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In this study, the structural factors controlling the enzymatic saccharification of rice straw cellulose were examined by preparing structure-modified rice straw samples such as dewaxed, alkali-treated, oxidized, and swollen rice straw. It was found that the initial enzymatic saccharification rate of the various structure-modified samples was largely controlled by the initial cellulose surface area of the cellulose unit. Although the presence of lignin limited the cellulose surface area, there was no strong relationship between the lignin content and the initial reaction. On the other hand, the long-term enzymatic saccharification of rice straw cellulose highly depended on the lignin removal rate (lignin content). It was also found that silica is not a crucial factor in controlling the enzymatic saccharification. [ABSTRACT FROM AUTHOR]

The release kinetics of esterified p -coumaric acid (PCA) and ferulic acid (FA) from rice straw under a mild alkaline condition were investigated to collect fundamental data for the design of a recovery process. The results showed that the straw size, NaOH concentration, and temperature were the key parameters governing release kinetics. The analysis demonstrated that FA is released considerably faster than PCA. The close relationship between lignin and the PCA dissolution indicates a reciprocal and/or simultaneous release. Moreover, PCA is broadly distributed in the lignin network but tends to be located more densely in the lignin fraction which is not easily solubilized by alkaline treatment. In contrast, the release of FA is strongly affected by removal of lignin fraction which is easily solubilized. These results suggest that the release kinetics are controlled by the accessibility of NaOH to their ester sites in the lignin/hemicellulose network, and by their localization. [ABSTRACT FROM AUTHOR]

Lignin is a renewable resource that can generate a variety of value-added benzene derivatives during hydrothermal and/or chemical hydrolysis treatment; the crucial task is to separate the targeted derivatives from the hydrolysate. This study aims to investigate the adsorption kinetics of lignin-derived benzene derivatives onto silicalite-1 crystal in an aqueous-phase system to examine the potential applicability of silicalite-1 to aqueous-phase kinetic separation. Functional groups substituted to benzene include –OH, –CH 3 , –CH 2 –CH 3 , –OCH 3 , –CHO, –COOH, and –CH 2 =CH 2 –COOH. First, the corrected diffusivity was compared among cresol isomers. Critical diameter of the isomers was found to be a key parameter, giving rise to significant differences in diffusivity. Interestingly, we also discovered a considerable difference (maximum over 4 orders of magnitude) in corrected diffusivity, even among mono - and para -substituted derivatives, although these sorbates have the same critical diameter. In particular, the carboxylic derivatives tended to exhibit extremely low diffusivities and to show S-shaped isotherms. The diffusivities were strongly affected by the melting point of the sorbates. These results indicate a strong sorbate-sorbate interaction (e.g., hydrogen-bonding between carboxylic groups) that considerably limits molecular mobility in the narrow channel. Our findings are relevant to research on silicalite-1 to aqueous-phase kinetic separation. [ABSTRACT FROM AUTHOR]

A simple ethanol concentration process composed of a simple adsorptive apparatus using a single adsorbent, i.e., molecular-sieving carbon (MSC), is proposed for small-scale bioethanol production. The process designed to comprise pre-concentration of ethanol through gaseous-phase adsorption onto MSC and selective dehydration driven by molecular-sieving during desorption was tested under various conditions. Among the candidate adsorbents, MSC 5A showed the highest maximum ethanol adsorption capacity (0.163 g g −1 ). It was confirmed that the adsorption temperature and the initial ethanol concentration in the broth are crucial factors for the adsorption stage. For the desorption stage, the water recovery temperature significantly affected the final ethanol concentration and the ethanol recovery. As a practical option for the application of the proposed system, sequential batch fermentation and ethanol recovery was successfully demonstrated. [ABSTRACT FROM AUTHOR]

In this study, molecular sieving carbons (MSCs) for biogas upgrading were successfully fabricated by a simple temperature controlled carbonization of moso bamboo ( Phyllostachys pubescens ) without energy consuming steps (i.e. char activation and pore modification). As the carbonization temperature increased from 600 to 900 °C, the specific surface area of bamboo charcoals increased and the pore size distribution of bamboo charcoal became narrower and closer to the dimensions of CH 4 (0.38 nm). Bamboo charcoals had a more disordered carbon stacking structure than commercial MSC and contained more surface oxides, which contribute to greater surface reactivity than commercial activated carbon. Bamboo charcoal carbonized at 900 °C had the highest CO 2 adsorption capacity (121.6 g kg −1 ), even higher than commercial MSC (102.88 g kg −1 ). Despite the poor kinetic CO 2 adsorption properties of bamboo charcoals compared to commercial MSC, synthetic biogas (60% CH 4 + 40% CO 2 ) was successfully upgraded to concentrated CH 4 (>90%) by small-scale pressure swing adsorption using bamboo charcoal. It is expected that bamboo charcoals can contribute to sustainable small-scale biogas upgrading. [ABSTRACT FROM AUTHOR]

Graphene quantum dots (GQDs) were formed by liquid-phase exfoliation in an ultrasonic bath using platelet graphite nanofibers (PGNFs) as the raw material and dimethyl sulfoxide (DMSO) as the exfoliation agent. PGNFs, carbon fibers with graphene nanosheets stacked perpendicular along the fiber axis, were sectioned layer by DMSO for 3 h with ultrasonic assistance to create GQDs. The diameters of the derived GQDs were in the range of 10–30 nm and fewer than five graphene layers were formed. X-ray photoelectron spectroscopy analysis revealed that no functional groups were grafted onto the GQDs during the process, indicating that the synthetic route produced high-quality GQDs. [ABSTRACT FROM AUTHOR]