Simultaneous organosolv pretreatment and detoxification of agro-biomass for efficient lignin extraction and characterization

Abstract

A sequential acid extraction approach using organic acid followed by peroxy acid to enhance the recovery of lignin from Bambusa bambos was investigated. The conventional organic acid process was utilized in the pulping step to recover lignin. The residual organic acid-treated pulp was subjected to additional delignification step with peroxy acid to recover additional lignin. A five-level central composite design (CCD) was used to optimize this sequential organic acid followed by peroxy acid extraction process. Three factors, organic acid and peroxy acid concentration, biomass concentration, and duration of extraction, were optimized to maximize OAT–lignin (organic acid-treated lignin) and PAT–lignin (peroxy acid-treated lignin) recovery. Analysis of variance (ANOVA) was used to statistically analyze the significance of these variables on lignin recovery. The optimization process (83.45% v/v organic acid, 8.65% w/v biomass, and 3.35 h duration of extraction) resulted in the maximization of OAT–lignin recovery (123.6 mg/g of biomass) in the organic acid treatment step. The peroxy acid treatment was optimized (83.81% v/v peroxy acid, 6.41% w/v OAT pulp, and 3.23 h duration of extraction) to show that additional 47.2 mg/g of PAT–lignin can be recovered in the delignification step. The physicochemical characteristics of the lignin recovered with the sequential strategy were determined by fourier transform infrared spectroscopy (FTIR), thermo gravimetric analyzer (TGA), and 1H Nuclear magnetic resonance spectroscopy (1H NMR). The results show that the sequential treatment strategy significantly enhances the lignin extracted from Bambusa bambos.