maleic-acid and sulfuric-acid

The aim of this study was to investigate the effects of different acid catalysts and pretreatment factors on the hydrolysis of biomass compounds over a range of thermochemical pretreatments; maleic, oxalic, and sulfuric acids were each used under different pretreatment conditions. The most influential factor for fermentable sugar production in the dicarboxylic acid-pretreated mixed hardwood was pH. Reaction time was the next significant factor followed by reaction temperature. However, fermentable sugar production was more dependent on reaction temperature than time during sulfuric acid pretreatment, whereas the effect of acid concentration was considerably lower. Maleic acid pretreatment was very effective for attaining high glucose yields after enzymatic hydrolysis. The highest enzymatic hydrolysis yield was found following maleic acid pretreatment, which reached 95.56%. The trend in enzymatic hydrolysis yields that were detected concomitantly with pretreatment condition or type of acid catalyst was closely related to xylose production in the hydrolysate.

Topics: Biomass; Carbohydrates; Glucose; Hydrolysis; Maleates; Oxalic Acid; Quercus; Robinia; Sulfuric Acids; Wood; Xylose

The paper presents an on-line transient moving chemical reaction boundary (MCRB) method for simply but efficiently stacking analytes in capillary electrophoresis (CE). The CE technique was developed for a rapid determination of fumaric and maleic acid. Based on the theory of MCRB, Effects of several important factors such as the pH and concentration of running buffer and the conditions of stacking analytes were investigated to acquire the optimum conditions. The optimized separations were carried out in a 20 mmol/L sulphate neutralized with ethylenediamine to pH 6.0 electrolytes using a capillary coated with poly (diallyldimethylammonium chloride) and direct UV detection at 214 nm. The optimized preconcentrations were carried out in 50 mmol/L borax (pH 9.0). The calibration curves were linear in the concentration range of 1.0×10⁻⁷-1.0×10⁻⁴ mol/L and 5.0×10⁻⁷-1.0×10⁻⁴ mol/L for fumaric and maleic acid with correlation coefficients higher than 0.9991. The detection limits were 5.34×10⁻⁸ mol/L for fumaric acid and 1.92×10⁻⁷ mol/L for maleic acid. This method was applied for determination of fumaric acid in apple juice and of fumaric and maleic acid in dl-malic, the recovery tests established for real samples were within the range 95-105%. This work provided a valid and simple approach to detect fumaric and maleic acid.

Topics: Alkalies; Borates; Electrophoresis, Capillary; Ethylenediamines; Fumarates; Hydrogen-Ion Concentration; Linear Models; Maleates; Reproducibility of Results; Sensitivity and Specificity; Sulfuric Acids