The byproduct-organic acids strengthened pretreatment of cassava straw: Optimization and kinetic study

Enhancing enzymatic saccharification of sunflower straw through optimal tartaric acid hydrothermal pretreatment

Sunflower straw, a usually neglected and abundant agricultural waste, has great potential for contributing to environmental protection realizing its high-value of valorization if utilizing properly. Because hemicellulose contains amorphous polysaccharide chains, relatively mild organic acid pretreatment can effectively reduce its resistance. Through hydrothermal pretreatment, sunflower straw was pretreated in tartaric acid (1 wt%) at 180 ^oC for 60 min to enhance its reducing sugar recovery. After tartaric acid-assisted hydrothermal pretreatment, 39.9% of lignin and 90.2% of hemicellulose were eliminated. The reducing sugar recovery increased threefold, while the solution could be effectively reused for four cycles. The properties of more porous surface, improved accessibility, and decreased surface lignin area of sunflower straw were observed through various characterizations, which explained the improved saccharide recovery and provided a basis for the mechanism of tartaric acid-assisted hydrothermal pretreatment. Overall, this tartaric acid hydrothermal pretreatment strategy greatly provided new impetus for the biomass refinery.

Application and prospect of organic acid pretreatment in lignocellulosic biomass separation: A review

As a clean and efficient method of lignocellulosic biomass separation, organic acid pretreatment has attracted extensive research. Hemicellulose or lignin is selectively isolated and the cellulose structure is preserved. Effective fractionation of lignocellulosic biomass is achieved. The separation characteristics of hemicellulose or lignin by different organic acids were summarized. The organic acids of hemicellulose were separated into hydrogen ionized, autocatalytic and α-hydroxy acids according to the separation mechanism. The separation of lignin depends on the dissolution mechanism and spatial effect of organic acids. In addition, the challenges and prospects of organic acid pretreatment were analyzed. The separation of hemicellulose and enzymatic hydrolysis of cellulose were significantly affected by the polycondensation of lignin, which is effectively inhibited by the addition of green additives such as ketones or alcohols. Lignin separation was improved by developing a deep eutectic solvent treatment based on organic acid pretreatment. This work provides support for efficient cleaning of carbohydrate polymers and lignin to promote global carbon neutrality.

Impacts of utilization patterns of cellulosic C5 sugar from cassava straw on bioethanol production through life cycle assessment

Integrated processes of whole plant cassava bioethanol production using full components including cellulosic C5 sugar are proposed. The impacts of different utilization patterns of cellulosic C5 sugar on bioethanol production are investigated by life cycle assessment. Results show that for cassava straw bioethanol, process using cellulosic C5 sugar performs better, and the NER, renewability and GWP (global warming potential) are 0.94, 1.09 and 2929 kg CO₂ eq. The integrated process WPC-2 that the cellulosic C5 sugar mash is fermented together with the cassava starch, is a better cellulosic C5 sugar utilization pattern with NER 1.49, renewability 2.20 and GWP 1579 kg CO₂ eq. The process WPC-2 shows the potential to approach cassava bioethanol in terms of energy and environmental emissions. The downstream products are investigated and the E85 fuel from WPC-2 has higher application potential.