Enhancement of antifouling properties using rice husk silica particles in polysulfone membrane and optimization of its operating condition

This study investigates the effects of rice husk silica (RHS) as additive in the polysulfone membrane to enhance antifouling properties in membrane separation process. The flat sheet PSf/RHS membrane was prepared via phase inversion technique. The characterization and performance test were conducted on PSf ultrafiltration membrane prepared from a different additive concentration. The thermal stability of prepared membrane was observed by using thermogravimetric analysis (TGA). The cross section area and particles distribution of additive were carried out by using the scanning electron microscope (SEM) while the surface morphology was investigated via field emission scanning electron microscope (FESEM). The surface roughness and hydrophilicity were also determined by using Atomic force microscopy (AFM) and contact angle measurement respectively. Meanwhile, the performance was evaluated in term of pure water flux (PWF), rejection and antifouling properties. The optimized of normalized flux (Jf /Jo) at different parameter filtration condition (pH, ionic strength and tranmembranepressure) was carried out by using the response surface methodology (RSM). From the analysis of SEM, FESEM and AFM, results showed that the microstructure of the membrane especially at top layer and sub layer obviously changed with the incorporation of RHS. The results also demonstrated that the mean pore size was decreased and hyrophilicity was increased as increased RHS particles in PSf membrane. The performance of the membrane was analyzed by using distilled water for permeation test and humic acid for the rejection test. The results also showed that the hydrophilic PSf/RHS membrane has significantly improved the permeation and rejection performance after the addition of RHS. The results showed that the addition of 4 wt. % RHS give the highest flux at 300.50 L/m².hour (LMH). The highest rejection was found at 3 wt. % of RHS membrane with value 98% for UV254 and 96% for TOC. The optimal value of Jf/Jo was found at 0.62 with the parameter condition pH: 6.10, ionic strength: 0.05 mol/L and transmembrane-pressure: 2.67 bars. Optimize of RSM analysis also proved that the error of model is less than 0.05% which indicates that the model is significant