Optimization of TiO2 modified poly(vinyl alcohol) thin film composite nanofiltration membranes using Taguchi method

In this study the L16 orthogonal array of the Taguchi method has been applied to determine the optimum condition of three controlling factors i.e. PVA, gluteraldehyde and TiO2 nanoparticle concentration for preparing PVA/PES composite membrane. PES ultrafiltration membrane was prepared via immersion precipitation technique and subsequently was used as support layer. Different PVA/PES composite membranes were fabricated at various PVA concentrations, glutaraldehyde concentration as the cross-linking agent and nano-sized TiO2 as membrane surface and performance modifier. The membranes were characterized in terms of morphology, surface properties and filtration performance via SEM, AFM, XRD, contact angle and cross flow filtration. Filtration tests were done on yeast industrial wastewater with COD level of 11,500 mg/l. Taguchi approach was employed to determine the optimum condition and achieve the best permeate flux and COD removal. As two series of data were examined, two optimized membranes were obtained from permeate flux and COD level points of view. According to the surface analysis, TiO2 nanoparticles were successfully coated on the surface of both optimized membranes. The comparison between two optimized membranes showed that the membrane optimized from COD level point of view had an efficiency of about 98% while the membrane optimized from permeate flux point of view had about 97% output. The long-term flux measurements indicated that the permeate flux of the membrane optimized from flux point of view was approximately 8 l/m2·h while for the membrane optimized from COD point of view was about 2.5 l/m2·h. Therefore, the membrane optimized from permeate flux point of view was more beneficial and affordable.

► PES/PVA composite nanofiltration membrane was modified using TiO2 nanoparticles.
► The optimum condition for preparing PVA/PES membrane was determined by Taguchi method.
► Two optimized membranes were obtained from permeate flux and COD level points of view.