Synthesis, characterization and application of Chitosan and its composite films

Abstract

Chitosan a natural carbohydrate biopolymer possesses unique properties that may be newlineenhanced by forming it as thin film or membrane structure. The chitosan films have newlineenormous surface area per unit volume (high aspect ratio), which provide remarkable newlinecapacity for attachment or release of functional groups, absorbed molecules, ions and particles of many kinds. The main objectives are to form chitosan membranes / films of various sizes in order to study the selective adsorption property of heavy metal ions present in leather tanning effluents, to study the structure property relationship between the host polymer and ion conducting species and to study the suitability of chitosan acid /salt systems to function as biopolymer electrolyte. Suitable moulds were prepared and various deposition parameters were optimized for the formation of flexible free standing films. The pure chitosan films were porous natured with the porosity of 88% and it selectively adsorb Cr-VI from tannery effluent. Various spectroscopic methods were newlineadopted to characterize the interaction of solvent with chitosan. Dopants like H2SO4, newlineC8HF17O3S (perfluoro octane sulfonic acid (PFOS)), LiI and KI were used and solid newlinebiopolymer electrolytes were prepared. Results were analyzed with the help of various analytical techniques to study the ionic interaction, structure-property relationship and ion conductivity of the samples. The spectroscopic results confirmed the crosslinking character of chitosan with acids and also established the interactions and the complexation with salts. It was found that the ionic conduction behaviour in the newlineelectrolyte systems depends on the type and concentration of the salt used. The highest newlineroom temperature conductivity (1.05×10and#8722;4 S/cm) obtained from impedance measurement newlinefor LiI grafted chitosan electrolyte along with the dielectric and relaxation studies newlinesupported the segmental motion of the ion. Study on transference number revealed that newlinethe highest conducting samples were ionic conductors.