Valorization of food waste: Extraction of cellulose, lignin and their application in energy use and water treatment

Abstract

The study focuses on the isolation of the two important macromolecules of plant, lignin, and cellulose microcrystals (CMC) from agro-waste (peanut shell) and evaluates their potential application in biofuel production and wastewater treatment. The extraction of CMC was a two-step pretreatment process carried out by utilizing Sodium hydroxide followed by bleaching with Sodium Hypochlorite. The result showed that about 0.39 g/g of cellulose (dry wt%) was extracted from peanut shell waste. Scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction were considered for the characterization of cellulose and lignin. Also, besides, the saccharification and fermentation process was optimized. The maximum yield of reducing sugar was 3.16 mg/ml at pH (7) utilizing cellulose (5gm). A significant difference in bioethanol yield was observed between Zymomonas mobilis and Saccharomyces cerevisiae producing (0.471 g/g) and (0.637 g/g) bioethanol respectively. The Kraft lignin (1.5 mg/ml) and cellulose left after bioethanol extraction (CLA) were further used for crystal violet dye removal. The maximum adsorption capacity shown by lignin was about 87.64% followed by cellulose with 69% removal, whereas for CLA the removal capacity was highest to 98.21%. The finding demonstrates the potential of extracted cellulose for bioethanol production, and the challenges of utilizing CLA and lignin in wastewater treatment.