Structural characterization of polymeric chitosan and mineral from Omani shrimp shells

Shrimp shell waste is a burden nowadays globally due to its environmental pollutions. However, shrimp shells contain various ingredients such as chitosan, chitin, minerals, and proteins, which are essential for biomedical, agriculture, and industrial sectors. Chitosan is a polymer, and it is characterized by its biocompatibility, biodegradability, and non-toxicity. This study aimed to isolate a good quality chitosan polymer from the shrimp shells waste and characterize it by using spectroscopic methods. Initially, the collected shrimp shells were dried and ground for chemical treatment, collected from different regions of Oman. The coarse samples were dimerization, deproteinization, deacetylation and discoloration by using 1 M hydrochloric acid, 12.5 M sodium hydroxide, and 12 M hydrogen peroxide solution to give the corresponding products. Finally, the isolated chitin samples were deacetylated by microwaving at high temperature and pressure for 15 min. The yield of chitosan was approximately 53.31%, which 8.46 ± 0.06 gm, 7.02 ± 0.01 gm and 5.31 ± 0.01gm were the average weight yield after the demineralization, deproteinization and deacetylation processes, respectively. The degree of deacetylation of the extracted chitosan from the shrimp shells was very high of about 97.35% as calculated and identified by using Nuclear Magnetic Resonance spectroscopy. The content of calcium and phosphorus minerals of the chitosan was 117.6 ± 0.01 and 119.12 ± 0.09 parts per million (ppm), respectively, which was determined by using Inductive Coupled Plasma-Optical Emission Spectroscopy. The morphological feature of the chitosan and standard was examined using Scanning Electron Microscopy and EDX, and the results showed no big morphological difference between the two samples and the elemental compositions were almost the same. The results showed that the obtained isolated chitosan from shrimp shells was highly deacetylated compared to standard chitosan, and it could be useful for the preparation of commercial, industrial products, and pharmaceutical drugs.