Study On Ce-doped Nonstoichiometric Nanosilica/PSF Composite Membrane And Its Property

Oily wastewater is a common pollution in the world which has lots of harm to environments, whereas water is important source of living and production. Thus, separation of oily wastewater is very important. Traditional treatment for oil/water separation had low efficiency or consumed lots of energy. In recent years, membrane technologies have been successfully applied for treating oil/waste emulsion which could supply a gap of those traditional treatments. However, the performances of membrane separation are limited by the membrane fouling and concentration polarization. Therefore, development of antifouling membranes is a most pressing task at present.According to membrane materials being essential of the membrane technology, this paper manages to prepare a new organic-inorganic polysulfone composite membrane filled with high activity and better hydrophilic nanosilica, which was synthesized by doping rare element cerium. The modification condition of high hydrophilicity was confirmed, which was as follow, the PSF concentration was 16wt. %, the concentrations of PEG400 and nanosilica were both 10% of PSF, the evaporating time was 10s, the coagulation bath temperature was 20℃, and the ultrasound was a batch operation.The intensity and hydrophilic property of modified membrane were heightened according to the result of mechanical strength and hydrophilic angle experiments. The SEM showed that the composite membrane had two layers which were composed of compact layer and porous layer, and the nanoparticles uniformly dispersed. Mass hydroxyl groups existed on the surface of composite membrane by refection FTIR and XRD. So the physical performance, hydrophilicity, separability and antifouling capability were improved much after modification.Oily wastewater, which the concentration was 65mg/L, was treated by composite membrane. During this process, the effect of composite membrane with different concentration of nanosilica to separation and antifouling capability was observed. The result indicated that the property of composite membrane with 10% nanosilica was best and it acquired the highest rejection ratio of 98.89% while the oil concentration of efflux was 0.72mg/L, reaching the water letting standard. And the water flux of used composite membrane after six time washing reached about 85% of initializing condition.This paper also discussed the antifouling mechanism of the composite membrane. Also the influence of membrane structure and the advantage to mass transfer in the inner membrane after filled with nanosilica were deep analyzed.