No abstract

No abstract

No abstract

The objectives in this study are to improve the performance of PVDF membrane by incorporating TiO2 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 TiO2, 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 TiO2 modified by silane improved membrane hydrophobicity. However, the effect of silane on membrane hydrophobicity was less pronounced at higher TiO2 concentrations. Highest ammonium rejection was associated with the highest membrane hydrophobicity. RSM analysis showed that fabricating conditions to achieve highest flux (10.10 L/m2·h) and ammonium rejection (100.0%) could be obtained at 31.3% silane, 2.50% TiO2, and 15.48% polymer concentrations. With a PVDF-TiO2 composite membrane for MD application, the effect of TiO2 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.

This study aims to investigate the effect of operational conditions on organic fouling occurring in a direct contact membrane distillation (DCMD) system used to treat wastewater. A mixed solution of sodium alginate (SA) and bovine serum albumin (BSA) was used as a feed solution to simulate polysaccharides and proteins, respectively, assumed as the main organic foulants. The permeate flux was observed at two feed temperatures 35 and 50 °C, as well as three feed solution pH 4, 6, and 8. Higher permeate flux was observed for higher feed temperature, which allows higher vapor pressure. At higher pH, a smaller particle size was detected with lower permeate flux. A mathematical model based on mass balance was developed to simulate permeate flux with time by assuming (i) the cake formation controlled by attachment and detachment of foulant materials and (ii) the increase in specific cake resistance, the function of the cake porosity, as the main mechanisms controlling membrane fouling to investigate the fouling mechanism responsible of permeate flux decline. The model fitted well with the experimental data with R2 superior to 0.9. High specific cake resistance fostered by small particle size would be responsible for the low permeate flux observed at pH 8.

No abstract