Cupuaçu husk (CH) is the waste of a common fruit from a native species of the Brazilian Legal Amazon. The current study investigated the influence of ultrasound (US) combined with aqueous, acid, alkaline, and ionic liquid (IL) pretreatments on the chemical and physical aspects of CH and the yield of chemical platforms production, 5-hydroxymethylfurfural (HMF) and furfural (FF), using IL. Scanning electron microscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy were used to feature the raw and pretreated biomass. The highest levels of glucose (9.90 g L-1) were observed in the liquid fraction resulting from the acid + US pretreatment followed by acid hydrolysis. The IL + US pretreatment recorded the best performance in removing lignin. Based on XRD analyses, ultrasound increased crystallinity of all pretreated samples as a result of the removal of cellulose’s amorphous fraction. However, it promoted accessibility to adopted reagents by increasing biomass exposure due to cavitation. The best yields of HMF and FF were recorded from hydrolysis of the solid fraction resulting from the acid + US (12.94%) and alkaline + US (48.84%) pretreatment, respectively. These results indicate satisfactory performance of ultrasound assisted pretreatments to the simplified and economic conversion of biomass into value-added products.

Abstract Lignocellulosic waste is a valuable source of energy, fuels, and raw materials for the chemical industry. In this study, the potential of cupuaçu husks, derivative from a typical fruit of the Brazilian Amazon, was evaluated. Therefore, biomass was submitted to acid hydrolysis and pyrolysis, and the contents of sugars, by-products, bio-oil compounds, and bio-oil theoretical energy potential were determined. X-ray diffraction, High performance liquid chromatography, Fourier-transform infrared and Gas chromatography mass spectrometry analyzes were used. The hydrolysate has considerable sugar levels (31.7%) and presence of relevant by-products including furfural, levulinic acid and hydroxymethylfurfural. Bio-oil contained a variety of phenolic compounds, and its theoretical energy potential suggested usability of cupuaçu husks for energy generation. Economic analysis showed that commercialization of bioproducts obtained by biomass hydrolysis and pyrolysis could be highly profitable. These outcomes indicate a range of applications for cupuaçu husks in biorefinery processes and potential to promote sustainability and social development.

Abstract In the current search for renewable energy sources, residual biomass has been highlighted as a potential source of chemical compounds that are currently obtained from petroleum. Among the derivatives obtained from this, 5-hydroxymethylfurfural and furfural are considered key parts in this process as they are key compounds in the fine chemical industry. This work aims at the use of the rice husks and soybean peel for the synthesis of 5-hydroxymethylfurfural and furfural using the ionic liquid [BMIM][Br]. The physical pre-treatment of biomasses was carried out followed by acid hydrolysis. For the synthesis of the furanic compounds, different temperatures and reaction times were used. The products obtained in each step were analyzed by infrared spectrophotometry and by high performance liquid chromatography. The best yields for rice husks was obtained with 4 hours of reaction at 120 °C (34%) and for soy peel with 3 hours of reaction at 120 °C (59%), for furfural production. For 5-hydroxymethylfurfural production the yields were 8.7% and 3.4% for rice and soy husks, respectively. It was found that glucose was the main group related to bio-products obtaining.