Preparation Of High Flux And Anti-bacterial Reverse Osmosis Membranes

Reverse osmosis(RO)technology as an important membrane separation technology has been widely applied in seawater/brackish water desalination,sewage purification and reclamation,ultrapure water preparation,and so on.The water flux and anti-bacterial property,which have important influence on the cost,water production efficiency and operation stability of RO systems,are important indexes for the evaluation of RO membrane performance.In this work,for the RO membranes prepared by interfacial polymerization,the physical and chemical structure of polyamide active separation layer was optimized via adding additives in the water phase solutions,and thus the water flux and/or anti-bacterial property of the RO membranes were enhanced.The 2-MI modified RO membranes were fabricated by adding 2-methylimidazole(2-MI)into water phase solution.With the increase of 2-MI concentration in water phase solution,the water flux of modified membranes increased,and the salt rejection firstly remained nearly unchanged and then decreased gradually.Compared with the virgin membrane,when the concentration of 2-MI in the water phase solution was 0.8 wt%,the polyamide(PA)active separation layer of the modified membrane had smaller thickness and contact angle.Meanwhile,the water flux and salt rejection of the modified membrane were 76.1 L/(m2·h)and 98.8%,respectively.In addition,the thermal stability,pressure-resistance and long-time continuous operation experiments showed that the modified membranes had good structure and performance stabilities.The tobramycin(TOB)modified RO membranes were prepared by the interfacial polymerization between two water phase monomers(m-phenylenediamine(MPD)and TOB)and an organic phase monomer(trimesoyl chloride(TMC)).Compared with the virgin membrane,when the concentration of TOB in water phase solution was 0.75 wt%,the water flux of the modified membrane increased 20.2%,and the salt rejection remained nearly unchanged.In addition,the modified membrane had durable and efficient anti-bacterial activity.And after contacting with modified membrane surfaces for 1 h,the mortalities of Gram-negative E.coli and Gram-positive B.subtilis were 99.2%and 99.3%,respectively.