in divalent ion rejection as compared to virgin TFC RO membrane. The superior performance of the membrane was explained by increased hydrophilicity as shown by decline in contact angle from 46.37° to 29.87°, increase in surface area ratio from atomic force microscope image analysis, and modification in chemical structure of polyamide from attenuated total reflectance Fourier transform infrared spectroscopy. It was further investigated that curing of glutaraldehyde treated membrane resulted in decreased water‐flux because of increase in crosslink density. Thus, an ultra‐low energy RO process can be developed based on polyamide–chitosan–glutaraldehyde membrane. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45971.

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a b s t r a c tA novel zeolite-polysulfone composite ultrafiltration membrane was synthesized. 50-1500 mg/L zeolite nanopowder was added in 15% (w/v) polysulfone solution in N,N-Dimethylformamide solvent. The membrane was formed by phase inversion process. It was found that the membrane became more hydrophilic in nature as manifested by 134.3% increase in pure water permeability at 50 psig pressure of 700 mg/L zeolite nanopowder composite as compared to polysulfone membrane. It was also proven by decline in contact angle from 91.08° to 59.89° for the same. The membrane selectivity performance was also improved as exhibited by albumin rejection from 86.39% to 95.31% for the nanocomposite formed with 700 mg/L zeolite nanopowder. Fouling and flux decline were monitored with 5000 mg/L albumin concentration at 50 psig pressure and it was found that the flux decline at the end of 8th hour was 22.41% for 700 mg/L zeolite nanocomposite as compared to 39.8% for virgin polysulfone membrane. However, on increasing nanomaterial loading to 1500 mg/L in the composite, the pure water permeability declined about 19%, contact angle increased from 59.89° to 81.55°, albumin rejection decreased from 95.31% to 80.55% as compared to the nanocomposite with 700 mg/L nanomaterial loading. SEM and AFM images were taken of the virgin polysulfone and the nanocomposite. It was found that at higher concentration, e.g., 1500 mg/L the nanomaterial agglomerates and thus the incentives of using nanomaterial is attenuated at higher concentration. It was found that 700 mg/L zeolite nanomaterial loading was optimum for advanced water treatment applications as the selectivity of membrane for protein separation and the pure water permeability are the highest. Thus, zeolite nanocomposite can work as a low-fouling, high flux membrane for ultrafiltration applications.

Thin Film Composite Reverse Osmosis (TFC RO) membranes have undergone significant changes since inception; particularly the top polyamide layer has been tuned for optimal performance. The present paper demonstrates the novel approach to alter the polyamide membrane performance by subjecting it to ionic liquids. Ionic liquids 1-Butyl-3-Methylimidazolium Chloride [BMIM][Cl], 1-Methyl-3-Octylimidazolium Chloride [C 8 MIM][Cl] and 1-Butyl-3-Methylimidazolium Bromide [BMIM][Br] were used to alter the membrane performance. About a 6.5% increase in MgSO 4 rejection and about an 87% increase in water-flux were noted when the membrane was subjected to 3000 mg/L [BMIM][Cl] after 2000 mg/L sodium hypochlorite each for 2 hours. Also, the decline in contact angle from 52.86 o to 43.12 o by this treatment demonstrated higher hydrophilicity. Atomic force microscope images showed a decline in surface roughness with the treatment. Scanning electron micrographs were taken to understand the changes in morphology of thin film composite reverse osmosis membranes with ionic liquid treatment. Attenuated total reflectance, infrared spectroscopy and nuclear magnetic resonance analysis were done to evaluate the changes in chemical structure and it was found that the treatment resulted in chemical structural modification of thin film composite reverse osmosis membranes with ionic liquid treatment.