Preparation And Application Of Nanofiltration Membrane For Organic Wastewater Desalination

In order to dispose the industrial effluents containing light molecular organic compounds more efficiently,nanofiltration(NF) polyamide composite membrane was prepared by interfacial polymerization on polysulfone(PSf) membrane.Different diamines were chosen as polymerization monomer and the effects of membrane preparation conditions such as monomers concentration in aqueous phase and organic phase,interfacial polymerization reaction time,temperature of heat treatment on the separation performance of composite membrane were also investigated.Meanwhile, based on the suitable NF membrane prepared for real dye industry wastewater treatment,the influences of feed composition,feed pH,temperature and operation pressure on dye wastewater NF process were studied.Finally,NF membrane stability and fouling in the continuous treatment process of dye wastewater were also evaluate&During NF membrane preparation,piperazine(PIP) and trimesoyl chloride(TMC) were chosen as reaction monomers in interfacial polymerization.As the concentration of PIP in aqueous phase was 0.43%(w/v),concentration of TMC in organic phase was 0.15%(w/v),reaction time was 60s,and temperature of heat treatment was 50.0℃,the performance of prepared NF membrane was best.The terephthalic acid(PTA) rejection of this membrane was higher than 97%and NaCl rejection of this membrane was less than 39%.This NF membrane was suitable for desalination of light molecular organics aqueous solutions.As the real dye wastewater was treated by NF process,the NF membrane was prepared on PSf-1 supported layer with 0.15%(w/v) PIP in aqueous phase and 0.1%(w/v) TMC in organic phase.The results showed that the concentration of salt and T acid,pH,temperature and operating pressure had a significant influence on the membrane separation performance.When the dye wastewater contained 3.0g/L T acid and 25.0g/L ammonium sulfate,feed pH was 5.0,operation temperature was 25.0℃and operation pressure was 1.5MPa,the permeate flux of NF membrane was more than 22 L/m~2h,the rejection of T acid was over 92.0%and the rejection of salt was less than 40.0%.These results could meet the requirements of NF process on dye wastewater treatment.