Browsing by Author "Gokkus, K."

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Characterization of Divalent Metal Soaps of Cannabis Sativa Seed Oil
(2023.01.01) Yetgin, S.; Egbuchunam, T.; Okieimen, F.; Gokkus, K.; Guney, K.
In this study, the structural characteristics and thermal degradation behaviour of barium, calcium and zinc soaps of hemp seed oil prepared using the metathesis method are reported. Scanning electron micrographs of the metal soaps showed similar plate-like microstructures and are indicative of an orderly packed particulate structure. The bands at 1509, 1539 and 1543 cm(-1) in the FTIR spectra showed the association of the carboxylate ion with Ba, Ca and Zn ions respectively The thermal decomposition consisted of one single step on the weight loss - temperature curves located around 250 - 450 C-degrees for all the divalent metal soaps at the various heating rates and the observed loss in weight which occurred before 200 C-degrees was minimal (< 10%). The average values of the apparent activation energy for the thermal process were 18.73, 13.77 and 8.48 kJ/mol for Zn-HSO, Ca-HSO and Ba-HSO respectively.
Polymeric Adsorbent for the Effective Removal of Toxic Dyes from Aqueous Solutions: Equilibrium, Kinetic, and Thermodynamic Modeling
(John Wiley and Sons Inc, 2024) Oter, C.; Gokkus, K.; Gur, M.; Butun, V.
This study investigates the adsorption behavior of anionic (Congo red, Eosin yellow) and cationic (Malachite green) dyes on synthesized TD polymer particles, highlighting the material's potential as an effective adsorbent for industrial wastewater treatment. Key operational parameters, including initial solution's pH, contact time, initial dye concentration, and temperature, were systematically evaluated to determine their influence on adsorption efficiency. The experimental data demonstrated that the Langmuir isotherm provided the best fit for all three dyes, indicating monolayer adsorption with maximum adsorption capacities of 153.8 mg/g for Malachite green, 49.36 mg/g for Congo red, and 227.9 mg/g for Eosin yellow. Kinetic analysis revealed that the adsorption of Malachite green and Congo red followed pseudo-second-order kinetics, while Eosin yellow adsorption was better described by the intra-particle diffusion model. Thermodynamic assessments, including Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°), confirmed the spontaneous and endothermic nature of the adsorption processes for Malachite green and Eosin yellow, contrasting with the exothermic behavior observed for Congo red. These findings underscore the versatility and effectiveness of TD polymer particles in removing both anionic and cationic dyes from aqueous solutions. Further research could explore material optimization and real-world applications to broaden their utility in sustainable water treatment strategies.
Preparation of versatile polymer particles and their application for elimination of bromophenol blue and phenol from aqueous environment
(Elsevier B.V., 2024) Gokkus, K.; Oter, C.; Amlani, M.; Gur, M.; Butun, V.
Cellulose, activated carbon, zeolite, and similar materials have a weak effect against anionic pollutants. Therefore, further modifications are needed for the use of such substances. In this study, polymer particles (GD) that were economical and directly effective against anionic pollutants were synthesized as an alternative. GD particles were synthesized with glutaraldehyde and diethylenetriamine as monomers for the first time. The polymer particles were characterized in detail. Then, GD particles were used in the adsorption of anionic Bromophenol blue (BPB) and phenol (PH). As a result, it was determined that i) the adsorption process between GD particles, Bromophenol blue and phenol was chemisorption, ii) the adsorption of BPB and PH on to GD particles obeyed the Langmuir isotherm and pseudo second order kinetic model. pH, temperature, initial dye concentration, adsorbent dosage, and contact time were determined orderly 4, 50 °C, 300 mg L−1, 10 mg, and 180 mins for BPB and 5, 50 °C, 10 mg L−1, 15 mg, and 30 mins for PH. The maximum adsorption capacities of GD polymer particles for BPB and PH were ascertained as 136.40 mg g−1 and 98.26 mg g−1, respectively. As a result, it was produced economical, simple, feasible, and functional adsorbents against anionic pollutants.
Synthesis and characterization of azo cross-linked polymer as a new catalyst for the production of hydrogen gas by methanolysis of NaBH4
(2024.01.01) Gokkus, K.; Gür, M.; Bütün, V.
The intensive use of fossil fuels has profound impacts on all ecosystems, primarily contributing to global warming through greenhouse gas emissions. To mitigate these impacts, alternative energy sources like hydrogen are crucial. In this study, azo cross-linked polymer with 4-aminophenyl sulfone and resorcinol were synthesized by a green synthesis method. The polymer was extensively characterized by Fourier-transform infrared spectroscopy, Brunner-Emmett-Teller analysis, thermogravimetric analysis, and scanning electron microscopy-energy dispersive x-ray spectroscopy analyses. Subsequently, the catalytic performance of the polymer in hydrogen production from NaBH4 via methanolysis was investigated. At this stage, the parameters affecting hydrogen production (catalyst and NaBH4 amounts, MeOH volume and temperature) were systematically studied to determine optimum conditions. The maximum HGR values of the polymer was 13,100 and 27,000 mL min(-1) g(cat)(-1) at 30 and 60 degrees C, respectively and its activation energy was 10.45 kJ mol(-1). After optimization, the reusability of azo polymer was tested with 5 cycles. The theoretical volume of hydrogen was produced in all 5 cycles. But with each cycle, the hydrogen production time increased. The main purpose of this study was to demonstrate novel azo-linked polymers with high catalytic activity in hydrogen production. The results revealed significant potential of the polymer for hydrogen generation. Overall, this research highlights the promising role of azo cross-linked polymers as effective catalysts for hydrogen production, offering new perspectives and pathways towards sustainable energy solutions.
Synthesis and Characterization of Polymer Particles as Metal-Free Catalysts for Electrooxidation and Methanolysis of Sodium Borohydride
(2024.01.01) Gokkus, K.; Kaya, S.; Yildiz, D.; Saka, C.; Gür, M.; Bütün, V.; Kivrak, H.
In this study, trimethylolpropane triglycidyl ether/diethylenetriamine (TD) and glutaraldehyde/diethylenetriamine (GD) polymer particles are synthesized as catalysts for hydrogen production from NaBH4 methanolysis and NaBH4 electrooxidation. SEM, FT-IR and TGA characterization methods are applied to determine the surface morphologies, chemical structures, thermal stability and decomposition of the synthesized polymer particles. The parameters affecting the hydrogen generation rate on NaBH4 methanolysis are investigated and optimum conditions are determined. Under optimum conditions, the hydrogen generation rates of TD and GD polymer particles are obtained as 34903.2 and 97998 mL/min.gcat, respectively. The activation energies of TD and GD polymer particles are also calculated as 16.86 and 18.14 kJ/mol, respectively. The catalytic activities of polymer particles as anode catalysts in NaBH4 electrooxidation are determined by CV, CA, EIS analyses. The specific activities of TD and GD polymer particles are acquired as 0.54 and 0.64 mA/cm2, respectively. These results indicate that the synthesized polymer particles are promising catalysts for electrooxidation and methanolysis of sodium borohydride. In this study, trimethylolpropane triglycidyl ether/diethylenetriamine (TD) and glutaraldehyde/diethylenetriamine (GD) polymer particles are synthesized as catalysts for hydrogen production from NaBH4 methanolysis and NaBH4 electrooxidation. The obtained results indicate that the synthesized polymer particles are promising catalysts for electrooxidation and methanolysis of sodium borohydride. image
Synthesis and Characterization of Polymer Particles as Metal-Free Catalysts for Electrooxidation and Methanolysis of Sodium Borohydride
(John Wiley and Sons Inc, 2024) Gokkus, K.; Kaya, S.; Yildiz, D.; Saka, C.; Gür, M.; Bütün, V.; Kivrak, H.
In this study, trimethylolpropane triglycidyl ether/diethylenetriamine (TD) and glutaraldehyde/diethylenetriamine (GD) polymer particles are synthesized as catalysts for hydrogen production from NaBH4 methanolysis and NaBH4 electrooxidation. SEM, FT-IR and TGA characterization methods are applied to determine the surface morphologies, chemical structures, thermal stability and decomposition of the synthesized polymer particles. The parameters affecting the hydrogen generation rate on NaBH4 methanolysis are investigated and optimum conditions are determined. Under optimum conditions, the hydrogen generation rates of TD and GD polymer particles are obtained as 34903.2 and 97998 mL/min.gcat, respectively. The activation energies of TD and GD polymer particles are also calculated as 16.86 and 18.14 kJ/mol, respectively. The catalytic activities of polymer particles as anode catalysts in NaBH4 electrooxidation are determined by CV, CA, EIS analyses. The specific activities of TD and GD polymer particles are acquired as 0.54 and 0.64 mA/cm2, respectively. These results indicate that the synthesized polymer particles are promising catalysts for electrooxidation and methanolysis of sodium borohydride.
Synthesis of azo polymers and their catalytic performance in hydrogen production via NaBH4 methanolysis
(2024.01.01) Gokkus, K.; Ozbal, A.; Senturan, U.M.; Gür, M.; Bütün, V.
The extensive use of fossil fuels has a profound impact on ecosystems and contributes to global warming through the emission of greenhouse gases. To mitigate these effects, alternative energy sources such as hydrogen are crucial. In this study, a green synthesis approach was used to prepare an azo cross-linked polymer containing 4aminophenyl ether and resorcinol. The synthesized polymer was thoroughly characterized by FT-IR, BET, TGA, Zeta Potential and SEM-EDS analyses. The catalytic performance of the polymer in hydrogen production from NaBH4 4 via methanolysis was then investigated. Various parameters affecting hydrogen production, including catalyst and NaBH4 4 amounts, methanol volume and temperature, were systematically investigated to identify the optimum conditions. The polymer exhibited maximum hydrogen generation rate (HGR) of 12,619 mL H2 2 min-1 1 g cat- 1 at 60 degrees C, respectively, with an activation energy of 24.22 kJ mol-1.- 1 . After optimization, the reusability of the polymer was evaluated over five cycles and the theoretical hydrogen generation rates were consistently achieved; however, the hydrogen generation time increased with each subsequent cycle. The primary objective of this research was to highlight novel azo linked polymers with potent catalytic activity in hydrogen generation, demonstrating the significant potential of the polymer to advance hydrogen generation. Ultimately, this study highlights the promising role of azo cross-linked polymers as effective catalysts for hydrogen production, offering new avenues and perspectives towards sustainable energy solutions.
Synthesis of azo polymers and their catalytic performance in hydrogen production via NaBH4 methanolysis
(Elsevier Ltd, 2024) Gokkus, K.; Ozbal, A.; Senturan, U.M.; Gür, M.; Bütün, V.
The extensive use of fossil fuels has a profound impact on ecosystems and contributes to global warming through the emission of greenhouse gases. To mitigate these effects, alternative energy sources such as hydrogen are crucial. In this study, a green synthesis approach was used to prepare an azo cross-linked polymer containing 4-aminophenyl ether and resorcinol. The synthesized polymer was thoroughly characterized by FT-IR, BET, TGA, Zeta Potential and SEM-EDS analyses. The catalytic performance of the polymer in hydrogen production from NaBH4 via methanolysis was then investigated. Various parameters affecting hydrogen production, including catalyst and NaBH4 amounts, methanol volume and temperature, were systematically investigated to identify the optimum conditions. The polymer exhibited maximum hydrogen generation rate (HGR) of 12,619 mL H2 min⁻¹ gcat⁻¹ at 60 °C, respectively, with an activation energy of 24.22 kJ mol⁻¹. After optimization, the reusability of the polymer was evaluated over five cycles and the theoretical hydrogen generation rates were consistently achieved; however, the hydrogen generation time increased with each subsequent cycle. The primary objective of this research was to highlight novel azo linked polymers with potent catalytic activity in hydrogen generation, demonstrating the significant potential of the polymer to advance hydrogen generation. Ultimately, this study highlights the promising role of azo cross-linked polymers as effective catalysts for hydrogen production, offering new avenues and perspectives towards sustainable energy solutions.