In this study, a carbon nanotube (CNT)-infused blended polymer membrane was prepared and evaluated for phenol and benzene removal from petroleum industry wastewater. A 25:75 (by weight %) blended polysulfone/polyethersulfone (PSF/PES) membrane infused with CNTs was prepared and tested. The effect of functionalization of the CNTs on the quality and performance of the membrane was also investigated. The membranes were loaded with CNTs at different loadings: 0.5 wt. %, 1 wt. %, 1.5 wt. % pure CNTs (pCNTs) and 1 wt. % functionalized CNTs (fCNTs), to gain an insight into the effect of the amount of CNT on the quality and performance of the membranes. Physicochemical properties of the as-prepared membranes were obtained using scanning electron microscopy (SEM) for morphology, Raman spectroscopy for purity of the CNTs, Fourier transform infrared (FTIR) for surface chemistry, thermogravimetric analysis (TGA) for thermal stability, atomic force microscopy (AFM) for surface nature and nano-tensile analysis for the mechanical strength of the membranes. The performance of the membrane was tested with synthetic wastewater containing 20 ppm of phenol and 20 ppm of benzene using a dead-end filtration cell at a pressure ranging from 100 to 300 kPa. The results show that embedding CNTs in the blended polymer (PSF/PES) increased both the porosity and water absorption capacity of the membranes, thereby resulting in enhanced water flux up to 309 L/m2h for 1.5 wt. % pCNTs and 326 L/m2h for 1 wt. % functionalized CNT-loaded membrane. Infusing the polysulfone/polyethersulfone (PSF/PES) membrane with CNTs enhanced the thermal stability and mechanical strength. Results from AFM indicate enhanced hydrophilicity of the membranes, translating in the enhancement of anti-fouling properties of the membranes. However, the % rejection of membranes with CNTs decreased with an increase in pCNTs concentration and pressure, while it increased the membrane with fCNTs. The % rejection of benzene in the pCNTs membrane decreased with 13.5% and 7.55% in fCNT membrane while phenol decreased with 55.6% in pCNT membrane and 42.9% in the FCNT membrane. This can be attributed to poor CNT dispersion resulting in increased pore sizes observed when CNT concentration increases. Optimization of membrane synthesis might be required to enhance the separation performance of the membranes.

Environmental sustainability requires development of environmentally benign and energy efficient technology for treatment and disposal of wastewater. Membrane technology has emerged as a highly viable method for water treatment throughout the years. However, their limited commercial application has prompted a lot of researchers to explore different approaches to modify the membranes to enhance their performance. Polymer blending is one of the modifying techniques currently being explored to develop materials with unique anticipated properties depending on the type of membrane needed. This technique has shown improvement in the quality of the membrane by enhancing the mechanical strength as well as the performance of the membrane. In this study, blended polysulfone (PSF) and polyethersulfone (PES) membranes were synthesized at different PSF:PES ratios (100%:0%, 0%:100%, 50%:50%, 80%:20%, 20%:80% and 25%:75%) using N-Methyl-2-pyrrolidone (NMP) as a solvent via the phase inversion method. The quality and integrity of the membranes were checked via Scanning electron microscopy (for morphology); Thermogravimetric analysis (for thermal stability), Atomic force microscopy (for surface nature) and nanotensile measurement for mechanical strength. The flux, % rejection and porosity as the performance criteria of membranes showed a massive improvement in majority of the blended membranes than in pure PES and PSF membranes. AFM images indicated lower roughness in the pure PSF membrane as compared to the blended membranes. The tensile strength only improved on the 25%:75% membrane while the elasticity increased with an increase in PES concentration in the blended membranes. These results demonstrate the diversity of blending polymeric membranes to modify specific properties for desired function and highlight the possibility of more commercial application.