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Öğe A critical review of pretreatment technologies to enhance anaerobic digestion and energy recovery(Elsevier Sci Ltd, 2020) Atelge, M. R.; Atabani, A. E.; Banu, J. Rajesh; Krisa, David; Kaya, M.; Eskicioglu, Cigdem; Kumar, GopalakrishnanBiogas production from different waste resources still has limitations due to its complex structure and slowly biodegradable nature. To improve methane yield and anaerobic digestion performance, various substrate pretreatment methods have been suggested. This paper reviews the latest trends, progress, and research achievements about pretreatment technologies to improve anaerobic digestion efficiency. The pretreatment techniques are divided into four main groups which are physical, chemical, biological, and combined. The effect of inhibitor formation during the pretreatment process is discussed. The energy performance, economics, and environmental impact of these pretreatment technologies are revealed. This study concludes with future trends and emphasizes the necessity of pretreatment methods.Öğe A dual functional material: Spirulina Platensis waste-supported Pd-Co catalyst as a novel promising supercapacitor electrode(Elsevier Sci Ltd, 2021) Karakas, Duygu Elma; Akdemir, Murat; Atabani, A. E.; Kaya, MustafaIn the present study, Spirulina Platensis waste-supported Pd-Co (SPW-Pd-Co) catalyst was used as an efficient catalyst for the methanolysis reaction of sodium borohydride (NaBH4); moreover, the produced SPW-Pd-Co catalyst was tested as a supercapacitor electrode material for the first time. In this context, the SPW-Pd-Co catalyst was synthesized by the treatment of the Spirulina Platensis waste (SPW) with 1-7 M HCl, 1 mL PdCl2 solution (2% w/w) and 1, 2, 3, 4, and 5 mL CoCl2 center dot 6H(2)O solution (5% w/w). Under optimum conditions, the most active catalyst was obtained by burning with 3 M HCl-Pd-4 mL Co2+ solution at 600 degrees C for 90 min. The maximum rate of hydrogen generation (HGR) obtained at 30 degrees C from the NaBH4 methanolysis reaction was found to be 5497.7 mLmin(-1) gcat(-1), and the catalyst activation energy was found to be 10.32 kJ mol(-1). The gravimetric capacitance of the prepared electrode was calculated as 50 F/g at 2 A/g current density. The capacitance values of the supercapacitor are at a significant level in terms of capacity and the cost.Öğe A novel Microcystis aeruginosa supported manganese catalyst for hydrogen generation through methanolysis of sodium borohydride(Pergamon-Elsevier Science Ltd, 2020) Duman, Fatih; Atelge, M. R.; Kaya, Mustafa; Atabani, A. E.; Kumar, Gopalakrishnan; Sahin, U.; Unalan, S.In this study, Microcystis Aeruginosa (MA)- microalgae species was used for the first time as a support material with metal ions loading to fabricate a highly efficient catalyst for the hydrogen generation through methanolysis of sodium borohydride (NaBH4). Microalgae was pre-treated with hydrochloric acid (3 M HCl) for 24 h at 80 degrees C. Subsequently, different metal ions (Mn, Co, and Mo) were loaded to the pre-treated samples. Finally, metal-loaded samples were subjected to burning in oven to fabricate the catalyst. Primarily, manganese metal was selected based on the best metal performance. Afterwards, different metal loading ratios, burning temperatures and burning times were evaluated to synthesize the optimal MA-HCl-Mn catalyst. Results showed the optimal conditions as Mn ratio, burning temperature and time as 50%, 500 degrees C and 45 min, respectively. To characterize the catalyst, FTIR, SEM-EDX, XRD, XPS and TEM analyses were performed. Hydrogen generation via methanolysis was performed at various NaBH4 ratio of 1-7.5% while changing concentrations from 0.05 to 0.25 g catalysts with diverge temperatures of (30, 40, 50 and 60 degrees C). The maximum hydrogen generation rate (HGR) by this novel catalyst was found as 4335.3, 5949.9, 7649.4 and 8758.9 mLmin(-1)gcat(-1), respectively. Furthermore, the activation energy was determined to be 8.46 kJ mol(-1). (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe A state-of-the-art review on spent coffee ground (SCG) pyrolysis for future biorefinery(Pergamon-Elsevier Science Ltd, 2022) Atabani, A. E.; Ali, Imtiaz; Naqvi, Salman Raza; Badruddin, Irfan Anjum; Aslam, Muhammad; Mahmoud, Eyas; Almomani, FaresCoffee is a globally consumed beverage that produces a substantial amount of valuable organic waste known as spent coffee grounds (SCG). Although SCG is a non-edible biomass, research initiatives focused on valorizing/ utilizing its organic content, protecting the environment, and reducing the high oxygen demand required for its natural degradation. The integration with biorefinery in general and with pyrolysis process in specific is considerered the most successful solid waste management strategy of SCG that produce energy and high-value products. This paper aims at providing a quantitative analysis and discussion of research work done over the last 20 years on SCG as a feedstock in the circular bioeconomy (CBE). Management stratigies of SCG have been thoroughly reviewed and pyrolysis process has been explored as a novel technology in CBE. Results revealed that explored articles belong to Chemical, physical., biological and environmental science branches, with Energy & Fuels as the most reporting themes. Published works correlate SCG to renewable energy, biofuel, and bio-oil, with pyrolysis as a potential valorization approach. Literature review showed that only one study focused on the pyrolysis of defatted spent coffee grounds (DSCG). The insightful conclusions of this paper could assist in proposing several paths to more economically valorization of SCG through biorefinery, where extracted oil can be converted to biofuels or value-added goods. It was highlighted the importance of focusing on the coupling of SCG with CBE as solid waste managment strategy.Öğe Anaerobic co-digestion of oil-extracted spent coffee grounds with various wastes: Experimental and kinetic modeling studies(Elsevier Sci Ltd, 2021) Atelge, M. R.; Atabani, A. E.; Abut, Serdar; Kaya, M.; Eskicioglu, Cigdem; Semaan, Georgeio; Lee, ChangsooThe effect of oil extraction from spent coffee grounds as a pre-treatment strategy prior to anaerobic digestion besides assessing the feasibility of defatted spent coffee grounds co-digestion with spent tea waste, glycerin, and macroalgae were examined. Mesophilic BMP tests were performed using defatted spent coffee grounds alongside four co-substrates in the ratio of 25, 50, and 75%, respectively. The highest methane yield was obtained with the mono-digestion of defatted spent coffee grounds with 336 +/- 7 mL CH4/g VS and the yield increased with the increase in the mass ratio of defatted spent coffee grounds during co-digestion. Moreover, defatted spent coffee grounds showed the highest VS and TS removal at 35.5% and 32.1%, respectively and decreased thereafter. Finally, a linear regression model for the interaction effects between substrates was demonstrated and showed that distinctly mixing defatted spent coffee grounds, spent coffee grounds, and spent tea waste outperforms other triple mixed substrates.Öğe Carbon molecular sieve production from defatted spent coffee ground using ZnCl2 and benzene for gas purification(Elsevier Sci Ltd, 2020) Kaya, M.; Atelge, M. R.; Bekirogullari, M.; Eskicioglu, Cigdem; Atabani, A. E.; Kumar, Gopalakrishnan; Yildiz, Y. S.The aim of the current study is to manufacture molecular sieve from the defatted spent coffee ground. The defatted spent coffee ground for the specified particle size (100 mu m) was chemically activated with different agents (ZnCl2, H3PO4, KOH) and then carbonized at different temperatures (400-900 degrees C). A thorough characterization of the produced activated carbon was performed and activated carbons with the highest BET surface area were subsequently used to produce carbon molecular sieve. The surface modification was performed with benzene vapor at different temperatures (600-900 degrees C) and different combustion times (30-90 min.). In addition to the BET analysis, SEM, TGA and FT-IR analysis were also undertaken. The results obtained through characterizations showed that the pore diameters of carbon molecular sieve produced from defatted spent coffee ground varied from 2 to 4 angstrom. To conclude, the results suggest that the fabricated carbon molecular sieve can be used for the removal of impurities such as CH4, CO2, NOx and other impurities in natural and biogas considering the porosity of the sieves.Öğe Co-digestion of vegetable peel with cow dung without external inoculum for biogas production: Experimental and a new modelling test in a batch mode(Elsevier Sci Ltd, 2021) Lahbab, Abderrahmane; Djaafri, Mohammed; Kalloum, Slimane; Benatiallah, Ali; Atelge, M. R.; Atabani, A. E.This paper examined both experimental and a new modelling test for biogas production based on Co-Digestion Ratio (CDR) of vegetable peel (VP) with cow dung (CD) without external inoculum. For this, vegetable peel was used as a substrate and cow dung was used as a co-substrate. Reactors in triplicate were prepared. The vegetable peel concentrations were 12, 8, 6 and 4 g VS/l with the same cow dung concentration (4 g of VS/l) which corresponds to a CDR of 3:1, 2:1, 1.5:1 and 1:1. A new mathematical model corresponding to the biotech anaerobic digestion process based only on the (CDR) and (VS) was implemented under Matlab Simulink. The experimental results indicate that the optimal cumulative methane production (CMP) of 2000 ml was generated in the reactor containing a (CDR) of 3:1 which corresponds to a methane yield of 170 ml CH4/ g VS. i.e., an improvement between 23 and 26% comparing to all other CDRs. The experimental results were conformed by the new mathematical model. After applying the invented new idea by converting the constants (Rm, L and Gm) into functions (Rm =f1 (CDR), L=f2(CDR) and Gm = f3 (VS)) and relating them to each other using the Gompertz relation. The new model was able to predict the methane produced using only two inputs: VS and CDR. While in the literature studies, which were used Gompertz relationship for kinetic modelling, the constants must be recalculated each time as a new model, although the substrates used are the same, only the composition is different. Analysis of the variance (ANOVA) between the experimental and modelling results showed that there is no statistically significant difference, with a significance level of 0.05. Finally, the invented new idea can be a key to another different research that uses the same substrate.Öğe Comparative investigation of multi-walled carbon nanotube modified diesel fuel and biogas in dual fuel mode on combustion, performance, and emission characteristics(Elsevier Sci Ltd, 2022) Atelge, M. R.; Arslan, Esenay; Krisa, David; Al-Samaraae, R. R.; Abut, Serdar; unalan, Sebahattin; Atabani, A. E.Biogas has been investigated as an alternative biofuel in dual fuel operating mode in a direct injection diesel engine. However, there is not sufficient information about using modified fuels with biogas. This study aimed to investigate the effects of modified diesel fuel and biogas on combustion behavior, performance, and emissions characteristics at 1500 rpm constant speed with 5 different load conditions at an interval of 25%. Diesel was modified with multi-walled carbon nanotubes with 30, 60, and 90 ppm. Diesel fuel and three modified fuels were used as pilot fuel and biogas was introduced through the intake manifold with the flow rate of 500 g/h as the primary fuel. Diesel mode fuels were denominated F1 while dual fuel mode fuels were labeled as F2, and the concentration levels were given subscript such as F2 (@60ppm). The experimental study revealed that modified fuel showed better combustion behaviors, performance, and emissions in comparison to diesel fuel. Further, the same trend was observed in the dual fuel mode. The maximum pressure of F2(@60 ppm) was 1% higher than F2 under dual fuel mode at the full load. Moreover, the coefficient of variation of the indicated mean effective pressure for dual fuel mode was found approximately 9.2, 6.9, 6.2, and 7.2% for F2, F2(@30 ppm), F2(@60 ppm), and F2(@90 ppm), respectively at full load. In addition, the energy share of biogas increased by 7.9, 8.7, and 7.1% for F2(@30 ppm), F2(@60 ppm), and F2(@90 ppm), respectively in comparison with F2 at full load. The highest decrease of brake specific energy consumption under the dual mode was obtained to be an 8% drop from F2(@60 ppm) compared to F2 at full load. At the same load, the brake thermal efficiency of F2(@30 ppm), F2(@60 ppm), and F2(@90 ppm) were noted to be 30.2, 30.4, and 30.0%, respectively which are higher than F2 (27.9%). The value of replaced diesel with biogas was noted 0.09, 0.23, 0.24, and 0.22 kg/h for F2, F2(@30 ppm), F2(@60 ppm), and F2(@90 ppm), respectively under the full load condition. Lastly, CO and HC emissions were almost the same value with and without modified fuel for dual fuel mode at the full load. Nevertheless, NO emission was slightly increased with modified fuel compared to F2. From these findings, it can be suggested that 60 ppm multi-walled carbon nanotubes additive can be an optimum level for combustion, performance, and emissions under the dual fuel mode.Öğe Defatted spent coffee grounds-supported cobalt catalyst as a promising supercapacitor electrode for hydrogen production and energy storage(Springer, 2023) Karakas, Duygu Elma; Akdemir, Murat; Atelge, M. R.; Kaya, Mustafa; Atabani, A. E.The effect of several parameters, such as different Co2+ ratios, burning temperatures, and burning times, was examined by using defatted spent coffee grounds (DSCG) as organic waste to obtain the most effective catalyst for producing hydrogen. Under optimum conditions, the most active catalyst/metal ratio was obtained by burning 50% Co (2+) at 400 degrees C for 90 min. To measure the time-dependent amounts of hydrogen, 0.1 g of DSCG-Co catalyst was dissolved in 10 mL of a methanol solution containing 0.25 g sodium borohydride (NaBH4) at 30 degrees C. The maximum hydrogen generation rate obtained from the methanolysis of NaBH4 at 30 and 60 degrees C was found to be 8749 and 17,283 mL min(-1) gcat(-1), respectively, and the activation energy of the catalyst was found to be 23.2 kJ mol(-1). FTIR, ICP-OES, XRD, BET, and SEM-EDX analyses were performed for the characterization of the prepared DSCG-Co-Cat catalyst. Furthermore, a supercapacitor cell was constructed by using this catalyst as an active substance for electricity storage. The specific capacitance of the electrode at the current density of 1 A/g was calculated as 67 F/g for two-electrode systems. The results of electrochemical analysis of the prepared supercapacitor were found to be similar to the ideal supercapacitor curves. The obtained capacitance values are at very good levels in terms of the capacity and cost factors. The results indicated that the multifunctional capacitor-catalyst material produced by Co-doped waste coffee could constitute an important element in a hybrid system that includes capacitor and catalyst systems that can be installed in the future. [GRAPHICS] .
