Chemical composition retention perspective: research on pretreatment production of lignocellulose bioethanol

Improving lignocellulosic ethanol production requires pretreatment methods that yield a solid-phase composition conducive to efficient enzymatic saccharification. In this study, kapok fiber was pretreated using autohydrolysis, dilute acid, and alkaline methods at practical severities, followed by standardized enzymatic hydrolysis. Glucose yields, based on pretreated solids, ranged from 19–70% for autohydrolysis, 19–53% for dilute acid, and 19–62% for alkaline pretreatment. The post-pretreatment composition was assessed using two novel metrics: Relative Composition Ratio (RCR), which quantifies the proportion of each component in the pretreated solid relative to its original proportion, and Absolute Composition Ratio (ACR), calculated by multiplying solid yield by the RCR. Response surface modeling revealed that lower hemicellulose retention in the recovered solid was the primary factor correlating with higher glucose release, while preserving cellulose and limiting lignin increase were beneficial, but secondary, within the tested conditions. This framework provides actionable composition windows for guiding pretreatment targeting and cross-method screening, using consistent dry-basis accounting.