Uso de cloreto de colina no pré-tratamento da fibra de coco verde visando à produção de etanol 2G e a valorização da lignina como agente coagulante

Abstract

One way for coconut companies to increase their cost-benefit and reduce the dependence on non-renewable energy sources is by using green coconut fibers (GCFs) in value-added products. In this study, GCFs were pretreated with choline chloride ([Cho][Cl]) in an acidified medium with diluted sulfuric acid to enrich cellulose on the solid fraction and lignin on the liquid fraction. The aim was to evaluate the feasibility of obtaining 2G ethanol from simultaneous (SF) and semi-simultaneous fermentation (SSFS) strategies. The study also examined the recycling of pretreatment effluents and their impact on enzymatic hydrolysis and fermentation stages. The pretreatment was conducted in an autoclave (1 atm, 121 °C) without or with diluted sulfuric acid (1.0%, w/w), using different concentrations of [Cho][Cl] (50 and 75%, w/w) and incubation times (25 and 50 min). The pretreated GCFs were then submitted to enzymatic hydrolysis (20 FPU/g), and the best condition was chosen for the SF and SSFS fermentation processes. Additionally, the research has investigated the removal of lignin from the liquid fraction for use as a coagulating agent in oil-contaminated water. The results showed that pretreatment with [Cho][Cl] at a concentration of 75% (w/w) in 50 min of reaction time and an acidified medium with 1% (w/w) of diluted sulfuric acid (C75/50m/H) as the best pretreatment to increase the conversion of cellulose into glucose, reaching 22.6 g/L of free sugar. The SSFS achieved the best efficiency of 32.43% (23.2 g/L alcoholic concentration) and a productivity of 0.483 g/L.h for the condition of 20% solid load in obtaining 2G ethanol. Furthermore, 82.6% of the lignin was recovered from the liquid fraction of this same pretreatment, wherethe application of lignin in the treatment of water contaminated with oil achieved removal of 99% of oil from the aqueous phase. Therefore, GCF pretreated with choline chloride has the potential for 2G ethanol production. Furthermore, the use of lignin generates an adsorbent with the potential to be used in different processes, including in the petroleum industry.