Supercritical water valorization of chitin in a continuous reaction system: Chitin nano-particles.

Abstract

Chitin is an abundant biopolymer of [-1,4-poly(n-acetyl-D-glucosamine)] units, produced by crustaceans, mollusks, insects, and fungi. Nowadays, chitin is discarded in massive amounts (6–8 million tons/year) as waste from the seafood industry, being underexploited as biomass resource[1]. Chitin is of great interest as a biocompatible and biodegradable material, gaining importance in the formulation of phytosanitary products, thanks to its elicitor activity in plants[2]. It is also considered as a source of oligosaccharides and biologically active monomers, N-acetylglucosamine (depolymerization) and glucosamine (deacetylation). Several studies have shown that chitin, like cellulose, can be dissolved and hydrolyzed in supercritical water (SCW) due to the change in its properties (water density and ionic product, among others); however, due to the high chitin crystallinity, this process occurs less easily[3]. The present work aims to investigate the mechanisms of chitin transformation in SCW medium (400°C and 25MPa), using ultrafast sudden expansion microreactors (SEMR) in a continuous system (residence time 0.1s - 2s).