查看更多>>摘要：? 2021Aucoumea klaineana Pierre (okoumé) is a tropical hardwood used in the timber industry in the Congo area to produce veneers and plywood. This paper described the utilization of sapwood co-products from this industry according to a biorefinery approach to generate both bioethanol and lignin. A batch Steam Explosion (SE) was used as a pretreatment after acid impregnation (H2SO4 0.25% or 0.50% w/w) at various pressure (8–19 MPa) and residence times (2.5–7.5 min). The impact of the process was examined at the molecular and parietal scales. The pulp composition was examined in terms of lignin, glucose and xylose content, cellulose crystallinity (CrI %) and degree of polymerization (DP). The conditions of high pretreatment severity led to an almost total xylans removal (residual xylans < 2%), to a strong decrease of cellulose DP and to a lignin fragmentation and relocation increasing its extractability with ethanol as solvent. At the parietal scale, the effect of the pretreatment on wood cell wall was analyzed by optical microscopy after dyeing, fluorescence microscopy and scanning electron microscopy. Enzymatic hydrolysis of the cellulosic pulps was experimented using commercial cellulase from T. Reesei. A SE pretreated wood produced at 210 °C during 5 min with an impregnation with 0.25 w/w% acid resulted in a glucose yield > 80% with an excellent fermentability into ethanol by S. Cerevisiae. Using these operating conditions, one ton of okoumé sapwood could produce 112 kg of ethanol and 82 kg of high purity lignin.
查看更多>>摘要：? 2021 Elsevier B.V.A biomass-derived carbon aerogel (CA) was prepared and employed as an efficient metal-free and green carbon-based catalyst for peroxymonosulfate (PMS) activation to degrade tetracycline (TC). The surface functional groups, morphology, and other properties of the CA were characterized using various methods. Different carbonization temperatures were used to produce CA samples to control the oxygen-containing functional group content and defect degree, both of which play important roles in PMS activation. The carbonization temperature showed a clear negative correlation with the oxygen-containing functional group content on the CA surface, while exhibiting a positive correlation with the degree of defects in the CA. The optimal temperature for producing the CA was 300 ℃ owing to the high oxygen-containing functional group content and low loss rate. Neutral and weakly alkaline conditions were conducive to TC removal. Under optimal conditions, 93% removal of TC could be achieved within 90 min. The results of reactive oxygen species (ROS) quenching experiments and electron paramagnetic resonance (EPR) spectroscopy indicated that both non-radical species (1O2 and electrons) and radical species (?OH and SO4??) resulted in the removal of TC. 1O2 was identified as the main activated ROS. This study deepens our understanding of the preparation of biomass-derived carbon aerogels and control of the oxygen-containing functional group content and defect degree for improving the pollutant removal efficiency.
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Elsevier