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Membrane based desalination is the proven and established technology for mitigating the increasing water demand. The high flux membrane will require lower pressure to produce the given quantity of water and therefore will consume lower energy. The present paper demonstrates the novel method to produce high flux membrane by surface modification of thin film composite reverse osmosis (TFC RO) membrane. TFC RO membrane was exposed to sodium hypochlorite solution of 1250 mg/l for 30 minutes and 60 minutes at ph 11.0, followed by 1000 mg/l Chitosan for 60 minutes at pH 2.5 and the solute rejection/flux were monitored. It was observed that there is upto 2.5 times increment in flux with ca. 3% increase in solute rejection in case of chitosan treated membrane. Although, the flux increase is more in longer sodium hypochlorite treated membrane, the decline in solute rejection was also significant. The membrane samples were characterized by Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) to understand the chemical structural changes in the membrane, atomic force microscope to understand the morphological changes on membrane surface, zeta potential for surface charge and contact angle analysis to understand the change in hydrophilicity. The % rise in trans-membrane flux per o C rise in feed water temperature was more in case of chitosan modified membrane as compared to virgin TFC RO membrane. The higher temperature sensitivity makes it a good candidate for solar powered reverse osmosis where, low grade thermal energy can be utilized to increase the feed water temperature and higher temperature feed water gives more pronounced advantage in trans-membrane flux. Introduction:Thin film composite RO membrane has found numerous applications in desalination and water reuse. Research and development effort in improving its solute rejection and flow performance of the membrane has made the RO membrane versatile for diverse applications. A thin film composite RO membrane consists three layers: the bottom support

Surfactant-induced coagulation of agarose from alkali-treated Gracilaria dura seaweed extract (SE) is reported.

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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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Thin film composite reverse osmosis (TFC RO) membrane is widely used in desalination and water reuse applications. With increasing capacity of Reverse Osmosis desalination all over the world, the increasing green‐house gas emission for the required power is a cause of concern. TFC RO membrane is composed of the top polyamide layer over which, the linear polysaccharide such as chitosan can bind after activating the surface with oxidizing agent. The present paper analyzes the novel protocol of controlled oxidation of TFC RO membrane by exposing the same to potassium per sulfate with varying concentration of chitosan followed by sodium hypochlorite and sodium hypochlorite followed by potassium per sulfate with varying concentration of chitosan. The optimum performance was obtained when TFC RO membrane was exposed to 1% potassium persulfate with 1000 mg/L chitosan solution followed by 1000 mg/L sodium hypochlorite. Reversing order of the treatment resulted in the decline in permeance of the membrane. The reason of improvement in permeance is super‐hydrophilic surface formed by oxidation of chitosan over polyamide surface. Thus, this article demonstrates the novel protocol of significantly improving the flux of TFC RO membrane and thereby reducing the energy consumption. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45026.