An overview of superhydrophobic ceramic membrane surface modification for oil-water separation

The discharge of oily wastewater and offshore oil spills contaminates the biotic and aquatic environment and ultimately result in the destruction of the ecosystem. Recently, the application of ceramic membranes has gained prodigious attention due to its efficiency in oil-water separation process. Ceramic membranes developed from inorganic materials are considered as the most promising technology for the treatment of industrial wastewater. Besides, different types superhydrophobic-superoleophilic substrates are being developed using various substrate materials to tailor its purpose for higher efficiency. Nonetheless, fouling and clogging phenomena restrict the performance of ceramic membrane in oil-water separation. This review emphasizes the recent innovation on superhydrophobic methods for the modification of ceramic membranes for oil-water recovery. It comprises of an overview of the preparation technique of ceramic membrane using various techniques. Moreover, the different types of hydrophobic ceramic membrane modification using chemical agents and consequent effects on oil-water separation were discussed in detail. Furthermore, the technical challenges and issues associated with the applications of superhydrophobic-superoleophilic ceramic membrane for oil-water separation were discussed. Finally, future direction in the research of cost-efficient approach to produce superhydrophobic ceramic membranes for oil-water filtration process is enumerated

Facile approach in development of superhydrophobic-superoleophilic kaolin-based hollow fibre ceramic membrane

A silane coupling agent is an organosilicon compound with special structure possessing organic functional groups and hydrolysable groups. In this study, a superhydrophobic-superoleophilic nano-silica film on ceramic membrane was constructed by a modified Stöbertechnique by using tetraethoxy-silane (TEOS) and fluoroalkyl silane (FAS). The colloidal nano-silica based silane sol coating solution was synthesized via co-hydrolysis and co-condensation of TEOS and FAS. Particle size distribution of the colloidal nano-silica based silane sol was evaluated using particle size analyzer as depicted. The contents of the relative elements of the colloidal nano-silica based silane sol were examined using energy dispersive x-ray (EDX) spectra. Extent of superhydrophobicity-superoleophilicity was determined using the contact angle measurements. The surface wettability of superhydrophobicity-superoleophilicity was determined using the contact angle measurements. Also, the effects of grafting times and coating cycles on the wettability of the modified kaolin-based hollow fiber membrane were determined. The results revealed that the modified kaolin-based hollow fiber membrane exhibited oil contact of 0o and water contact angle of 160o and, demonstrating its considerable antiwetting applications like in oil-water filtration process. While, with an increase in grafting times and coating cycles, the wettability of the superhydrophobic-superoleophilic nano-silica film was enhanced due to increase in surface roughness provided by the hydrolysable groups on the surface of the ceramic membrane. In conclusion, this study presents a feasible route to the surface superhydrophobicity-superoleophilicity testing of ceramic membrane

Recent development in modification of polysulfone membrane for water treatment application

Polysulfone (PSF) membranes have been widely used for wastewater treatment due to their desired properties like stability, high mechanical strength and ease of modification. The modification of PSF membranes presents a great opportunity in improving their performance in the field of wastewater treatment. This review presents a comprehensive review of PSF ultrafiltration (UF) and microfiltration (MF) membranes modification via various techniques as well as novel modifiers for water purification by paying attention to various issues inherent in the modification process. Recent studies on nanomaterial as well as hydrophilic macromolecules used for the modifications of PSF UF/MF membranes for water treatment application have been comprehensively analysed. These modified membranes exhibited a remarkable improvement with regards to water permeability, salt rejection and anti-fouling features of PSF modified membranes when compared to the neat PSF membranes. The modification techniques such as coating, grafting/blending, layer by layer and deposition are discussed. Besides, the impacts of these modifiers on the performance of the membranes for wastewater treatment as well as their environmental impacts are discussed. Based on the literature review, it is obvious that nanomaterial/hydrophilic macromolecules modified PSF membranes have unique features that can contribute to the advancement of innovative nanocomposite membranes with enhanced capacities for wastewater treatment