การดัดแปลงเมมเบรนพอลิซัลโฟนสำหรับการแยกแก๊ส CO2/CH4 โดยเทคนิคพลาสมากระแสตรง

Abstract

The aim of this work is to develope polysulfone membranes with high selectivity and permeability for separation of CO2 / CH, gas using Dry/Wet Phase Inversion technique. The effects of evaporation time of solvents in air, coagulation of bath temperature and concentration of ethanol in the polymer solution on the gas selectivity were studied. The result showed that the optimum condition for gas selectivity of CO2/CH, was the evaporation time, coagulation bath temperature and ethanol concentration added in casting solution of 120s, 10°C and 15.9%, respectirely. However, due to the inverse relationship of the selective value with the permeability, when the properties of the gas are increased, the gas permeability decreases. The membrane has been modified by irradiating with plasma in order to enhance the hydrophilic properties of the membrane surface. Due to its hydrophilic nature, CO, can be better than CH,, resulting in better permeability of CO, gas through the membrane. Therefore, the improvement of the membrane using the Dry/Wet Phase Inversion technique combined with the plasma technique can increase the selectivity through the permeability of the gas. But the hydrophilic property on the surface of the plasma-derived membrane is quickly dissipated. The retention of hydrophilic property of the plasma-derived membrane that modify by argon (Ar), oxygen (O2), mixed argon and oxygen (Ar & O2), sequences of argon and oxygen (Ar_O2) and sequences of oxygen and argon (O2 Ar) plasma have been studied. The plasma-derived membrane characteristic has been studied for wettability via Water Contact Angle (WCA) measurement while surface energy measurement using Fourier-Transform Infrared Spectroscopy (FTIR) and X-Ray Photoelectron Spectroscopy (XPS). The result show that modified membrane that bombarding with sequence of argon and oxygen plasma can enhance the hydrophilic property and can increase the permeability of CO/CH, up to 230% if compare with the untreated membrane. The hydrophilic property of plasma-derived membrane by sequence of argon and oxygen plasma has been prolonging up to 70 days.