Three different molecular weights of quaternary ammonium salts of chitosan （CTS-QTS） were prepared by ultrasonic degradation. The degraded products were characterized by Fourier transform infrared spectroscopy （FT-IR） and gel permeation chromatography （GPC）. Different relative molecular mass and different contents of CTS-QTS solutions were studied as draw solutions. The physical properties, such as viscosity, conductivity and osmotic pressure were investigated. The changing rules of water flux, reverse solute flux, salt rejection rate in forward osmosis （FO） process under different content and different membrane orientations Were explored. The results showed that the water flux of AL-DS mode was higher than that of AL-FS mode and reverse solute flux of AL-DS mode was almost twice than that of AL-FS mode. The salt rejection rates were both over 99.9% in the two membrane orientations. Moreover, salt rejection rate of AL-FS mode was slightly higher than that of AL-DS mode. Water recovery rates of draw solutions also exhibited good performance under different content of CTS-QTS as draw agents. Therefore, CTS-QTS was potential to be a green and low-energy consumption of draw agent in forward osmosis.
Technology of Water Treatment
quaternary ammonium salt of chitosan