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    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
    Effects of hydrogen peroxide, temperature and treatment time on degradation properties of polyethersulfone ultrafiltration membrane
    (TUBITAK, 2022) Özay, Yasin; Yabalak, Erdal; Dizge, Nadir
    Oxidative cleaning agents such as hydrogen peroxide (H2O2) and sodium hypochlorite (NaClO) used in water and wastewater treatment play an important role in the degradation and rapid aging of the polymeric membranes. In addition, when the temperature is above the maximum operating range of the membrane, it negatively affects the membrane performance. H2O2, which is also known as a green and environmentally friendly strong oxidant because of releasing only water as a by-product, can provide good cleaning efficiency under temperature, but its influence on membrane aging is not fully understood. In this study, the aging of polyethersulfone (PES) ultrafiltration (UF) membrane using H2O2 under high-temperature conditions and degradation of the polymeric membrane were systematically investigated using response surface methodology (RSM). The effects of H2O2 concentration, temperature, and treatment time were tested on membrane flux, contact angle, pore size, and porosity for decomposed membrane. The results showed that normalized permeability was significantly changed approximately 2.34-folds by H2O2 concentration at an exposure dose of 5 mM and 373 K temperature. Moreover, the largest pore sizes as 161.23 nm and 160.73 nm were obtained at the conditions of 2.5 mM H2O2 concentration and 373 K temperature. The lowest contact angle (54.76°) and porosity (61.88%) were obtained at the same conditions. The results depicted that H2O2 can be used for membrane cleaning with minimum membrane degradation at moderate conditions. © TÜBİTAK
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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
    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.