• Energy Research

Abstract Hydrothermal gasification of woody wastes, pine tree and fir tree sawdust, was performed in a batch autoclave at 500 and 600 °C and a pressure range of 20.0–42.5 MPa with or without a 10 wt.% of K2CO3. The products in the gaseous state (H2, CO2, and CH4, CO, and C2–C4 compounds) and in the aqueous state (carboxylic acids, furfurals, phenols, aldehydes, and ketones) were analyzed by gas chromatography and high performance liquid chromatography. The produced gas amount and the hydrogen and methane yields were found maximized at 600 °C with the addition of K2CO3. The decreasing pressure promoted hydrogen yields while decreasing the methane yields. The aqueous product was mainly composed of acetic acid, formic acid, and little amount of hydroxyacetic acid in the group of carboxylic acids and 5-methyl furfural and 5 hydroxymethyl furfural as furfurals. Supercritical water gasification of wood wastes is promising as a source in the production of hydrogen and methane.

In this study, levulinic acid is produced from Jerusalem artichoke (JA, Helianthus tuberosus L.) by hydrothermal decomposition reactions in a batch autoclave reactor. The parameters studied were reaction temperature (T, K), reaction time (t, min), starting material concentration (C), and pH of the aqueous HCl solution (pHinitial) using the Box-Behnken response surface methodology. The highest yield was 35.28% at 165 degrees C, 89.7 min, 0.5 pH, and 0.045 g/mL concentration within a 95% confidence interval. Dilute feedstock concentrations, low pH of the aqueous acid catalyst solution, and relatively high temperatures should be preferred to maximize the yield LA.Graphical AbstractFigure graphical abstract 1. The result of the response optimizer for LA within the studied operating conditionsFigure graphical abstract 1. Variation of organic acid and furfural content, in the liquid product over time at different reaction temperatures at 0.045 g/mL and pH = 1.0Figure graphical abstract 2. Variation in the yields of organic acid and furfural and sugar compounds in the liquid product over time at different reaction temperatures at 0.045 g/mL and pH = 1.0Graphical AbstractFigure graphical abstract 1. The result of the response optimizer for LA within the studied operating conditionsFigure graphical abstract 1. Variation of organic acid and furfural content, in the liquid product over time at different reaction temperatures at 0.045 g/mL and pH = 1.0Figure graphical abstract 2. Variation in the yields of organic acid and furfural and sugar compounds in the liquid product over time at different reaction temperatures at 0.045 g/mL and pH = 1.0Graphical AbstractFigure graphical abstract 1. The result of the response optimizer for LA within the studied operating conditionsFigure graphical abstract 1. Variation of organic acid and furfural content, in the liquid product over time at different reaction temperatures at 0.045 g/mL and pH = 1.0Figure graphical abstract 2. Variation in the yields of organic acid and furfural and sugar compounds in the liquid product over time at different reaction temperatures at 0.045 g/mL and pH = 1.0

Abstract Residues of leek, cabbage and cauliflower from the market places as representatives of lignocellulosic biomass were processed via hydrothermal gasification to produce energy fuel. The experiments were carried out in a batch reactor at temperatures 300, 400, 500 and 600 °C and corresponding pressures varying in the range of 7.5–43 MPa. Natural mineral additives trona, dolomite and borax were used as homogenous catalysts to determine their effects on the gasification. More than 70 wt% of carbon in vegetable residue samples were detected in the gas phase after the hydrothermal gasification process at 600 °C. The addition of trona mineral further promoted the gasification reactions and as a result, less than 5 wt% carbon remained in the solid residue at the same temperature, degrading the biomass samples into gas and liquid products. The fuel gas with the highest calorific value was recorded to be 25.6 MJ/Nm3, from the hydrothermal gasification of cabbage at 600 °C, when dolomite was used as the homogeneous catalyst. The liquid products obtained in the aqueous phase were detected as organic acids, aldehydes, ketones, furfurals and phenols. The gas products were consisted of hydrogen, carbon dioxide, methane, and as minors; carbon monoxide and low molecular weight hydrocarbons (ethane, propane, etc.). Above 500 °C, all biomass samples yielded 50–55 vol% of CH4 and H2 while the CO2 composition was around 40 vol% as the gas product.

The wastewater from an opium processing plant should meet the standards as specified in the ‘Water Pollution Control Regulation (WPCR), 2004’ before being discharged safely into the receiving medium. Treatment of opium alkaloid wastewater is not sufficient using the existing combined methods of aerobic/anaerobic and chemical treatment. Hydrothermal gasification (HTG) is proposed as an alternative treatment in this study. The other aim of this study is to show the ability to manufacture CH4 and H2 as renewable energy sources and to determine to what extent the removal of chemical oxygen demand (COD) is. Studies were carried out in batch autoclave reactor systems without catalyst, with original red mud (RM), activated RM, and nickel-impregnated (10, 20, and 30%) forms. Reduction with NaBH4 was done to the nickel-impregnated forms of RM to increase the catalytic activity. Yields of CH4 and H2 increased from 16.8 to 28.6 mol CH4/kg C in wastewater and from 20.3 to 33.3 mol H2/kg C in wastewater with 20% impregnated nickel and reduced red mud as the highest at 500 °C. The COD of the wastewater was lowered by 81–85% approximately while the TOC content decreased by 85–90%.

This work examined the hydrothermal breakdown of biomass to platform chemicals, including acetic acid (AA), formic acid (FA), 5-hydroxy methylfurfural (5-HMF), and levulinic acid (LA). Chicory was selected as feedstock bacause of high potential to produce . Reactions were performed with BSA (Benzenesulfonic acid) and LABSA (Linear alkyl benzene sulfonic acid) as sulfonic acid catalysts. The studies were conducted with different catalyst concentrations (100, 300, and 600 mM) for 110 minutes at 200 °C with a biomass to solvent ratio of 1g/25 mL. The variation of product yield and composition on parameters such as time, sulfonic acid concentration and type were investigated. The maximum levulinic acid yields (wt.%) achieved through the experiments of this study were 23.95 wt.% (9.58 g/L) for 600 mM BSA and 85.93 wt.% (34.37 g/L) for 600 mM LABSA at 200 °C. Highest carbon-based yields of levulinic acid were obtained with 300 mM LABSA and 100 mM BSA.

AbstractBACKGROUNDIncreased water demand caused by population growth has forced the reuse of wastewater after treatment. Safflower is a salt‐tolerant plant that can be irrigated with moderately saline water. Cultivation of safflower plant can be achieved by irrigation with membrane bioreactor (MBR)‐treated wastewater and further utilized in oil and then biodiesel production according to standard (TS EN 14214). Irrigation water quality can impact oil and biodiesel yield and content.RESULTSIn this study, safflower plants were cultivated using different irrigation strategies in a field next to a wastewater treatment plant in Menderes‐Izmir, Turkey. These strategies were: irrigation weekly with MBR‐treated wastewater or with tap water; with MBR‐treated wastewater just three times during phenological periods; and without irrigation. Oil yields for seeds of the plants irrigated by these strategies were 103.8, 98.7, 63.7 and 57.4 (kg oil daa−1), respectively. Oil yield was found to be highest following weekly irrigation with MBR‐treated wastewater that has a high salinity of 4 mS cm−1. Safflower oil methyl ester (SOME) contents of biodiesel were 94.6 and 94.5% (g SOME:g biodiesel), and ester yields of biodiesel were 71.3 and 81.4% (g biodiesel:g oil–1) for safflower irrigated weekly with MBR‐treated wastewater and tap water, respectively.CONCLUSIONIt is concluded that SOME yields and contents of safflowers irrigated with MBR‐treated wastewater and tap water weekly are so close. © 2019 Society of Chemical Industry

Safflower stalk is a suitable lignocellulosic biomass that can replace fossil resources for the production of platform chemicals. In this study, the production of levulinic acid (LA) from safflower stalk using aromatic sulfonic acids as environmentally friendly catalysts was investigated. A Taguchi experimental design was used to determine the conditions for the highest product yield. The variations of valuable by-products such as 5-HMF, formic acid, and acetic acid, which may occur depending on the reaction conditions were also analyzed. Optimum conditions for maximum LA yield were found using para-toluenesulfonic acid (PTSA) with concentration of 0.3 M, solvent/biomass ratio as 20 at a temperature of 200 degrees C. Experiments were also carried out to verify the optimum LA yield found using analysis of variance (ANOVA). Comparison experiments were performed with sulfuric acid (H2SO4) under optimum conditions, and it was concluded that PTSA could be an alternative catalyst to H2SO4 in terms of LA yield. This study was financed by the Ege University Scientific Research Fund under project number FDK-2019-20794. Ege University Scientific Research Fund [FDK-2019-20794]

Abstract Hydrogen as a clean energy source has great potential to reducing the dependence on fossil fuels and environmental pollution. For this reason, the production of hydrogen from renewable source will decrease this dependence and pollution. In this study, production of hydrogen from olive pomace was investigated. The experiments were performed at batch autoclave between 300 °C and 600 °C temperatures and a pressure of 200 atm–425 atm range. In addition to these parameters, the effect of catalyst (Trona, K2CO3 and KOH) was also investigated. H2, CO2, CH4, CO and small amount of C2 C4 hydrocarbons were identified in gaseous products. H2 formation increased with increasing temperature and decreased with pressure increase. Hydrogen formation has the highest value as 16.80 mol/kg biomass at 600 °C in the presence of KOH catalyst. Besides the effect of KOH, the presence of K2CO3 and Trona catalysts also increased the formation of hydrogen. The pressure affected the gasification yield and hydrogen composition in gaseous product.