亲水荷电超滤膜的制备及对腐殖酸的分离性能

为改善聚醚砜(PES)超滤膜的抗污染性能和提高对腐殖酸(HA)的截留率,以介孔二氧化硅(MS)为添加剂,采用相转化法制备了亲水性PES/MS复合超滤膜,并对膜表面进行荷电改性.研究了MS对膜的断面结构、表面化学性质和过滤性能的影响,考察了荷电改性PES/MS超滤膜对水中HA的分离性能以及溶液pH值、离子强度和钙离子浓度等因素对荷电膜超滤过程的影响.SEM表征结果显示,MS颗粒在PES/MS复合膜的表面分散均匀,膜孔的连通性改善.亲水荷电改性后,膜表面接触角由68°降至57°,zeta电位由-6.31mV降至-11.45mV,膜对HA的去除率由72%提高到95%,通量衰减率由29.8%减小到4.9%.结果表明,对PES超滤膜进行亲水荷电改性可有效提高对HA的截留率,同时减轻膜污染;另外,溶液的pH值、离子强度和钙离子浓度对荷电超滤膜的过滤性能有较大影响,调节合适的溶液环境可在提高截留率的同时,减轻膜污染.

Fabrication and humic acid separation performance of hydrophilic negatively charged ultrafiltration membrane

To improve the antifouling performance and enhance the humic acid (HA) removal rate of polyethersulfone (PES) ultrafiltration membrane, the mesoporous silica (MS) was incorporated in PES membrane by phase inversion method and the surface of PES/MS membrane was negatively modified. The effects of MS on the PES membrane structure, surface chemical property and filtration performance were studied. The HA separation property of negatively charged PES/MS membrane and the effects of pH value, ion strength and Ca2+ concentration on the filtration performance were also investigated. SEM images showed that MS particles dispersed evenly on the PES/MS surface and the membrane pore connectivity was improved. After the hydrophilic charged modification, the contact angle of PES membrane decreased from 68° to 57°, the zeta potential decreased from -6.31mV to -11.45mV; the HA removal rate increased from 72% to 95% while the flux decline rate decreased from 29.8% to 4.9%. Results indicated that hydrophilic charged modification on the PES membrane could be an effective way for better removal of HA and reduction of the membrane fouling; In addition, solution environment, including pH, ionic strength and calcium ion concentration, affecting HA filtration process could be adjusted to achieve higher removal rate and less fouling.