Pervaporation Separation Of Ethylene Glycol And Water Mixtures Through Modified Chitosan Membranes

Pervaporation, as a novel liquid mixture separation technology, has outstanding technical advantages and favorable promising application prospects in the dehydration of organic aqueous solutions. Separation performance of pervaporation process mainly depends on the property of the target membranes, therefore selecting the appropriative material with excellent separation performance constitutes an important issue in pervaporation research.In our work, chitosan (CS) and poly (acrylic acid) (PAAc) were chosen out as the membrane materials considering the solution parameters, hydrophilic/hydrophobic balance, chemical structures, properties difference of ethylene glycol and water. The polyelectrolyte complex membranes (PECM) composed of CS and PAAc were prepared by blending two polymer solutions with different ratios. Also mordenite filled polyelectrolyte complex membranes (PECM) were prepared for dehydration of ethylene glycol.The structure morphology, the physical and chemical properties of the membranes were characterized and analysed by FT-IR, XRD, SEM, TGA and universal testing machine. The relationships between properties of membrane material and separation performance of the membrane were discussed.The separation performance of CS/PAAc polyelectrolyte complex membranes and mordenite filled polyelectrolyte complex membranes for dehydration of ethylene glycol aqueous solution was investigated. The effects of PAAc content and mordenite content on the pervaporation performance and swelling behaviour were discussed. Moreover, effects of operating conditions (EG concentration in feed, feed temperature, feed flow rate) on pervaporation performance and swelling behavior were also studied. From the results, PECM60/40 containing 40wt% PAAc exhibited the separation performance with a permeation flux of 216g/(m2h) and a separation factor of 105 at 70oC for 80wt% EG aqueous solution, keeping feed flow rate 100L/h, downstream pressure at about 0.67kPa. After filling mordenite, the separation performance of the membranes was improved indicated by the remarkably increased separation factor and the slightly decreased permeation flux. The filled membrane containing 4wt% mordenite showed the highest separation factor of 258 with a permeation flux of 165g/m2h for 80wt% EG in feed at 70oC.