Study on the fouling behavior of silica nanocomposite modified polypropylene membrane in purification of collagen protein

In this study, microporous polypropylene (PP) membrane was fabricated via thermally induced phase separation (TIPS) method. Using Stober method, hydrophilic SiO2 nanoparticles (NPs) were synthesized by in situ and ex situ approaches and covalently connected to the membrane via hydrolysis-condensation reactions with hydroxyl (-OH) groups, created by Piranha solution (3:1, v/v, H2SO4 and H2O2) in pretreatment step. The average sizes of SiO2 NPs synthesized by in situ and ex situ approaches were about 250-300nm and 15-20 nm, respectively. Incorporation of SiO2 NPs on the membrane surface improved surface hydrophilicity, pure water flux and mechanical properties and increased the portion of reversible fouling ratio (RFR) which consequently resulted in higher flux recovery (FR) of the membrane due to the hydrophilic property of SiO2 NPs. The flux recovery (FR) increased from 64.5% for unmodified membrane to 71.8%, 79.2% and 88.6% for PP-SiO2 composite membranes prepared by in situ and two ex situ routes with 6 and 12 h immersion time intervals, respectively. Application of combined fouling models revealed that the "cake filtration-standard blockage" fouling mechanism is prevailing fouling mechanism for all membranes. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.