Integrated Crayfish waste-shells valorization for added value materials production: Calcium Hydroxide, Calcium Carbonate, Chitin, Chitosan, and N/S@Carbon quantum dots

Abstract

Food waste and byproducts landfilling practice produce remarkable amounts of hazardous gasses and substances due to the anaerobic decomposition process. Vertical integration of production and waste valorization are two of the methods adopted globally to reduce food waste following the circular economy and environmentally friendly practices spirit. In this study an integrated procedure is proposed for the valorization of wastes produced by a fish and crustaceous enterprise. Calcium hydroxide particles of size 6.32 µm and Calcium carbonate particles of size 16.9 µm were produced exhibiting meso-macro-pore structure with Sg=46m2/g and Sg=20m2/g respectively, similar to those reported in literature for applications such drug carriers e.t.c. Chitosan which was identified via NMR technique, exhibiting 91% deacetylation degree which means high water and gas barrier behavior, is also reported in this study. Finally, nitrogen/sulfur dopped carbon quantum dots were produced during this research, visually certified by UV luminescence experiments at 245 nm and 365 nm UV-light wavelength, exhibiting an identified via AFM technique mean size of 5.01 nm, and successfully tested for their advanced antioxidant capabilities via the DPPH assay and antimicrobial properties via MIC routine measurements with E. coli and L. monocytogenes. Concluding, the waste-shells from Crayfish and other crustaceous could be exploited for added value materials production yielding economic and environmental benefits.