maleic-acid and nitrobenzene

The aim of this study was to investigate the effects of different acid pretreatments on the hydrolysis of biomass and ethanol production. Maleic, oxalic, and sulfuric acids were used individually as catalysts. The fermentable sugar concentration in hydrolysate was high at more than 30 g/L, which obtained at the dicarboxylic acid pretreatment. On the structural change of pretreated biomass, the S/G ratio ranged from 1.7 to 2.0, which was lower than that of raw material. The amount of phenolic OH group was significantly increased by acid pretreatment, which ranged 17.5-32.8%, compared to 4.7% of the raw material. The amounts of phenolic OH group in lignin sensitively affected simultaneous saccharification and fermentation. The maleic acid pretreated biomass, which included 17.5% of the phenolic OH group, was very effective for attaining high glucose yields and ethanol yield, after simultaneous saccharification and fermentation. At the same time, the highest ethanol yield was 0.48.

Topics: Acids; Biomass; Carbohydrate Metabolism; Carbohydrates; Ethanol; Fermentation; Hydrolysis; Maleates; Nitrobenzenes; Oxalic Acid; Oxidation-Reduction; Sulfuric Acids; Wood

Experiments have been performed with a semicontinuous batch reactor to compare the degradation efficiency of nitrobenzene in aqueous solution by the ultrasonic processes of single field, opposite dual fields, and orthogonal dual fields. Ultrasound with dual fields can improve the degradation efficiency of nitrobenzene compared to that of single field, and the improvement phenomenon is even more pronounced in the orthogonal dual-field system. The degradation reactions of nitrobenzene in the three processes all follow the pseudofirst-order kinetic model. The mechanism investigation indicates the degradation proceeds via hydroxyl radical (*OH) oxidation. The enhancement efficiency of orthogonal dual fields is attributed to an obvious synergetic effect, which accelerates the *OH initiation from 0.28 micromol L(-1) min(-1) for a single field to 0.98 micromol L(-1) min(-1) compared with 0.42 micromol L(-1) min(-1) for opposite dual fields, resulting in rapid formation of an increased diversity of byproducts and an advanced degree of mineralization of total organic carbon (TOC). The introduction of an ultrasonic field placed in the different spatial position causes a variable kinetic order during the removal of TOC. The degradation byproducts are identified by gas chromatography mass spectrometry and ion chromatography, including p-, m-nitrophenol, malonic acid, nitrate ion, 4-nitrocatechol, phenol, maleic acid, oxalic acid, hydroquinone, 1,2,3-trihydroxy-5-nitrobenzene, and acetic acid.

Topics: Acetic Acid; Carbon; Catechols; Chromatography, Gas; Hydroquinones; Hydroxyl Radical; Ions; Kinetics; Maleates; Malonates; Nitrates; Nitrobenzenes; Nitrophenols; Oxalic Acid; Ultrasonics; Water