Preparation And Characterization Of Alkali Lignin-Chitosan Composite Membrane

Alkali lignin is the main by-product in paper industry in China, whose direct emission will cause serious environmental pollution and result in a great waste of resources. As alkali lignin is aromatic renewable resource, its development and utilization can not only reduce environmental pollution, but also alleviate the crisis of resources to maintain sustainable development.This paper is to make alkali lignin membrane material and explore the usage. It has produced alkali lignin-chitosan mixed membrane and alkali lignin-chitosan blended membrane. Because of the low reactivity of alkali lignin, it should be modified by formaldehyde under the alkaline condition firstly, which makes the total hydroxy increase by 57.6%, hydroxy-alcohol 150.9%, and phenol hydroxyl 16.2%, then gets the more active hydroxymethyl alkali lignin. With hydroxymethyl alkali lignin and chitosan, it has synthesized alkalilignin-chitosan mixed membrane and alkalilignin-chitosan blended membrane, measured the physical properties of the membrane and explored the usage. Alkalilignin-chitosan mixed membrane has the well chelating performance on the copper (Ⅱ), and its static saturated adsorption capacity is 303.75μg/cm~2 , which increases by 50.2% compared with chitosan membrane; filtering the same dynamic 500 ml copper sulfate solution, its unit area of the cumulative chelate copper (Ⅱ) is 47.41μg/cm~2, which is increases by 52.39% compared with chitosan membrane. The crosslinking reactive membrane, which is produced with glutaraldehyde modified hydroxymethyl alkali lignin and chitosan, has excellent anti-acid performance and can maintain integrity and strength in the pH = 0.1 condition, but its chelating property of copper is not better than the chitosan membrane. This paper also discusses the reactive alkali lignin chitosan membrane's sustainably-releasing effect on urea and its fixing effects on laccase. Alkali lignin based membrane has been successfully produced, but its application still needs further study and exploration. It may be used in the fertilizers or pesticides, agricultural film, and other aspects of performance in the future.