Characteristics of carbon dots derived chitosan-based shrimp shells deacetylated at different temperatures as a potential CO2 adsorbent

Abstract. This research addresses the need to efficiently utilize chitosan-based shrimp shells through synthesizing and characterizing CDs for potential CO2 applications. It aims to study the effect of deacetylation temperature on chitosan extracted using the chemical extraction method, the effect of deacetylation temperature of chitosan towards the yield of CDs, and the physical and chemical properties of CDs as a potential CO2 gas adsorbent. The deacetylation temperature was varied (55, 85, and 115 °C) to study its effect on the yield of CDs derived from chitosan-based shrimp shells modified with thiourea/KOH. The CDs were synthesized using the hydrothermal method. The synthesized CDs were characterized using various techniques, including FTIR, TGA, UV-vis spectrophotometry, fluorescence spectroscopy, CHNS/O elemental analysis, and FESEM-EDX. The best quantum yields of the synthesized CDs were determined to be 58.15% for 115 °C of deacetylation temperature. The results showed distinct peaks in the FTIR spectra, indicating the presence of C-H bonds, amide I and amide II bands, C-O-C, O-H, C-H, and C-H out-of-plane functional groups related to the chitosan structure. The thermal stability of chitosan was found to be at 300°C, where the surface morphology explained that the chitosan structure indicated potential modifications or surface alterations due to the synthesis process. The CHNS/O analysis results signify a notable alteration in chitosan to chitosan-based CDs, marked by a reduction in carbon content and the appearance of additional elements, suggesting effective carbonization and modification procedures. In summary, this research contributes to understanding CDs synthesized from chitosan-based shrimp shells, highlighting the importance of deacetylation temperature towards CDs’ quantum yield, and underscoring the potential of these synthesized CDs as CO2 adsorbents.