Digestibility Improvement of Sorted Waste with Alkaline Hydrothermal Pretreatment

The digestibility of sorted municipal solid waste （MSW） is often limited by the high content of structured green waste. The objectives of this study are to investigate the effect of alkaline hydrothermal pretreatment on the anaerobic digestion of sorted waste and to analyze the biogas production of different parts of the waste. The waste was hydrothermally pretreated in a dilute alkali solution. The hydrolysis product was then incubated in a 500 mL saline bottle to determine the biochemical methane potential （BMP） under mesophilic anaerobic conditions. The optimum hydrothermal condition was 170℃ at 4 g NaOH/100 g solid for one hour. The concentration of chemical oxygen demand （COD） was 13 936 mg/L and the methane yield was 164 mL/g volatile solid （VS） for 6 days incubation at the optimum conditions. The biogas production was increased more than 50% over the control, with the methane conversion ratio on a carbon basis enhanced to 30.6%. The organic part of the sorted waste was mainly kitchen garbage and leaves. Model kitchen garbage completely liquified at 130℃ for one hour had a methane yield of 276 mL/g VS. The alkali addition slightly enhanced the hydrolyzation rate and methane yield. The biogas potential of leaves was improved by pretreatment at above 150℃ under alkaline conditions.

Highly efficient preparation of 5-hydroxymethylfurfural from sucrose using ionic liquids and heteropolyacid catalysts in dimethyl sulfoxide–water mixed solvent

Several types of ILs and solid acids were used as catalysts in one-pot conversion of sucrose to 5-hydroxymethylfurfural（abbreviated as 5-HMF） in a dimethyl sulfoxide（DMSO）/water mixed solvent under hydrothermal conditions. A remarkable 5-HMF yield of 91.8% was achieved catalyzed by the cesium salt of dodecatungstophosphoric acid（Cs（2.3）H（0.7）PW（12）O（40）） within 3 h at 180 C. The ionic liquid N-methylimidazolium hydrogen sulfate（[Hmim][HSO4]） gave the 5-HMF in 82.0% yield from sucrose. To the best of our knowledge, it was almost the highest yield of HMF from sucrose by now. Various reaction parameters including reaction temperature and time and catalyst dosage were optimized. A possible mechanism for this catalytic process was proposed. Furthermore, fructose and glucose were also investigated, good yields of 5-HMF was obtained respectively. This increases the possibility of large-scale production of 5-HMF from carbohydrates.