Design and experimental study on closed-loop process of preparing chitosan from crab shells.

Area of Science:

• Biotechnology
• Green Chemistry
• Materials Science

Background:

• Crab shells are a rich source of chitin, a precursor to chitosan.
• Traditional chitosan extraction methods often involve harsh chemicals and generate significant waste.
• Developing sustainable and eco-friendly processes for chitosan production is crucial.

Purpose of the Study:

• To design a green and comprehensive utilization process for preparing chitosan from crab shells.
• To explore the recovery and recycling of key reagents.
• To convert waste components into valuable byproducts.

Main Methods:

• Decalcification of crab shells using glutamic acid.
• Deproteinization and deacetylation using a potassium hydroxide/isopropanol mixture.
• Characterization of chitosan using FT-IR, DSC, XRD, and SEM.
• Recovery and recycling of glutamic acid and isopropanol.

Main Results:

• High-quality chitosan with a deacetylation degree of 88.7% and molecular weight of 792.1 kDa was prepared.
• Recovery rates for glutamic acid and isopropanol were 95.56% and 88.14%, respectively.
• Calcium carbonate and protein were converted into calcium hydrogen phosphate and fertilizer, respectively, demonstrating comprehensive utilization.

Conclusions:

• The developed process is environmentally friendly and economically viable.
• It enables the efficient production of high-purity chitosan from crab shells.
• This method offers a sustainable solution for waste valorization and resource recovery.