The commercial reverse osmosis (RO) membrane surface was chlorinated with the sodium hypochlorite solution. Then the chitosan as a polycation electrolyte was deposited on the chlorinated RO membrane surface with the help of electrostatic adsorption. With the aim of preparing high flux and high salt rejection RO membrane

the effects of solution pH

chlorination time

sodium hypochlorite concentration

chitosan concentration and deposition time on membrane performance were systematically studied. The water flux and the salt rejection were measured at 1.55 MPa and (298±1) K for a feed NaCl concentration of 2000 μg·g-1. The results showed that

compared to the original RO membrane

the water flux of the chlorinated membrane increased by 19.89% when the chlorination solution pH=9

the chlorination time was 30 min and the chlorination concentration was 1000 mg·L-1. A slightly increase of the salt rejection was also observed. Further modification of chitosan deposition on the chlorinated membrane surface showed that the membrane surface hydrophilicity was enhanced. When the chitosan concentration was 0.1%(mass) and the deposition time was 30 min

the water contact angle of the membrane surface was 34.88° and the salt rejection improved to 99.56%. The water flux of the deposition modified membrane reached 60.55 L·m-2·h-1

which was nearly maintained the same as the chlorinated RO membrane above. These results indicated that both the water flux and the salt rejection of the modified commercial RO membrane improved after the surface modification through chlorination and chitosan deposition.