Characterization of Citrus Peels for Bioethanol Production

Citrus peel waste is an attractive feedstock of lignocellulosic biomass which can turn into bioethanol. In the present study, several characteristics of citrus peel are illustrated for investigating its suitability for energy generation. The proximate analysis, elemental analysis, FTIR analysis, TGA and DSC studies are conducted for the characterization of citrus peels. From ultimate analysis, it is observed that less amount of nitrogen and sulfur and good amount of carbon, hydrogen and oxygen which can lead to higher ethanol yields. Higher heating value of sweet lime peel and orange peel is obtained as 14,853 and 15,690 kJ/kg respectively which are comparable to other biomass feedstock for biofuel production. FTIR spectra give the information about the presence of cellulose, hemicellulose, lignin, and pectin. The extracted lignin, pectin, acid detergent fiber and neutral detergent fiber from biomass are subjected to thermal degradation studies. The results of thermogravimetric analysis show that the decomposition pattern is similar to that of other lignocellulosic biomass viz., bagasse, rice straw. At normal heating rate, the degradation of hemicellulose occurs at less than 350°C, cellulose degradation between 250 and 500°C, and lignin degradation is gradually distributing throughout the process even after 500°C. There is no definite weight reduction happens since lignin is more thermostable than cellulose and hemicellulose. DSC profile of the peel shows an endothermic reaction initially and exothermic in nature from 200°C. The results from the characterization studies show that the peels of citrus fruits have good potential for energy generation.