In this work, the flexibility of polycarbonate (PC) membrane was improved by using polyurethane (PU) additive. However, due to the hydrophobic nature of the PU polymer, alumina (Al2O3) nanoparticles were incorporated to PC‐PU blend membrane. The prepared membranes have been used in a submerged membrane system to eliminate humic acid molecules from polluted water in both the presence and absence of coagulant (polyaluminum chloride). The obtained results showed that introduction of PU into PC membrane diminished hydrophilicity and enhanced porosity. Moreover, the flexibility of the PC membrane remarkably improved. Introduction of 1.5 wt% Al2O3 to the PC‐PU blend membrane led to enhancement in both porosity and hydrophilicity. Results of morphological studies showed that in the presence of Al2O3 nanostructures, finger‐shaped voids seemed to elongate across the entire thickness of the prepared membrane. Atomic force microscopy images showed that incorporation of PU and Al2O3 to the PC membrane resulted in a smoother surface. The antifouling performance of membranes revealed that the PC‐PU/Al2O3 nanocomposite membrane possessed the most favorable antifouling features owing to its lowest surface roughness as well as highest hydrophilicity. For all membranes utilizing coagulant (PAC), the irreversible fouling ratio and the flux recovery ratio significantly diminished and increased, respectively.
In this study, nanocomposite membranes based on cellulose acetate (CA) and nanodiamond (ND) were prepared by applying phase inversion methods. In order to achieve efficient dispersion and more hydrophilic NDs, they were functionalized via heat treatment (ND-COOH). The prepared nanocomposite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle, porosity measurement, tensile strength, and abrasion resistance techniques. Furthermore, the governing fouling mechanisms were determined by using classic models as well as combined fouling models. Moreover, the effect of precoagulation with polyaluminum chloride (PAC) on the humic acid (HA) filtration was investigated. The obtained results showed that in the presence of ND-COOH, the abrasion resistance of nanocomposite CA membrane was three times higher than that of pristine CA membrane. Besides, the nanocomposite membranes with 0.5 wt % of raw and functionalized ND exhibited excellent hydrophilicity and PWF. The analysis of fouling mechanism based on Hermia's model revealed that the cake formation is prevailing mechanism for CA and CA/ND (0.5 wt %) membranes while for CA/ND-COOH (0.5 wt %) membrane, experimental results are fitted by combined cake filtration-complete blocking (CFCB) model. It confirms that pretreatment with PAC can significantly mitigate fouling and improve HA removal.
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