Synthesis of Chitosan from Prawn Shells and Characterization of its Structural and Antimicrobial Properties

Abstract

Chitin was prepared from prawn shells waste by chemical treatments viz. demineralization, deproteinization and decolorization. Chitosan was prepared by deacetylation of chitin with 50% NaOH at 100 °C in the presence of nitrogen. Deacetylation was performed at different intervals of time to get a series of chitosans having different degrees of deacetylation. Prepared chitosans were characterized by molecular weight determination, degree of deacetylation, Fourier transform infrared (FTIR) spectroscopy and Scanning electron micrography (SEM). The degree of deacetylation of chitosans was calculated by acid base titration and potentiometric titration. The molecular weights of commercial and prepared chitosan (CS-4.0) samples were determined using the Mark- Houwink equation and were found to be 3.5 × 10⁵ (g/mole) and 3.3 × 10⁴ (g/mole), respectively. The degree of deacetylation was found to linearly increase with the increase of reaction time. FTIR spectra showed the characteristic peaks of chitin and chitosan. Antimicrobial screening results revealed that the prepared chitosan (CS-4.0) was equally or more biologically active than the commercial chitosan.