Improvement of Membrane Distillation Using PVDF Membrane Incorporated with TiO(2) Modified by Silane and Optimization of Fabricating Conditions

The objectives in this study are to improve the performance of PVDF membrane by incorporating TiO(2) and silane at various dosages and optimize fabricating conditions by using response surface methodology (RSM) for membrane distillation (MD) application. The PVDF membrane was synthesized by phase inversion method using various TiO(2), silane and polymer concentrations. Membranes were characterized by performing contact angle measurements, SEM and FTIR observations. Ammonia rejection and permeate flux were measured by operating a direct contact distillation module treating ammonium chloride solution. A PVDF membrane created by adding TiO(2) modified by silane improved membrane hydrophobicity. However, the effect of silane on membrane hydrophobicity was less pronounced at higher TiO(2) concentrations. Highest ammonium rejection was associated with the highest membrane hydrophobicity. RSM analysis showed that fabricating conditions to achieve highest flux (10.10 L/m(2)·h) and ammonium rejection (100.0%) could be obtained at 31.3% silane, 2.50% TiO(2), and 15.48% polymer concentrations. With a PVDF-TiO(2) composite membrane for MD application, the effect of TiO(2) was dependent upon silane concentration. Increasing silane concentration improved membrane hydrophobicity and ammonium rejection. RSM analysis was found to bea useful way to explore optimum fabricating conditions of membranes for the permeate flux and ammonium rejection in MD.