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

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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.

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 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%.

Aspir ( Carthamus tinctorius ) yenilebilir yag uretiminde kullanilan yagli tohum bitkilerinden biri olup, yetistiriciligi son yillarda dunya genelinde artmaktadir. Yapilan calismalar aspir tohumu yaginin zeytinyagi, aycicegi ve yer fistigi yagi ile benzer ozellikler tasidigini gostermektedir. Aspir bitkisi tuzluluga ve soguk hava kosullarina toleransli olmasi sebebiyle kurak ve yari-kurak bolgelerde yetistirilebilmektedir. Aspir yaginin yuksek linoleik asit icerigi (%63-75) yemeklik yag acisindan onemli bir kalite ozelligidir. Bu ozellikleri ile bitkisel yag aciginin kapatilmasinda alternatif bir kaynaktir. Bu calismada aritilmis atiksu kullanilarak yetistirilen aspir bitkilerinin tohumlarindan elde edilen yagin kalite ve fizikokimyasal ozellikleri belirlenmistir. Yemeklik yag olarak kullanimi icin, Turk Gida Kodeksinde yer alan yag kalitesi standartlari ile kiyaslama yapilmistir. Aspir tohumlarindan yag uretimi, cozgen olarak n-hekzan kullanilarak Soxhlet ekstraksiyon yontemiyle gerceklestirilmistir. Elde edilen aspir yaglarina kalite ve fizikokimyasal yag analizleri uygulanmistir. Yag asidi ve sterol kompozisyonu, asitlik ve peroksit degeri, yogunluk, kirilma indeksi, iyot ve sabunlasma degerleri belirlenmistir.

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 degrees C and 600 degrees 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. H-2, CO2, CH4, CO and small amount of C-2-C-4 hydrocarbons were identified in gaseous products. H-2 formation increased with increasing temperature and decreased with pressure increase. Hydrogen formation has the highest value as 16.80 mol/kg biomass at 600 degrees 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. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

The hydrothermal gasification of opium alkaloid wastewater was investigated in a batch autoclave at 400, 500, and 600 degrees C at a pressure range of 23.0-45.5 MPa without and with various amount of K2CO3 catalyst. The maximum gas yields, hydrogen and methane, were obtained at 600 degrees C using K2CO3 at amounts higher than 0.375 g. TOC and COD contents of the aqueous products and raw wastewater were analyzed, the compounds existing in the raw wastewater and the aqueous products were identified and compared. The wastewater used in this work has a COD content of 35,000 mg O-2/L and a TOC content of 15,000 mg/L and the highest COD removal efficiencies acquired was 95% at 600 degrees C and in the presence of K2CO3 (varying from 0.375-0.625 g). The H-2 and CH4 yields were maximized at 47.7 and 34.3 mol/kg OC in wastewater using 0.5 g of K2CO3 and at 600 degrees C, respectively.

ABSTRACT: The wastewater coming from the alkaloid production plant installed in our province Afyon, must satisfy the discharge limits specified in “Water Pollution Control Regulations, 2004” to discharge safely to the receiving environment. Treatment of alkaloid plant wastewater by the existing treatment method which is a combination of the biological (aerobic / anaerobic) and chemical treatment is not sufficient. In this study, hydrothermal gasification (or supercritical water gasification, SCWG) is proposed as an alternative and advanced treatment technique. The other objectives of the study is to show the producibility of methane and hydrogen as renewable energy source and to investigate , to investigate what extent removal of chemical oxygen demand and polluting compounds as a spontaneous result of gasification. The effect of catalyst in the highest conversion of organic carbon content in wastewater to the gaseous product rich in H 2 ve CH 4 , the maximum efficiencies in TOC and COD removals. Hydrothermal gasification studies of alkaloid wastewater were carried out without catalyst and with Na 2 CO 3 (N). The experiments were performed at the reaction temperatures of 400, 500 and 600°C with/without 0.12 g of catalyst and 15 ml of wastewater. The gaseous products were analysed in gas chromatography, the TOC and COD content of the aqueous products and raw wastewater were analysed in TOC analyser and COD analysis set. The variation of the product distribution and yields, TOC and COD removal by temperature and catalysis were examined. The initial TOC, and COD values of the wastewater studied were 15.000 mg/L and 35.000 mg/L.

Hydrothermal decomposition of mannose (8 wt.%) in near- and super-critical water was investigated at 500-700 degrees C and 20.0-42.5 MPa with a reaction time of 1 h in the absence and presence of alkali catalyst (K2CO3). Gaseous products, aqueous products, and residue were observed in the batch reactor. The produced gases were carbon dioxide, methane, hydrogen, carbon monoxide, and C-2-C-4 hydrocarbons. The effect of operating parameters (temperature and pressure) on the product distribution was examined in the absence and presence of potassium carbonate. The gaseous product yields were compared with the theoretical equilibrium values that are estimated by Gibbs free energy minimization. In the absence of catalyst, the hydrogen yield was 5.82 mol H-2/mol mannose at 700 degrees C and 20.0 MPa. At this condition, theoretical equilibrium yield of hydrogen was found as 5.78 mol H-2/mol mannose which was very close to the experimental value and addition of K3CO3 increased the hydrogen yield to 10.34 mol H-2/mol mannose. The hydrogen yield increased with increasing temperature and decreasing pressure. Acetic acid was the major component of the aqueous product in gasification of mannose. (C) 2015 Elsevier B.V. All rights reserved.

Energy from biomass can be provided in various ways, such as burning the solid wastes, production of biogas (by anaerobic digesters), biofuels (i.e. methanol, ethanol, biodiesel, and derivatives), and methane via the utilization of landfills. Biodiesel is a widely used biofuel produced by the conversion of first-generation biomass feedstock via bio-chemical conversion platforms.Crude glycerol is the by-product of biodiesel production being 10 wt.% of the produced biodiesel. The objective of this study is to utilize this glycerol fraction by converting it to fuel gas or to chemical feedstock.In this study, the concentration of glycerol feedstock solution and the catalyst concentration were 50 g/L and 5 g/L, respectively. Crude glycerol was gasified in a sub and supercritical water medium by using a batch autoclave with an inner volume of 100 ml. A temperature range from 300 to 600 degrees C was studied. Experiments were performed with pure and crude glycerol samples in the absence and the presence of homogeneous acidic and alkali catalysts, namely H3PO4, KH2PO4, K2HPO4, and K3PO4. These were used to obtain higher gasification efficiencies and hydrogen and/or methane yields.Subsequent to each experiment liquid, solid, and gaseous products were collected and analyzed by GC, TCA (total carbon analyzer), HPLC, and GC/MS.The order of the effectiveness of the catalysts on gasification was found as: K3PO4 > K2HPO4 > H3PO4 > KH2PO4 for crude glycerol and K3PO4 > K2HPO4 > KH2PO4 > H3PO4 for pure glycerol. K2HPO4 and K3PO4 were found to be more effective in terms of hydrogen production while H3PO4 and KH2PO4 showed the best performance for the maximized methane production. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Hydrothermal gasification of woody wastes, pine tree and fir tree sawdust, was performed in a batch autoclave at 500 and 600 degrees 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 (H-2, CO2, and CH4, CO, and C-2-C-4 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 degrees 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. (C) 2015 Elsevier B.V. All rights reserved.

In this study, production possibilities of hydrogen and/or methane via SCWG from black grape residues have been investigated. For this aim, grape residues which remain as a byproduct of the wine making process have been used. Since utilization from grape residues is limited due to the high moisture content, supercritical water gasification is the most convenient method. The effect of the gasification temperature and type of catalyst on supercritical water gasification have been investigated. Gasification experiments were performed in a batch autoclave at four different temperatures 300, 400, 500 and 600°C. K2CO3 and Trona (NaHCO3.Na2CO3·2H2O) were used as catalyst. Real biomass types of black grape residues have been successfully gasified and the product gas (hydrogen, methane, carbon dioxide, carbon monoxide and a small amount of ethane and ethylene) were identified by using gas chromatography. A TOC analyzer was used to determine total organic carbon (TOC) content of aqueous phase. The amounts of carboxylic acids, aldehydes, ketones, furfurals and phenols present in the aqueous solutions were analyzed by high performance liquid chromatography. When the temperature increased from 300°C to 600°C, mol% of H2 in gas products increased. The presence of catalysts improves the hydrogen yield. Trona showed gasification activity to be similar to that of K2CO3. It may be concluded that the use of Trona instead of commercially produced catalysts, can be preferably used in the gasification of biomass in supercritical water. Keywords—Biomass, hydrogen, grape residues.

Hydrogen and methane are drawn attention due to their potential of using as clean energy sources recently. Production of these valuable gases by hydrothermal gasification (supercritical water gasification) from the biomasses is of interest and novel technology. In this technique, organic part of the lignocellulosic biomasses is converted into gaseous products substantially above the critical temperature and pressure of water (374 o C, 221 atm). The most significant advantage of the method is to be able to gasify the wet biomass materials without the need for drying. Lignocellulosic biomasses mainly consist of cellulose, lignin, hemicelluloses and extractive parts. They show different attitude in hydrothermal gasification. Significant varieties are observed in the gasification yields and product distributions of these parts. In recent years, intensive studies have being done using cellulose, lignin and model compounds forming them. There is not enough work carried out with the hemicelluloses which are being approximately 1/3 of a plant, and this is a significant deficiency in the literature. The experiments were carried out in the set up of hydrothermal gasification with reactor inner volume of 100 cm 3 . The corn-cob hemicellulose was used as feedstock. The effect of the reaction temperature (300, 400, 500 and 600°C) and the catalysts (K 2 CO 3 and KOH) were investigated to reach maximum mol of H 2 and CH 4 . Carbon gasification efficiency (CGE; g C in gaseous /g C in biomass), carbon liquefaction efficiency, (CLE; g C in aqueous /g C in biomass), and residue efficiency, (RE; g C in residue /g C in biomass) were given in Fig.1, the composition and amount of the products were identified with the analyses by GC, GC-MS, HPLC, TOC, SSM and the colorimeter. Gas product compositions were shown in Fig. 2. Main gaseous products were CO 2 , H 2 , CH4, small amount of CO and C 2 -C 4 hydrocarbons. In aqueous product, there were lots of organic substances such as carboxylic acids, alcohols, aldehydes, ketones, furfurals and phenols. The highest yields were obtained in hydroxy acetic acid, formic acid, acetic acid, 5MF and phenol mostly. Maximum gas conversion, highest H 2 and CH 4 yields were reached at 600°C and in the presence of catalyst. As the reaction temperature increased, CGE, H 2 and CH 4 yields increased while CLE and RE were decreased. K 2 CO 3 and KOH improvement ratios on the gasification efficiency were found as 11.3% and 11.6%, respectively. H 2 , CH 4 yields were increased 30.8% and 34.4% in the presence of K 2 CO 3 ; 32.3% and 33.3% in the presence of KOH, respectively.