Crosslinking Modification Of Poly (Vinyl Alcohol) (PVA) And Chitosan(CS) Membranes For Ethanol Dehydration Via Pervaporation

With the shortage of energy sources and more serious environmental deterioration,bioethanol as a new type of renewable energy, has drawn more and more global attentions.Separation process is a vital process in the bioethanol production. Pervaporation, a kind of membrane-based separation technique, has gained much attention as “clean technology”for the molecular-scale liquid separations in the past decades.Poly(vinyl alcohol)(PVA), is the most popular membrane material for pervaporation dehydration, because of its high hydrophilicity, excellent processability, and available hydroxyl groups for easy modification. However, PVA-based membranes generally lack mechanical strength and stability in the aqueous solution due to the excessive swelling phenomenon, thereby leading to a drastic decline in the separation performance. In order to solve the above problem, the crosslinking modification by anhydrides and siloxanes is employed in this work to achieve a higher separation performance and stability of the pervaporation membranes.Another common membrane material for pervaporation, chitosan(CS), as the only cationic natural polymer, has many advantages and available amino and hydroxyl groups for esay modification. However, the poor water resistance, low stability and weak toughness of CS-based membranes make it necessary to do further modification of CS membranes for pervaporation applications. Tetrakis(hydroxymethyl)phosphonium sulfate(THPS) is used in this work to surface crosslinking of CS membranes in order to improve the pervaporation performance and stability of CS membranes.