Development of hydrophobic clay–alumina based capillary membrane for desalination of brine by membrane distillation

Abstract

a b s t r a c tClay-alumina compositions of 0, 20, 40 and 55 weight percent (wt%) clay and rest alumina were maintained in porous support preparation by extrusion followed by sintering at 1300 • C for 2.5 h to obtain 3 mm/2 mm (outer diameter/inner diameter) capillary. 1H,1H,2H,2H-perfluorodecyltriethoxysilane (97%) (C8) was used to modify the capillary surface of all compositions without any intermediate membrane layer to impart hydrophobic characteristics and compared in terms of contact angle produced by the capillaries with water and liquid entry pressure (LEP w ). FTIR analysis showed that the hydrophilic surface of the capillary membranes was efficiently modified by the proposed grafting method. Capillary with 55 wt% clay produced a pore size of 1.43 micron and was considered as an ideal candidate for grafting with C8 polymer to impart surface hydrophobicity. The contact angle and LEP w value obtained for this modified membrane (C-55-M) were 145 • and 1 bar, respectively. The modified capillary membrane was applied for desalination of brine by air gap membrane distillation (AGMD) at a feed pressure of 0.85 bar. Maximum flux obtained for C-55-M membrane was 98.66 L/m 2 day at a temperature difference of 60 • C with salt rejection of 99.96%. Mass transfer coefficient of C-55-M was 16 × 10 −3 mm/s at feed temperature of 70 • C.

Ceramic membranes applied to membrane distillation: A comprehensive review

“…Recent publications have tended to focus on producing novel ceramic materials specifically to MD, rather than on commercial ceramic membranes. Some examples include kaolin [Al 2 Si 2 O 5 (OH) 4 ], silicon nitride with SiNCO nanoparticles (NPs), bi‐layered yttria‐stabilized zirconia (YSZ), β‐Sialon coated with polydimethylsiloxane (PDMS), alumina and clay (kaolin), alumina support and zeolite mordenite framework inverted (MFI), mud of hydrocyclone laundries of phosphates/zirconia, Tunisian clay, green silica‐based ceramic membrane derived from rice husk ash waste, and silicon dioxide‐coated silicon oxynitride . Each publication reported in detail the fabrication of the membrane.…”

“…One limitation of a ceramic membrane is the high thickness, which increases the mechanical stability but also increases mass transfer resistance . Membrane thickness requires an optimal value, which depends on solute concentration and process conditions .…”

“…Many authors reported that feed temperature showed a remarkable influence on the permeate flux with ceramic membranes applied to MD, regardless of configuration and feed solution. This propensity is explained by the Antoine equation, which predicts an exponential relationship between the vapor pressure difference and temperature due to the higher latent heat of water evaporation and higher heat transfer coefficient, without affecting the permeate quality.…”

“…This propensity is explained by the Antoine equation, which predicts an exponential relationship between the vapor pressure difference and temperature due to the higher latent heat of water evaporation and higher heat transfer coefficient, without affecting the permeate quality. Some publications proved experimentally that the permeate flux has a nonlinear relation with feed temperature, indicating the importance of the possible temperature polarization during the MD process …”

Ultrasonic-assisted removal of inorganic scales in high-salinity wastewater treatment using membrane distillation

“…Membrane distillation (MD) has become an important emerging water treatment technology and has the potential to replace conventional desalination techniques such as conventional desalination (MED, MSF) and reverse osmosis (RO) [1][2][3]. The MD has several advantages over conventional desalination technologies such as reverse osmosis (RO), multi-stage flash (MSF), multi effect distillation (MED), including low operating temperature and low hydraulic pressure, high salt rejection, and performance independent of high osmotic pressure for the feed water [1,[3][4][5][6][7][8][9][10][11][12][13][14]. For these reasons, MD is considered for various applications including sweater desalination to produce freshwater [1,3,[5][6][7][8]13,14].…”