High flux separation membranes based on cellulose gel layer modification and their dye/salt separation properties
The large amount of salt-containing dye wastewater generated by the textile industry has become one of the global environmental problems,so there is an urgent need for dye/salt selective separation membranes with high flux for wastewater treatment.In this study,poly(vinylidene fluoride)(PVDF)-based membranes were prepared by non-solvent-initiated phase separation(NIPS),carboxymethylcellulose was introduced on the membrane surface through the co-deposition reaction of dopamine and carboxymethylcellulose,and then a carboxymethylcellulose gel layer with three-dimensional network structure was constructed on the surface of the membrane by using layer-by-layer cross-linking,and inorganic silver nanoparticles were introduced in situ in the process of the preparation of the gel layer,which could play a role of backbone support to avoid the collapse of the gel layer under pressure,and the construction of the functional gel layer synchronously enhanced the permeability and selectivity of the membrane.It was found that M-CMC-Ag membranes prepared at a carboxymethylcellulose concentration of 1 g/L were superior in all aspects of performance,and its water flux reached 275.11 L/(m2·h),and in the separation test of the binary system of dye/salt at different concentrations(Congo red/NaCl mixture solution),the rejection rate of the dye was more than 95％,and the rejection rate of the inorganic salts was less than 9.5％.The M-CMC-Ag membrane was well stabilised in the cycling test of the dye solution and maintained a permeate flux higher than 285 L/(m2·h)for the cycling test of the Congo red solution.
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