ORIGINAL PAPER Influence of TiO 2 nanoparticles loading on permeability and antifouling properties of nanocomposite polymeric membranes: experimental and statistical analysis Mohammad Enayatzadeh 1 & Toraj Mohammadi 1 & Narges Fallah 2 Received: 22 February 2019 /Accepted: 17 August 2019 # The Polymer Society, Taipei 2019 Abstract Influence of the dope solution concentration on final membrane properties, regarding TiO 2 role, was investigated. For this purpose, blended flat sheet poly(vinylidene fluoride) (PVDF)-based membranes with different proportions of poly(vinyl pyrrolidone) (PVP)/ TiO 2 ratios were prepared via phase inversion process. The final application of the membranes was evaluated, especially in contact with vital microbial mixed liquor, in membrane bioreactors due to antibacterial properties of TiO 2 and environmentally concern of nanoparticles application. Response surface methodology (RSM) was used as a precise and multivariate technique to estimate and navigate the system performance at any experimental point within the investigation domain. Filtration properties, flux recovery ratio and (Protein flux / pure water flux: Jp/Jw) ratio of the membranes were investigated statistically to propose the formulations for the optimal performance. The correlation showed good agreement with the measured pure water flux and flux recovery ratio values of the fabricated membranes, with R 2 values higher than 90%. The findings are significant since demonstrating that the loaded nano TiO 2 particles around 0.5 wt% improve pure water flux, however, based on the Pareto analysis, experimental values and environ- mental safety concern, nanoparticles loading can be neglected in comparison with the other factors investigated in this study. Keywords TiO 2 nanoparticles . Polymeric membranes . Hydrophilic modification . Response surface methodology Introduction According to the world population growth and industrial activi- ties in the world, wastewater production has been reported as one of the significant problems in the last decades. Many technolo- gies have been applied to municipal and industrial wastewater treatment. Nowadays, the membrane separation process is one of the considerable technologies [1]. In this field, membranes play a crucial role in water treatment processes such as membrane bioreactors (MBRs) [1–3] and can determine the efficiency and economic aspects of the aforementioned treatment. Based on different applications, different materials [4], fabrication tech- niques, membrane configurations, etc. are applied [1, 5–9]. Among various polymeric materials, PVDF which consists of (-CH 2 -CF 2 -), is one of the most frequently used material in microfiltration (MF) and ultrafiltration (UF) processes due to its excellent thermal stability and chemical resistance to acids, basis and organic solvents [4]. In most cases, PVDF flat sheet membranes are obtained simply via the immersion precipita- tion (IP) method. In the IP technique, different types of mor- phology, pore size and porosity of the membrane can be achieved depending on the IP process conditions such as rel- ative diffusion rate of solvent, and non-solvent, bath temper- ature and composition, casting temperature, humidity and many other factors [6, 10]. The ultimate PVDF membranes fabricated using this method show good tensile strength and proper asymmetric structure for separation [3, 5, 6, 8, 11–22]. However, in the MBR systems, neat PVDF membranes are incredibly prone to fouling by microorganisms and other wastewater components due to hydrophobic nature of PVDF which mainly leads to a sharp water flux decline [5]. * Toraj Mohammadi torajmohammadi@iust.ac.ir Mohammad Enayatzadeh enayatzadeh@gmail.com Narges Fallah nfallah2001@aut.ac.ir 1 Research Centre for Membrane Separation processes, Faculty of Chemical, Petroleum and Gas Engineering, Iran University of Science and Technology, Tehran, Iran 2 Faculty of Chemical Engineering, Amirkabir University of Technology, Tehran, Iran Journal of Polymer Research (2019) 26:240 https://doi.org/10.1007/s10965-019-1892-4