Study on Ce-doped Nonstoichiometric Nano-silica/PSF Composite Membrane for Separation of Chinese Yam Polysaccharide

Abstract

In order to enhance the anti-fouling ability and separation efficiency of polysulfone (PSF) membrane during separating of Chinese yam polysaccharides, a novel composite membrane was prepared through a sol-gel process after adding Ce-doped nonstoichiometric nano-silica with higher activity and hydrophilic property to the porous matrix of PSF. Ce-doped nonstoichiometric nano-silica was synthesized by doping the rare earth Ce element. Novel composite membranes and ordinary membranes without doping Ce-doped nonstoichiometric nanosilica were used to separate Chinese yam polysaccharides while the content of polysaccharide was tested. The results designate that the content of polysaccharide separated by composite membrane which reached 78.3% was higher than that of polysaccharide separated by ordinary membrane which reached 46.7%. The flux of the composite membrane increased with increasing of operation pressure. With the temperature rising, the polysaccharide solution flux of composite membrane ascended from 289 L/(m2h) to 312 L/(m2h). The flux of the composite membrane was kept at a high value for 25 h before reaching a steady state (243 L/(m2h)), which was higher than the stable flux of ordinary membrane (160 L/(m2h)). After the composite membrane was washed for six times, its flux still reached 90% of initial value. The experiment data indicate that the anti-fouling ability and hydrophilic property of composite membrane were significantly enhanced. Therefore, Chinese yam polysaccharides can be efficiently separated by the novel composite membrane.