RSM-Driven Optimization of Lignin Removal from Water Hyacinth under Alkaline Conditions

Excess lignin hinders the effective use of water hyacinth (Eichhornia crassipes) for biofuel and bio-based material applications, even though, as an invasive water plant, it represents a potential source of lignocellulosic biomass. This study attempts to optimize alkaline delignification with a focus on the removal of lignin. Response surface methodology (RSM) was used to statistically analyze the effect of delignification NaOH (۲-۸% w/v) concentration, temperature (۴۰-۸۰ ℃), and reaction time (۳۰-۱۲۰ min) while keeping a constant solid-to-liquid ratio of ۱:۱۰. These ranges were selected based on preliminary experiments and literature reviews to cover the region, where significant delignification occurs while maintaining industrial relevance. A Box–Behnken design was used to model the data for evaluation. All other factors being constant, the study found NaOH concentration and temperature to be the most significant factors in lignin removal. With the optimized conditions of ۸% NaOH, ۶۰ oC, and ۱۲۰ min reaction time, a residual lignin content of ۲.۲۱۵% was achieved. The model developed showed strong predictive capabilities with an R۲ value of ۰.۹۵. The process was effective as confirmed by FTIR and SEM analyses, showing that the lignin-related functional groups were reduced and the biomass porosity was increased. This study demonstrates the optimization process of delignification of water hyacinth that can add value.

کلیدواژه ها:

water hyacinth ، alkaline delignification ، residual lignin ، RSM