Production and Properties of Different Molecular Weights of Chitosan from Marine Shrimp Shells

Abstract

The present study investigates the production of ten different molecular weights of chitosan products from shrimp shells collected from Alexandria (the second largest city in Egypt after Greater Cairo) and their properties were investigated and compared with standard chitosan sample. Extraction of chitin from shrimp shells at laboratory scale was done and it has depended on three steps: deproteinization (DP), demineralization (DM), and decolourization (DC). The optimum conditions for the best yield and color of the chitin products included 5% sodium hydroxide solution in DP step, an acid concentration of 3% HCl in DM step at room temperature, and keeping the product in potassium permanganate solution (1%, w/v) for 1 h, followed by keeping it in oxalic acid (1%, w/v) for the process of DC. Chitin yield ranged from 25.6 to 51.60% depends on shells dry weight and age of the shrimp samples. Chitosan was then obtained by deacetylation (DA) of chitin with sodium hydroxide pellets at weight ratio of 1:5, respectively. The yield of chitosan products was ranged from 16.20 to 33.40% based on dry weight. Different intrinsic properties included ash content, degree of deacetylation (DDA), solubility, viscosity, and average molecular weight of extracted chitosan products were determined through standard methods. The FT-IR and H-1-NMR spectra of the extracted products were studied with satisfactory results.