Optimized high-yield synthesis of chitin nanocrystals from shrimp shell chitin by steam explosion

Abstract

This study attempted for the first time to prepare chitin nanocrystals (ChNCs) from shrimp shell chitin using steam explosion (SE) method. Response surface methodology (RSM) approach was used to optimize the SE conditions. Optimum SE conditions to acquire a maximum yield of 76.78 % were acid concentration (2.63 N), time (23.70 min), and chitin to acid ratio (1:22). Transmission electron microscopy (TEM) revealed the ChNCs produced by SE had an irregular spherical shape with an average diameter of 55.70 ± 13.12 nm. FTIR spectra showed ChNCs were slightly different than chitin due to a shift in peak positions to higher wavenumber and higher peak intensities. XRD patterns indicated ChNCs were a typical α-chitin structure. Thermal analysis revealed ChNCs were less thermally stable than chitin. Compared to conventional acid hydrolysis, the SE approach described in this study is simple, fast, easy, and requires less acid concentration and acid quantity, making it more scalable and efficient for synthesizing ChNCs. Furthermore, the characteristics of the ChNCs will shed light on the potential industrial uses for the polymer.

Keywords: Acid hydrolysis; Chitin nanomaterials; Circular economy; Nanochitin; Waste valorization.