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

Abstract Biomass is encouraged as a renewable energy source due to the energy crisis and the increase of greenhouse gases in the environment. Basic energy conversion methods, such as gasification and combustion, start with the devolatilization of organic molecules. In this study, the behavior of agricultural biomass from Turkey that contained various cellulose and lignin fractions was studied during slow pyrolysis and combustion. The pyrolysis of lignin produced the largest gas production, with CO2 constituting up the bulk of the gas mixture. CO is the second-highest-yield gas and is primarily formed from samples of cellulose and lignin. For lignin samples, the pyrolysis operation yielded the maximum amount of char, while the combustion of the lignin chars produced the highest amount of gas yields. On the other hand, lignin samples, particularly almond lignin, have the lowest tar production. One of the most significant issues with gasification is tar production and removal, and biomass rich in lignin would be the best material to use when tar formation must be kept to a minimum.

In addition to examining the highest yield production of Levulinic acid (LA) from artichoke leaves by the subcritical catalytic hydrothermal decomposition, the studies were carried out on also increasing the production yields of 5-Hydroxymethylfurfural (HMF), Acetic and Formic acid from this biomass. In order to obtain the most suitable reaction conditions, the effect of different reaction conditions, including different temperature, reaction time, pH and catalyst types, on the decomposition of artichoke leaves and product yields were investigated. The subcritical thermal decomposition studies of artichoke leaves were carried out in an autoclave system at temperatures (120°C, 140°C, 160°C, and 180°C) for reaction times of 10, 20, 30, 40, and 50 min in the presence of H2SO4, HNO3, and HCL catalysts with different pH values; these reactions were realized also without adding a catalyst. As a result of the detailed research, it was seen that the most suitable experimental conditions for the production of LA with the highest yield from artichoke leaves could be achieved by adding sulfuric acid with a pH of 0.5 at a reaction temperature of 180°C and a reaction time of 50 min. The investigations were continued till achieving the highest product yields. After carrying out the experiments stated above, the optimal yields of the products produced from the artichoke biomass by the reactions were found as 209.39 g/kg biomass for LA, 117.40 g/kg biomass for formic acid, 72.27 g/kg biomass for acetic acid, and 39.04 g/kg biomass for 5-HMF.

In this study, the devolatilization behavior of eastern Mediterranean hazelnut, almond, and sunflower residue was studied using a TGA–FTIR laboratory-scale setup. The original biomasses were fractionated using the Van Soest detergent analysis. Both the original and fractionated biomasses were investigated. The reaction temperature was increased to 900 °C using a heating rate of 2 °Cmin−1. The pyrolysis of lignin produced the largest gas production, with CO2 constituting up the bulk of the gas mixture. CO is the second highest-yield gas and is primarily formed from the samples of cellulose and lignin. For the lignin samples, the pyrolysis operation yielded the maximum amount of char, while the combustion of the lignin chars produced the highest amount of gas yields. On the other hand, lignin samples, particularly almond lignin, have the lowest tar production. Due to the high ash content the sunflower stalk sample devolatilized at a lower temperature with respect to the rest of the samples, resulting at a mass loss peak at lower temperature. The hazelnut lignin showed the mass loss peak at the highest temperature. Generally, CO2 showed the highest mass yield, and it was mainly produced from the cellulose and whole biomass samples. Among all samples CH4 was produced in minor quantities and mostly in lignin devolatilization. Furthermore, the devolatilization behavior of the fractionated biopolymers is not enough to sufficiently predict the behavior of the whole biomass sample. The results described in this paper can help further the understanding of thermal processes where almond, hazelnut, and sunflower residues from the eastern Mediterranean region, and their fractionated-derived products are involved.

Water hyacinth (Eichhornia crassipes) was anaerobically digested with waste sludge in a batch system at varying total solid (TS) contents (3.3-8.3%) and temperatures (35-55 degrees C). Then, the high organic content of digested biomass was utilized for hydrothermal liquefaction/gasification in the batch reactor system at different temperatures (200-600 degrees C) to yield biofuels and biochemicals. Hydrothermal liquefaction/gasification was performed in sub-and super-critical water (above 374 degrees C and 221 bar) conditions. Prevailing products are some biochemical compounds (carboxylic acids, furfurals, aldehyde/ketones, phenols etc.) at lower temperatures (200-300 degrees C) while biohythane (total of hydrogen and methane) gaseous fuel are produced at higher temperatures (400-600 degrees C). The highest carbon gasification efficiency (73 g C in product/g C in feed) was obtained at 600 degrees C with the sample that has a high anaerobic digestion efficiency (digested at 6.3 TS% at 35 degrees C). The highest carbon liquefaction efficiency (37.2 g C in product/g C in feed) was obtained at 200 degrees C with the sample which has a low anaerobic digestion yield (digested at 8.3 TS% at 35 degrees C).(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Lignocellulosic biomass is accepted to be one of the best sustainable alternatives for overcoming fossil fuel dependence and to reduce environmental pollution. Intensive research studies have been carried out on conversion of this big potential source via chemical and biochemical processes to miscellaneous chemicals. According to one of the present methods of chemical conversion, cellulose and hemicellulose parts of the plant biomass can be converted to platform chemicals by hydrolysis, dehydration and rehydration reactions in the presence of acidic medium. In this study, the efficient conversion conditions of the Artichoke (Cynara Scolymus L.) leaves and stalks to the valuable chemicals (formic acid, acetic acid and 5-hydroxymetilfurfural) were investigated using acid (HCl, HNO3 and H2SO4) catalyzed hydrothermal reaction. Experiments were performed in the temperature range of 150°C - 300°C and at the pH values 2.0 - 3.0 with a reaction time of 1 hour. Evolution of liquid parts and their variations with respect to reaction parameters were determined using HPLC via related analysis

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 °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.

The compost produced from organic wastes (MSW, city market’s wastes and wood dust) was selected to be processed via supercritical water gasification (SCWG) in order to produce gas product consisting of hydrogen and methane mainly. The effects of parameters such as temperature, reaction time and KOH as an additive were determined and around 55 vol.% of H2 and CH4 in the gas product was found after 30 min reaction time together with KOH, at 500 oC. The red mud catalysts did not improve the gasification yields even though they increased the calorific value of the product gas.

Hydrothermal gasification of tomato processing plant waste was examined in batch autoclaves at temperatures of 300-600 C and pressures of 20.0-42.5 MPa. The catalytic effects of KOH and K2CO3 at the aforementioned temperatures and pressures were also investigated. While increasing the pressure enhanced methane yield, alkali addition improved both hydrogen and methane yields. The highest yields for H2 and CH4 were recorded as 27.4 and 21.8 moles kg-1 C at 600 C and with KOH. In addition, carbon gasification efficiency (CGE) obtained was up to 86% while carbon liquefaction efficiency (CLE) was reduced to 3.5% with KOH at 600 C and 20 MPa. A product gas with a calorific value of 24.9 MJ/Nm3 was obtained during hydrothermal gasification at 500 C and 42.5 MPa, in the presence of KOH.

Dehydration of glucose was investigated over natural vermicompost derived biochar-based catalysts at 140 oC. Biochar was produced via hydrothermal processing and selected biochar was further calcinated to improve catalytic activity. Effects of hydrothermal treatment and calcination temperature on glucose conversion and product distribution were investigated. Reaction parameters such as reaction temperature and time were also optimized with the catalyst supplying best catalytic performance. While increase in the hydrothermal treatment temperature reduced the conversion slightly but not affected the product distribution, calcinating the VC-220 catalyst improved the catalytic activity. Half of the total products were due to fructose isomerization and the second large share among the products was gluconic acid. It was formed via glucose oxidation by the redox sites in the biochar-based catalysts. Increase in the reaction temperature (from 140 to 170 oC) enhanced the catalytic activity as expected. On the other hand, reaction route was directed to the dehydration and oxidation instead of the isomerization. Glucose conversion was linearly increased with reaction time. Transition from isomerization to dehydration-oxidation with reaction time was also observed.

Supercritical water gasification (SCWG) is a promising waste treatment technology for streams from wine industry, which can eliminate its pollution and produce biofuels simultaneously. In this study, we investigated the influence of catalyst concentration and temperature for efficient SCWG so as to shift the product distribution toward more desirable compounds. Also, experiments have been demonstrated to examine the effect of the group 1A carbonates (Li2CO3, Na2CO3, K2CO3, and Cs2CO3). Wine industry wastes have been successfully gasified and the products were identified by using chromatographic methods. As going down from top to bottom in group 1A by increasing reaction temperature, the highest H2 and CH4 yields were obtained with Cs2CO3 at 600 degrees C. These results support the development of the reaction conditions by effective catalysts to contribute to the solution of the global bioenergy shortage and effective waste management of the industry.

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 degrees 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 degrees 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/Nm(3), from the hydrothermal gasification of cabbage at 600 degrees C, when dolomite was used as the ho-mogeneous 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 degrees C, all biomass samples yielded 50-55 vol% of CH4 and H-2 while the CO2 composition was around 40 vol% as the gas product. (C) 2020 Energy Institute. Published by Elsevier Ltd. All rights reserved.

BACKGROUND Increased 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. RESULTS In 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. CONCLUSION It is concluded that SOME yields and contents of safflowers irrigated with MBR-treated wastewater and tap water weekly are so close. (c) 2019 Society of Chemical Industry

The pyrolysis behavior of Turkish biomass samples such as hazelnut shell, almond shell, and sunflower stalk residue was studied using a thermogravimetric analysis (TGA) laboratory-scale setup. Biomass samples were characterized using the standard method of the Van Soest detergent analysis, and both the virgin biomass and fractions were investigated. The reaction temperature was increased to 900 °C with a heating rate range between 2 and 60 °C min−1 in the TGA experiments. Seven solid-state reaction models were applied to evaluate the obtained experimental TGA results. The heating rate was not the only parameter affecting the values of activation energy and the ratio of the main components such as the cellulose and lignin of the virgin biomass samples (almond shell, sunflower stalk, and hazelnut shell) also affected the value of the activated energy values. It was determined that a model fitting mechanism gives limited information to determine the exact activation energy values for the samples. The reaction order model provided straightforward and decisive results for all the biomass and lignin samples. Models of two- and three-dimensional diffusion were better suitable for the cellulose devolatilization. It was also determined that the activation energy of the lignin samples was similar regardless of the types of biomass. According to the kinetic calculations, the cellulose samples showed the highest activation energy values and the lignin samples had the lowest.

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%.

Hydrothermal gasification of isolated hemicellulose from the white poplar (Populus alba L.) and white poplar sawdust were studied to evaluate the effects of temperature (in the range of 300-600 degrees C) and the catalyst on the yield of the products. Hydrothermal gasification of poplar sawdust represents a future alternative to the waste management of agricultural residues, and industry waste. Hydrothermal gasification of isolated hemicellulose was helpful to understand and analyze the catalytic gasification characteristics of natural biomass material with high hemicellulose composition. The results indicated that hemicellulose isolated from poplar produced more gaseous products than poplar sawdust. The hemicellulose isolated from poplar wood left lower amount of ingasified solid residue than the biomass studied. Also yields of xylose, which is commercially available as hemicellulosic fraction and was studied in our previous study, was compared with isolated hemicellulose and real biomass. Among them, isolated hemicellulose had the highest yield in gasification. (C) 2020 Elsevier B.V. All rights reserved.

Activated sludge produced from biological treatment of textile and leather industrial wastewater was processed using hydrothermal gasification in order to produce fuel gas with high calorific value. The gasification experiments were performed in a batch reactor and the effect of temperature (400, 450, 500 and 550 degrees C), additives (KOH and dolomite) and reaction time (0, 30 and 60 min) was investigated. The gas yield increased with the increasing temperature. Hydrogen and methane compositions in the gas was between 42 to 57 vol%, while CO2 was between 30 and 40 vol%. The calorific value of the sludge was determined as around 16 MJ/kg, while after gasification the calorific value of the gas fuel produced was found to be 24.7 MJ/kg (24.3 MJ/Nm(3)) after 30 min. reaction time in the presence of KOH. The addition of dolomite did not affect the gas yield however, addition of KOH promoted the water-gas shift reaction and boosted hydrogen yield in the product gas. Around 70 wt. % of the sludge was converted into either gas or liquid with hydrothermal treatment.

In this study, poplar wood chips were gasified in sub-and supercritical water as biomass feedstock. Hydrothermal gasification experiments were performed to examine how the reaction temperature and different type of catalysts influence conversion efficiency. The effectiveness of commercially available [alkali catalyst; KOH], naturally available [mineral catalysts; Trona [Na-3(CO3)(HCO3)center dot 2H(2)O], Dolomite [CaMg(CO3)(2)] and Borax [Na2B4O7 center dot 10H(2)O] and laboratory-prepared catalysts [metal-impregnated activated carbons; (Ni/AC) and (Ru/AC)] have been demonstrated so as to shift the product distribution toward more desirable compounds. Gaseous compound yield was increased from 29.7% to 79.3% with respect to increasing temperature while liquid compound yield decreased from 27.6% to 1.1% and solid residue from 38.0% to 15.6%. The highest H-2 (20.1 mol/kg C in poplar) and CH4 (12.7 mol/kg C in poplar) yields were obtained with Ru/AC catalyst. Carboxylic acids and 5-methyl furfural were determined as the main liquid compounds. (C) 2019 Elsevier B.V. All rights reserved.