A review on the manufacturing techniques of porous hydrophobic ceramic membranes applied to direct contact membrane distillation

Abstract

Porous hydrophobic ceramic membranes have been increasingly applied in advanced membrane-based separation processes such as Direct Contact Membrane Distillation (DCMD) due to their higher chemical and mechanical resistances. The development of novel ceramic membranes enhanced with porosity is based on conventional techniques such as extrusion and tape casting, and unique processing such as dry-wet spinning and vacuum filtration. The relationships between shaping and surface hydrophobization related to the membrane structure, properties and performance of the ceramic membrane applied to DCMD are explained in this work. The manufacturing technique influences the membrane characteristics, and consequently the permeability in DCMD. Recent research is focused on manufacturing high porous hollow fibre ceramic membranes by dry-wet spinning. In contrast to the grafting of alkylsilanes, the chemical vapour deposition process has been applied as an effective surface modifying technique to enhance membrane hydrophobicity. Ceramic membranes are mostly applied to desalination in DCMD and have been little researched concerning the unique properties they can offer, such as superhydrophobicity and use in a harsh environment. In addition to the review of manufacturing techniques, polymer-derived ceramic (PDC) is proposed as a one-step ceramic membrane processing route for DCMD. Although only a handful of works addressed the use of PDC membranes applied to DCMD, the great potential of these materials is forecast.

Eco-Friendly Superhydrophobic Modification of Low-Cost Multi-Layer Composite Mullite Base Tubular Ceramic Membrane for Water Desalination

“…MD is a separation technique that relies on the vapor pressure difference of volatile substances passing through the pores of a hydrophobic membrane [7]. The MD process is a unique combination of thermal and membrane techniques, where the liquid feed is transformed into vapor and conveyed through hydrophobic membrane pores [7,8]. In addition to wastewater treatment, the MD process can be employed to produce fresh water, remove heavy metals, recover salt from high-concentration aqueous solutions, address radioactive pollution, and facilitate the removal of produced ethanol in the food industry [8].…”

“…The MD process is a unique combination of thermal and membrane techniques, where the liquid feed is transformed into vapor and conveyed through hydrophobic membrane pores [7,8]. In addition to wastewater treatment, the MD process can be employed to produce fresh water, remove heavy metals, recover salt from high-concentration aqueous solutions, address radioactive pollution, and facilitate the removal of produced ethanol in the food industry [8]. The remarkable features of the MD process include high-purity products, compact volume, performance at low pressure (about 1 bar), low sensitivity to concentration polarization, and most importantly, distillation below boiling point (40-80 • C), which helps to reduce costs and energy consumption and also demonstrate a higher level of resistance to scaling in comparison to the RO process [9][10][11][12].…”

Approaches to Preceramic Polymer Fiber Fabrication and On-Demand Applications

“…Inorganic fibers are formed by pyrolysis of an organic template fiber, which is then soaked in preceramic precursor materials, or precursor materials are deposited on its surface. A direct process involves the direct spinning of inorganic precursors (solutions of salt, suns, or molten precursors) into "green fibers", sometimes using organic polymer additives [15][16][17][18][19][20].…”