Eco-friendly purification process of chitin contained in shrimp shells by application of the Definitive Screening Design experiment plan

Chitin is a biopolymer contained in shrimp shells, its extraction requires costly and polluting processes. However, it has a wide range of applications, mainly in the pharmaceutical and automotive sectors. The aim of this work is to improve the chitin purification process by using an experimental design to reduce the cost of the process and its effects as much as possible. The "Definitive Screening Design" (DSD) discovered in 2011, offers an attractive alternative to existing designs by screening and optimizing at the same time. The quality of the obtained biopolymer was expressed by crystallinity index that was extracted from the X-ray diffraction (XRD) data, which reveals a crystallinity index (CrI%) about 87% for optimal values of 0.5 M for the concentration of acid chloride and 40 °C for the demineralization temperature for three hours. To identify the chitin and assess its quality a parameter called acetylation degree was calculated from Fourier Transform Infrared spectrophotometry (FT-IR) results, that revealed an optimal value about 77% for an acid chloride concentration of 1.5 M, a sodium hydroxide concentration of 0.5 M, and a temperature of 40 °C for the demineralization and deproteinization steps. Scanning Electron Microscopy (SEM) analysis was performed to observe the morphology of purified chitin, which reveals a homogeneous surface with block formation while using HCl as demineralization agent in the process, so it is considered the most suitable acid to use in this step.

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