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Lignocellulosic biomass represents an excellent alternative to fossil fuels in terms of both energy production and raw material usage for a plethora of daily-use products. Organosolv pretreatment is a fractionation technique able to separate lignocellulosic biomass into individual streams of cellulose, hemicellulose, and lignin under controlled conditions. Sawdust, the by-product of sawmill processing of Picea abies wood, was the subject of our investigation in this work. The aim was to evaluate the effects of different parameters of the organosolv process of spruce sawdust on the yield of components and how this affects the enzymatic saccharification of cellulose. Sixteen distinct pretreatments were performed with ethanol concentrations of 50 and 60% v/v at 180 and 200 °C for 15 and 30 min. Half of the pretreatments contained 1% sulfuric acid as a catalyst, while the other half were acid-free. Thereafter, the effects of different variables on the yield of products were assessed and compared to determine the ideal pretreatment condition. The results showed that cellulose-rich pulps, with cellulose content as high as 55% were generated from an initial mass of 37.7% spruce sawdust with the reactor operating at 180 °C for 30 min using 60% ethanol and 1% sulfuric acid. With the pretreatments performed with the catalyst at 200 °C, hemicellulose was almost entirely removed from the pulps obtained. The recovered hemicellulose fraction was composed mainly of monomers achieving up to 10 g/100 g of biomass. Delignification values of up to 65.7% were achieved with this pretreatment technique. Fractionated lignin presented low levels of sugar and ashes contamination, with values as low as 1.29% w/w. Enzymatic saccharification of the pretreated pulps yielded 78% cellulose hydrolysis, with glucose release higher than 0.54 g/g of biomass, indicating the potential of the pulps to be applied in a fermentation process. [ABSTRACT FROM AUTHOR]

Metal nanoparticle synthesis via environmentally friendly methods is gaining interest for their potential advantages over conventional physico-chemical approaches. Herein, we propose a robust green synthesis route for lignin-modified silver nanoparticles, utilizing the recovery of lignin as a renewable raw material and exploring its application in valuable areas. Through a systematic approach combining UV-Vis spectroscopy with AAS and DLS, we identified repeatable and scalable reaction conditions in an aqueous solution at pH 11 for homogeneous silver nanoparticles with high uniformity. The TEM median sizes ranged from 12 to 15 nm with circularity between 0.985 and 0.993. The silver nanoparticles yield exceeded 0.010 mol L−1, comparable with traditional physico-chemical methods, with a minimal loss of silver precursor ranging between 0.5 and 3.9%. Characterization by XRD and XPS revealed the presence of Ag-O bonding involving lignin functional groups on the pure face-centered cubic structure of metallic silver. Moreover, the lignin-modified silver nanoparticles generated a localized thermal effect upon near-infrared laser irradiation (808 nm), potentially allowing for targeted applications in the biomedical field. Our study showcases the potential of lignin as a renewable reducing and capping agent for silver nanoparticle synthesis, addressing some shortcomings of green synthesis approaches and contributing to the development of suitable nanomaterials. [ABSTRACT FROM AUTHOR]

Carbonic anhydrase (CA) is considered an efficient enzyme for fermentation systems exhibiting a wide range of applications, enhancing both the efficacy and output of the fermentation process. The present study aimed to evaluate the production of acidogenic biohydrogen (bioH2) and volatile fatty acids (VFA) using forest residues as a renewable feedstock. Specifically, the study examined the integration of CA derived from Desulfovibrio vulgaris into the acidogenic fermentation (AF) process. The experimental procedure involved a cascade design conducted in two distinct phases. In phase I, the concentration of CA in the AF was systematically optimized, with glucose serving as the substrate. In phase II, three influential parameters (pH, pressurization with in situ generated gas and organic load) were evaluated on AF in association with optimized CA concentration from phase I. In phase II, glucose was replaced with renewable sugars obtained from forest residues after steam explosion pretreatment followed by enzymatic saccharification. The incorporation of CA in AF was found to be beneficial in steering acidogenic metabolites. Alkaline conditions (pH 8) promoted bioH2, yielding 210.9 mLH2 gCOD -1, while introducing CA further increased output to 266.6 mLH2 gCOD -1. This enzymatic intervention improved the production of bioH2 conversion efficiency (HCE) from 45.3% to 57.2%. Pressurizing the system accelerated VFA production with complete utilization of in situ produced H2 + CO2 compared to non-pressurized systems. Particularly, caproic acid production was improved under pressurized conditions which was accomplished by the targeted enrichment of chain-elongating bacteria in the mixed culture. The microbial diversity analysis showed the dominance of Firmicutes suggesting a significant degree of adaptation to the experimental contexts, leading to an enhanced production of acidogenic metabolites. [ABSTRACT FROM AUTHOR]