以3种不同分子量的壳寡糖(COS)溶液为汲取液，研究了汲取液浓度与pH值、电导率、粘度和渗透压的关系，分析了不同分子量、壳寡糖浓度、膜活性层朝向时的水通量、反向溶质通量和截留率等因素的变化规律，讨论了其对纯水的回收率. 结果表明，壳寡糖溶液具有较高的电导率和渗透压，可产生较高的水通量，正渗透膜的活性层朝向汲取液(AL?DS)模式时的水通量优于活性层朝向原料液(AL?FS)模式，但AL?DS模式下的反向溶质通量较AL?FS模式大；两种模式下膜的截留率均在99.9%以上，且AL?FS模式的截留率略高于AL?DS；COS汲取液对纯水的回收性能良好.

Three different molecular weights of chitosan oligosaccharide (COS) were explored as draw agents in the forward osmosis (FO) process. The physical properties such as pH, conductivity, viscosity and osmotic pressure were investigated. The change regularity of water flux, reverse solute flux, rejection rate in the FO processes under different molecular weights, different concentrations and different membrane orientations were explored. Water recovery rates were also evaluated. The results showed that their characteristics of high conductivity and high osmotic pressure can provide favorable FO performance. The water flux of AL?DS mode is higher than that of AL?FS mode and reverse solute flux of AL?DS mode is also slightly higher than that of AL?FS mode. The rejection rates are both over 99.9% in the two membrane orientations. Moreover, rejection rate of AL?FS mode is slightly higher than that of AL?DS mode. Water recovery rates of draw solutions also exhibit good performance under different concentrations of COS as draw agents.Key words: forward osmosis; draw solution; chitosan oligosaccharide