Preparation And Performance Evaluation Of Microwave - Assisted Ultrafiltration Membrane

Ultrafiltration, as a kind of efficient separation methods, was more and more used in oily wastewater treatment. The ultrafiltration has its unique advantages, but there are still some problems in the oil/water separation. Among them, the biggest problem is how to effectively prevent the ultrafiltration membrane of pollution, and decrease the cost of the ultrafiltration process. The purpose of this paper is to solve in pollution problems of ultrafiltration membranes in the separation of oily wastewater, based on the process of preparing ultrafiltration membrane casting membrane system to explore, develop a series of effective methods and membrane modules to separate oily wastewater.Compared with traditional heating method, microwave works mainly through dipole polarization and ionic conduction effect. The great advantages of microwave-heating are ephemeral, uniformity and efficiency and selectivity. With polyether sulfone (PES) being used to be the main body of membrane, polyoxyethylene (PEO) was employed as the hydrophilic modification to improve the hydrophilicity of ultrafiltration membrane, again with dimethyl formamide (DMF) as solvent. Considering the ionic conduction effect of microwave heating, anhydrous LiCl was employed in the casting membrane system. Because LiCl is well dissolved in the solvent of DMF, it can be spread very well with ion state in the dope.In this paper, the casting dope dissolve completely under the temperature of90℃, needs2hours with conventional heating, while takes30minutes to one hour with microwave heating. At the same time, under certain condition (LiCl:0.5%, microwave power110w), compared with conventional heating, the water flux incease from78.78L·m-2·h-1to169.50L·m-2·h-1(115.15%), contact angle dropped from90.45°to88.20°.Based on the field emission scanning electron microscopy (SEM), attenuated total reflection infrared (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) as the main means of characterization, the mechanism of microwave field are analyzed:due to the particularity of microwave heating, there is no temperature gradient inside the heated object, PES and PEO in DMF solution velocity greatly increased. Due to the ionic conduction effect of microwave, LiCl was dispersed in the casting dope better and faster. Because the different molecular polarity, the distribution of different components is different under the microwave field.