Hydrophobic capillary membrane based on clay-alumina formulation for membrane distillation process

摘要

Membrane Distillation (MD) processes are based on commercially available polymeric hydrophobic membrane. Polymeric hydrophobic membrane has some disadvantages owing to the intrinsic properties of polymer material when compared to the ceramic membrane like high temperature, pressure and chemical sensitivity, low mechanical strength etc. Ceramic membranes on the other hand are expensive than polymeric membrane and are generally hydrophilic in nature with high membrane thickness which increases the membrane resistance altogether making it not suitable candidate for MD process. In the present work a low cost capillary membrane has been prepared based on clay-alumina formulation fired at 1450°C to obtain a pore size of 1 micron (approx) and porosity of 40% (approx). With capillary configuration the membrane resistance was minimized by reducing the wall thickness to as low as 500 micron. Surface of the ceramic capillary was coated with gama alumina sol to prepare ultra filtration membrane with 10 nm (approx) Pore size. The surface of macro porous uncoated capillary and the nano porous membrane layer of the coated capillary have been modified to impart hydrophobic characteristics by chemically grafting with fluoroalkylsilanes (FAS) over them. Thus a low cost ceramic hydrophobic capillary membrane has been prepared with a combination of required qualities from both the polymeric and ceramic materials with different pore size. These membrane are characterized based on the contact angle, liquid entry pressure (LEP), chemical stability etc and compared.