Optimizing the spinning parameter of titania nanotube-boron incorporated PVDF dual-layered hollow fiber membrane for synthetic AT-POME treatment

Abstract

Dual layer hollow fiber membrane (DLHFM) offers the flexibility to independently tailor the outer and inner surface of hollow fiber membrane in a single step. The optimization of key spinning parameters is crucial to attain the desired membrane properties to suit its application. In this study, polyvinylidene fluoride (PVDF) DLHFM incorporated with titania nanotube-boron (TNT-B) in the outer layer was developed via dry/wet spinning using a triple orifice spinneret. As-synthesized TNT-B served as a promising nanofiller to improve the hydrophilicity, flux and rejection of DLHFM. Bore fluid flow rate (BFFR), outer layer dope solution flow rate (OLFR), air gap (AG) and nanofiller loading during the DLHF spinning were optimized through experimental approach. The resultant membranes exhibited triple layered sandwich structure, with a dense interlayer in the middle between a long finger like asymmetrical structure in its inner layer and a thinner finger like structure underneath the selective layer on the outer layer of membrane. The separation performances for bovine serum albumin (BSA), lignin and tannic acid (TA) of prepared membranes were evaluated. DLHFM spun with BFFR of 3 ml/min, OLFR of 3 ml/min, AG of 10 cm and nanofiller loading of 2 wt% exhibited the optimal performance by achieving pure water, BSA, lignin and TA flux of 97.65 L/m2h, 106.78 L/m2h, 37.48 L/m2h, 25.46 L/m2h and rejection of 99.12 %, 99.06 % and 78.51 %, respectively.