Removal Of Typical Pharmaceuticals Molecules From Water By Charged Composite Hollow Fiber Nanofiltration Membranes

Two different charged composite hollow fiber nanofiltration(NF)membranes(PEI-NF membrane and PIP-NF membrane)were prepared by interfacial polymerization using polyethyleneimine(PEI),piperazine(PIP)and trimesoylchloride(TMC)as functional monomers.The polysulfone/polyethersulfone(PS/PES)ultrafiltration hollow fiber membranes were used as supportion membranes.The separation performance of different charged NF membranes were characterized using inorganic salt solution.Then the rejection behaviors of the two NF membranes for six pharmaceuticals molecules including primidone,carbamazepine,sulfamethoxazole,atenolol,sulfadimidine and norfloxacin were also characterized in this study.At the same time,the adsorption kinetics of the pharmaceuticals molecules on the two charged NF membranes were investigated.The stability of the NF membranes was also studied.The saturation adsorption time of different pharmaceuticals molecules on each membrane surface did not show obviously difference,which is related with the molecular weight,charge and hydrophilicity of pharmaceutical molecules.The adsorption rate was very fast in initial adsorption stage(1-20 min)for PEI-NF membrane.After the pharmaceuticals molecules reached adsorption equilibrium,the rejection rates of primidone,carbamzepine,sulfamethoxazole,atenolol,sulfadimidine and norfloxacin by PEI-NF membrane were 85.6%,91.8%,79.9%,98.1%,93.3%,97.1%,respectively.The adsorption rate for PIP-NF membrane in initial adsorption stage(1-30 min)was also very fast.After the pharmaceuticals molecules reached adsorption equilibrium,the rejection rates of primidone,carbamzepine,sulfamethoxazole,atenolol,sulfadimidine and norfloxacin by PIP-NF membrane were 82.2%,85.4%,91.5%,79.1%,87% and 93.3%,respectively.The steric hindrance effect played a dominant role for the nanofiltration membranes removal neutral charged pharmaceuticals molecules.And the two NF membranes presented good stability in 12 hours continuously operation.The influence of operation parameters including the feed concentration,operation pressure,temperature,pH and ionic strength on pharmaceuticals' rejection behaviors for PEI-NF membrane and PIP-NF membrane were also studied.Effect of feed concentration,operation pressure,temperature on rejection rates of pharmaceuticals was not very obviously.With the change of pH value and ionic strength,rejection rates of pharmaceuticals molecules by two NF membranes changed obviously.The results were attributed to the pharmaceuticals' chemical properties,membrane pore size and surface charge,and the interaction between pharmaceutical molecules and membrane surface change due to the change of operation parameters.In this study,the removal behavior of pharmaceuticals by charged composite hollow fiber nanofiltration membranes was determined by the collaborative effect of steric hindrance and electrostatic repulsion.