Abstract
This work investigates the effect of various membrane substrates and coating conditions on the formation of carbon/ceramic mixed matrix membranes for desalination application. The substrates were impregnated with phenolic resin via a vacuum-assisted method followed by carbonization under an inert gas. Substrates with pore sizes of 100 nm required a single impregnation step only, where short vacuum times (<120 s) resulted in low quality membranes with defects. For vacuum times of ≥120 s, high quality membranes with homogeneous impregnation were prepared leading to high salt rejection (>90%) and high water fluxes (up to 25 L m−2 h−1). The increase in water flux as a function of the vacuum time confirms the vacuum etching effect resulting from the vacuum-assisted method. Substrates with pore sizes of 140 nm required two impregnation steps. These pores were too large for the ceramic inter-particle space to be filled with phenolic resin via a single step. In the second impregnation step, increasing the concentration of the phenolic resin resulted in membranes with lower water fluxes. These results indicate that thicker films were formed by increasing the phenolic resin concentration. In the case of substrates with pores of 600 nm, these pores were too large and inter-particle space filling with phenolic resin was not attained.
Highlights
Access to water is one of the major problems facing many regions of the world, known as water poverty areas [1]
Phenolic resin is a carbon precursor of interest for the preparation of high quality carbon membranes [52–54] or as composite alumina carbon membranes [55–58] after pyrolysis. All these carbon membranes were prepared as films for gas separation, and generally display low water fluxes in pervaporation due to ultra-micropore sizes
As the vacuum-assisted method involves the impregnation of phenolic resin within the substrate structure, it warrants a detailed understanding of the role played by the substrate in the formation of carbon alumina mixed matrix membranes
Summary
Access to water is one of the major problems facing many regions of the world, known as water poverty areas [1]. Improved water fluxes have been achieved by preparing interlayer-free silica derived membranes, which have a lower resistance to water mass transfer than comparable membranes containing interlayers. All these methods have delivered structural variations such as changes in pore size and porosity. Elma and co-workers [35] reported that the water fluxes of carbonized template silica membranes were less affected by changes in feed salt concentration than pure silica This was attributed to the carbon structure repelling hydrated ions, contrary to silica that adsorbs hydrated salt ions [44] and adds extra resistance to water transport. Zeolite based membranes have shown major improvement in water fluxes from 0.2 to
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
