Affiliation:
1. Centro de Quimica Estrutural, Institute of Molecular Sciences and Departamento de
Engenharia Quimica, Instituto Superior Tecnico, Universidade de Lisboa, Av. Rovisco Pais,
1049-001 Lisboa
Abstract
Chitin and chitosan, which due to their wide applicability and abundance are of increasing interest to industries. Chitin is extracted from a wide range of living things by a variety of methods, which may be chemical or biological. Chitosan is obtained from the alkaline deacetylation of chitin by chemical or enzymatic processes. Due to their different polysaccharide chains, chitin and chitosan have different properties. Chitin is thus an insoluble polymer in most solvents, while chitosan is a soluble polymer in acid solvents because there is protonation of the amide group of this polymer, which makes it soluble in acid solvents. The source from which the greatest extraction of chitin occurs is from crustaceans such as shrimps, crabs, lobsters, crayfish, and clams. Extraction from crustaceans is an economical process, but seasonal, since most crustaceans are species that only belong to one season of the year. Since crustaceans are living beings that are not in abundance in the environment and in all seasons of the year, insects have been the subject of study for the extraction of chitin, since they exist in abundance in nature, throughout the year and in various parts of the world, being an excellent resource for a large-scale production of chitin and chitosan. Chitosan is the base for bioplastics and membranes.in this work a review of the existing methods and applications will be surveyed. Also, some green metrics regarding the synthesis of chitosan will be presented and discussed.