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    Öğe
    A novel green approach for Cr(VI) removal: application of tomato stem-based hydrochar assisted Fenton-like process
    (Taylor & Francis Ltd, 2024) Alterkaoui, Aya; Belibagli, Pinar; Gun, Melis; Isik, Zelal; Eskikaya, Ozan; Yabalak, Erdal; Dizge, Nadir
    Environmentally friendly catalysts have come to the forefront due to the cost of chemically produced catalysts and the formation of by-products harmful to the environment. Millions of tons of plant waste are produced every year, some of which is disposed directly. In this study, tomato stem hydrochar (TSCH) was produced from waste tomato stems by the hydrothermal carbonisation (HTC) method, and its use as a catalyst was investigated. The optimisation of Cr(VI) removal from water was carried out using a Fenton-like process with a TSCH catalyst and resulted in 100% of Cr(VI) removal efficiency at 10 mg/L of Cr(VI) concentration, pH 2.00, 0.2 g/L of TSCH catalyst, 10 mu L/L of H2O2 and 60 minutes of reaction time. Fenton-like thermodynamic and kinetic data were analyzed, and the results were found to comply with the second-order in Cr(VI) removal. The reusability of the TSCH catalyst in Cr(VI) removal was investigated and it was emphasized that it was reusable for more than 5 uses. In conclusion, TSCH, which is an environmentally friendly, inexpensive and effective catalyst for Cr(VI) treatment in a Fenton-like process, can be used as an alternative catalyst for wastewater treatment in terms of both waste management and economic and environmentally friendly.
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    Öğe
    Hydrothermal Synthesis of Waste Black Tea Pulp and Tomato Stem Hydrochars and Comparison of Their Adsorption Performance of Safranin Dye
    (Springer Int Publ Ag, 2023) Alterkaoui, Aya; Belibagli, Pinar; Gun, Melis; Isik, Zelal; Dizge, Nadir; Yabalak, Erdal
    In this study, hydrochar prepared from black tea (BT) and tomato stem (TS) using subcritical water (SW) conditions was used as an adsorbent for color removal from Safranin-O (SO-Basic Red 2) dye wastewater. The use of black tea hydrochar (BTH) and tomato stem hydrochar (TSH) was investigated in the removal of Safranin-O dye from aqueous solutions by the adsorption process. In optimization studies, variables impacting the adsorption process such as adsorbent size, pH, dye concentration, adsorbent dosage, and shaking time were examined. As a result of optimization studies, removal efficiencies of 85.15% for BTH and 81.5% for TSH were achieved. In this study, the reuse cycle was also examined. Adsorption isotherm models, adsorption kinetic models, and thermodynamic studies have been studied to explain the relationships between the adsorption processes taking place. Data appropriate for the Freundlich and D-R isotherm models as well as the PSO kinetic model were obtained for TSH while defining the Freundlich isotherm model and the pseudo-second-order (PSO) kinetic model for BTH.
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    Öğe
    Photocatalytic activity of calcined chicken eggshells for Safranin and Reactive Red 180 decolorization
    (Pergamon-Elsevier Science Ltd, 2022) Eskikaya, Ozan; Gun, Melis; Bouchareb, Raouf; Bilici, Zeynep; Dizge, Nadir; Ramaraj, Rameshprabu; Balakrishnan, Deepanraj
    One of the most important problems affecting the environment today is the inability to adequately treat wastewater containing dyes. Among of the many treatment processes used in the treatment of dye-containing wastewater, photocatalytic based wastewater treatment processes attract the attention of scientists as a new, economically feasible, and promising approach which has been in practice for a few decades. However, in order to use these processes in wider areas, cheap and effective catalysts are still being developed today. In this study, the photocatalytic activity of eggshell-CaO produced from waste chicken eggshells was investigated for decolorization of Safranin (Basic Red 2) and Reactive Red 180 (RR180) dyes. First, sintering process was applied to the waste chicken eggshells at different temperatures (300, 600, 900 degrees C) in order to observe CaO formation from the eggshells. Second, the parameters such as photocatalyst amount, pH, concentration of dyes, and reaction time were optimized on dye removal efficiency in photocatalytic experiments. The optimum conditions were performed under visible light and found to be 1 g/L of catalyst amount (sintered at 900 degrees C), original solution pH (6.80 for Safranin and 6.60 for RR180), and 5 mg/L of dye concentration. The photocatalytic removal efficiencies of Safranin and RR180 dyes were 100% and 97.90%, respectively, under the determined optimum experimental conditions. The adsorption efficiency of the dyes that could be realized during the photocatalytic experiment was measured as 20.99% and 9.99% for Safranin and RR180 dyes, respectively.
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    Öğe
    Production of Waste Tomato Stem Hydrochar (TS-HC) in Subcritical Water Medium and Application in Real Textile Wastewater using Photocatalytic Treatment System
    (Springer Int Publ Ag, 2022) Alterkaoui, Aya; Eskikaya, Ozan; Gun, Melis; Yabalak, Erdal; Arslan, Hudaverdi; Dizge, Nadir
    Dye-containing wastewater emerges in many fields, especially in the textile industry. This type of wastewater has to be treated because of its negative effects on the environment. The treatment of wastewater containing dyes employs a variety of treatment techniques. However, it is important to use treatment systems that use nanoparticles of biomaterial origin. In this study, the use of photocatalytic treatment system with hydrochar obtained from tomato stems (TS-HC) in the purification of Methylene Blue (MB) and Remazol Brilliant Blue R (RBBR) dyes was investigated. For the optimization of the photocatalytic treatment system, light source, pH, TS-HC amount and initial dye concentration were tested. Furthermore, TS-HC reuse tests were carried out at the found optimal conditions and it was determined that both dyes had 10 reuse cycles. Optimum conditions for MB dye was obtained by adding 1 g/L catalyst into the solution with a pH value of 8 and an initial concentration of 15 mg/L, and 100% dye removal efficiency under UVA light. 97.4% dye removal efficiency was obtained by adding 2 g/L catalyst to the wastewater (pH 2) containing 15 mg/L RBBR dye under UVA light. Characterization analyzes with SEM, EDX and XRD of hydrochar obtained from waste tomato stem were performed. As a result of the photocatalytic experiments, TS-HC catalyst was used in the decolorization of real wastewater. It has been determined that the catalyst can decolorize the dye-containing real wastewater up to the lower limit of the appropriate value (260 Pt-Co) of the Turkish Water Pollution Control Regulation.