Comparative study on microwave-assisted and conventional chitosan production from shrimp shell: Process optimization, characterization, and environmental impacts

Chitosan, obtained from chitin in crustacean exoskeletons, has attracted interest due to its biocompatibility and versatility of application in several industries. Chemical methods are traditional for chitosan production but present environmental challenges. This study comprehensively assesses the microwave-assisted method as a greener alternative compared to conventional deacetylation. Morphological, thermal, and chemical properties, yield, and environmental impacts are evaluated. Experimental results indicate microwave-assisted deacetylation produces chitosan with excellent properties, with a high degree of deacetylation (close to 90%) and yield (above 50%). The Life Cycle Impact Assessment (LCIA) study highlights fossil resource scarcity, climate change, human non-carcinogenic toxicity, and terrestrial ecotoxicity as some of the most relevant environmental impacts, considering the Brazilian scenario. Notably, the difference in reaction time (240 vs 16 min) indicates the substantial advantage of the non-conventional technique in terms of reaction time, also reducing the energy consumption during deacetylation from 382.1 to 8.9 kJ per gram of chitosan produced by conventional and microwave-assisted methods respectively. However, LCIA shows NaOH use during deacetylation as a notable contributor to environmental effects, highlighting the necessity for minimizing its presence. Despite this, microwave integration leads to diminished environmental impact. This research highlights the environmental benefits of microwave-assisted deacetylation for more sustainable chitosan production.