Extraction and in-depth characterisation of chitosan from African giant snail shells

Waste accumulation contributes significantly to environmental hazards affecting animals and humans. Despite their biodegradable nature, shells of snails, periwinkles, crabs, prawns, and shrimps decompose slowly over time, hence, constitute a significant amount of waste in the environment. This study investigated the physicochemical, structural, morphological, electronic transition, thermal, elemental, and particle size distribution properties of chitosan derived from snail shells, providing insights into its unique characteristics and potential applications, while promoting waste valorisation and environmental sustainability. A chemical method was used in this study, involving demineralization, deproteinization, decolouration, and deacetylation. The extraction process yielded 40% chitosan with a 99.5% degree of deacetylation, low moisture content (0.4317%), and protein content (0.7583%), indicating strong shelf stability and reduced allergenic potential. In-depth characterization using CHNS Analysis, Spectroscopic (FTIR & UV visible), structural (XRD), morphological (SEM/STEM), particle size distribution (DLS), Energy Dispersive X-ray Spectroscopy (EDX) and thermal gravimetry (TGA), confirmed the properties and characteristics of the chitosan, similar to the characteristic features reported for chitosan derived from shrimps and golden snail shells in the literature. The sharp, unimodal peaks depicted by DLS suggest that the chitosan is relatively uniform in size with a low polydispersity of 0.344, which is characteristic of chitosan. The TGA results revealed a two-step degradation pattern typical of chitosan, with good thermal resistance, supporting its suitability for applications requiring heat tolerance.