A negatively charged loose nanofiltration membrane by blending with poly (sodium 4-styrene sulfonate) grafted SiO2via SI-ATRP for dye purification

Abstract

© 2015 Elsevier B.V. All rights reserved. Silica spheres in nanoscale were prepared via sol-gel method and then sodium 4-styrene sulfonate was grafted onto the surfaces of SiO2(PSS-SiO2) by surface-initiated atom transfer radical polymerization (SI-ATRP). Then, a negatively charged loose SiO2-PSS/polyethersulfone (PES) nanofiltration membrane with high flux was fabricated via phase inversion method. FT-IR and TEM results showed that SiO2nanoparticles were synthesized and modified successfully. GPC results further proved the "living"/controlled behavior of SI-ATRP. The morphology, hydrophilicity of the membranes were investigated by SEM, static water contact angle and water ratio. The results revealed that the surface hydrophilicity and water permeability of hybrid membranes were greatly improved after adding SiO2-PSS and thus may enhance fouling resistance to a certain extent. The salt permeation and separation of dye/salt mixture of the hybrid membranes were significantly superior to the pure PES membrane, and the order of permeation for different salt solutions was NaCl > MgCl2> MgSO4> Na2SO4. When the content of SiO2-PSS was 3.0 wt%, the hybrid membrane showed optimal performance with IEC value of 0.07 mmol/g and pure water flux of 269.5 L m-2h-1and the rejections for all types of salts declined to under 11%. The above results indicated that SiO2-PSS incorporated into PES matrix played an important role in enhancing the performance of NF membranes, which may possess a significant impact on the application in dye purification and desalination.