Abstract:
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.
