Hydrophobic Ceramic Membranes for Water Desalination

Abstract

Hydrophilic ceramic membranes (tubular and planar) made of TiO 2 and Al 2 O 3 were efficiently modified with non-fluorinated hydrophobic grafting molecules. As a result of condensation reaction between hydroxyl groups on the membrane and reactive groups of modifiers, the hydrophobic surfaces were obtained. Ceramic materials were chemically modified using three various non-fluorinated grafting agents. In the present work, the influence of grafting time and type of grafting molecule on the modification efficiency was evaluated. The changes of physicochemical properties of obtained hydrophobic surfaces were determined by measuring the contact angle (CA), roughness (RMS), and surface free energy (SFE). The modified surfaces were characterized by contact angle in the range of 111-132 • . Moreover, hydrophobic tubular membranes were utilized in air-gap membrane distillation to desalination of sodium chloride aqueous solutions. The observed permeate fluxes were in the range of 0.7-4.8 kg·m −2 ·h −1 for tests with pure water. The values of permeate fluxes for membranes in contact with NaCl solutions were smaller, within the range of 0.4-2.8 kg·m −2 ·h −1 . The retention of NaCl in AGMD process using hydrophobized ceramic membranes was close to unity for all investigated membranes.

Ceramic membranes applied to membrane distillation: A comprehensive review

“…The publications of ceramic membranes applied to MD analyzed LEP using water and values ranging from 0.5 to 16 bar were obtained. Some authors reported that smaller values of LEP led to higher permeate flux . Nevertheless, even that LEP is an important characteristic for membranes applied to MD, about 40% of the current publications did not report its value, probably due to the fact of an additional apparatus for LEP measurement.…”

“…Searches in the literature show that about 95% of the publications used grafting for surface modification of ceramic membranes, whereas only 5% used texturing. The creation of a rough surface, that is, generation of heterogeneity on the surface, is possible to form highly hydrophobic surfaces due to the generation of pillars and the presence of air pockets on the surface . Two studies reported the use of a framework of MFI zeolites as hydrophobic surface modification .…”

“…These molecules are attached by covalent bonds to the hydrophilic, pristine surface rich in hydroxyl groups, creating a hydrophobic layer on the ceramic surface (Figure ). The effect of different grafting agents in the same ceramic membrane is reported in the literature . The most used grafting agents are 1H,1H,2H,2H‐perfluorodecyltriethoxysilane and 1H,1H,2H,2H‐perfluorooctyltriethoxysilane.…”

Keramische Membranen in der Membrandestillation

“…Keramische Membranen wurden bereits erfolgreich in ihren Oberflächeneigenschaften modifiziert und in der MD getestet . Um die Leistungsfähigkeit keramischer Membranen in der MD darüber hinaus beschreiben und Optimierungspotenziale identifizieren zu können, sind weitere Untersuchungen notwendig.…”

Preparation of high-efficiency ceramic planar membrane and its application for water desalination

“…Compared to polymeric membranes, ceramic membranes can withstand harsh environments due to their excellent mechanical strength, chemical stability, and thermal resistance [10][11][12]. Many researches have been reported to explore ceramic membrane application in MD [13][14][15][16]. Recently, inorganic modifiers were used for ceramic membrane modification to achieve hydrophobic structure.…”