Valorization of Carbohydrates of Agricultural Residues and Food Wastes: A Key Strategy for Carbon Conservation

Abstract

The complete conservation of the carbon, hydrogen, and oxygen atoms of cellulose and starch can theoretically be achieved by their conversion to levulinic and formic acids. Similarly, hemicellulose can be converted to furfural and water with 100% atom economy. The valorization of carbohydrates of agricultural residues (banana-, orange-, and potato-peels, corn leaf and root, and rice husk), potential components of raw food wastes (corn, rice, potato, lettuce, onion, leek, vegetable, bean, and tomato), and cooked food wastes (rice noodle, spaghetti, risotto, noodle, bread, and biscuit) was demonstrated in the presence of sulfuric acid at 130 °C in γ-valerolactone as the green solvent to yield levulinic and formic acids as the two main products. Levulinic acid was also produced from furfural by its transfer hydrogenation with formic acid to furfuryl alcohol in the presence of Shvo’s catalyst followed by its acid catalyzed conversion to levulinic acid. Neutralization of the sulfuric acid in the reaction mixture with ammonium hydroxide resulted in an aqueous ammonium sulfate phase and a γ-valerolactone rich organic phase. Due to the salting out effect of the ammonium sulfate in the aqueous phase, levulinic acid and formic acid partitioned to the γ-valerolactone rich organic phase at >99.8% and >97.1%, respectively. The transfer hydrogenation of levulinic acid with formic acid in the presence of the Shvo’s catalyst resulted in the formation of 4-hydroxyvaleric acid, which readily underwent dehydration to yield γ-valerolactone, a green and sustainable liquid. The possibility of converting C5- and C6-carbohydrates to levulinic acid or γ-valerolactone is a great opportunity for carbon conservation with a carbon-economy higher than that for butanol or ethanol.

Eco‐friendly polymer composites: A review of suitable methods for waste management

“…[ 138 ] In a chemical route, studies have been carried out to obtain platform chemicals by the valorization of carbohydrates, the main components of biomass from food wastes. [ 139 ] Moreover, Choudhary and co‐workers [ 137 ] highlight the reuse of food wastes as an alternative to obtain a new class of materials. Rajeh and co‐workers [ 140 ] have also evaluated the use of food wastes as alternative to animal feed production.…”

Digital PCR as an Emerging Tool for Monitoring of Microbial Biodegradation

“…The basic process of dPCR is the random distribution of m molecules into n partitions. The average number of targets per partition (λ) follows Equation ( 5), which can be simulated by Poisson distribution as Equation (6). The m and C of an unknown sample can be easily calculated from the percentage of empty partitions P following Equations ( 7) and (8).…”

“…Our living habitats are detrimentally affected by the accidentally and deliberately released multitudinous contaminants, including both affirmative conventional pollutants and emerging contaminants [1][2][3][4][5]. Microbial-based degradation, occurring with series of chemical and microbial transformations, is the ultimate fate of contaminants with economic and environmental benefits [6,7]. Until now, plenty of contaminants have shown the biodegradability, even the widely used forms of plastics once proven recalcitrant to biodegradation [8,9].…”

Fermentation as a Strategy for Bio-Transforming Waste into Resources: Lactic Acid Production from Agri-Food Residues

“…Five batches of waste were collected from local agri-food industries: pear processing residues (PPR) (a mixture of unripe, overripe or damaged pears not suitable for market), tomato pomace (TP) (peels and seeds), potato pomace (PP) (damaged or broken tubers and peels), riches in carbohydrates [34], milk whey (MW), and ricotta cheese whey (RCW), which are the main by-products in cheese production processes, rich in proteins [35].…”