Isolation and Characterization of Cellulose from Cocoa Shell Waste: A Green Chemical Implementation Approach

This study analysed the effects of strong acid and green acid usage on the physical and chemical properties of cellulose isolated from cocoa shell waste. The results showed that employing pro analysis and commercial citric acid as a green acid as well as strong acids such as hydrochloric, nitric and sulfuric acids, resulted in the presence of typical functional groups of cellulose, i.e., O-H, C-H and C-O bonds. The presence of lignin as an impurity was detected by FTIR at 1500 cm^-1 (aromatic C=C bonds) in the GM and HA5 samples which used 5 % NaOH in the delignification process. Employing 17.5 % NaOH and both strong and green acids produced no lignin peaks in the FTIR spectra. Samples were characterized using XRD, and the crystallinity index showed that using pro analysis and commercial citric acid on the isolated cellulose contributed to a poor crystal form compared to the use of strong acid. It also showed that 17.5 % NaOH and a strong acid were more effective than a green acid in terms of crystallinity. However, hydrolysis with nitric acid caused one of the main functional groups of cellulose to be lost and destroyed the main structure. It was also observed that green acids produced a dark brown powder, while strong acids tended to produce powders that were dull brown to yellow. This work demonstrates that optimized cellulose isolation using green chemicals is possible for specific applications.