Browsing by Author "Yildiz, Burcin"

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Adsorption of Chlortetracycline From Aqueous Solution by Chitin
(Taylor & Francis inc, 2020) Tunc, Muskun Sara; Hanay, Ozge; Yildiz, Burcin
In this study, the performance of chitin for removing chlortetracycline (CTC) from aqueous solutions was assessed. The effects of pH, chitin dose, CTC concentration and contact time on CTC adsorption by chitin were investigated. The maximum CTC removal efficiency of 82.9% was determined at pH 7, chitin dose of 5 g/L, CTC concentration of 8.8 mg/L and contact time of 120 min. The highest CTC adsorption capacity was found as 12.01 mg/g for CTC of 82.2 mg/L concentration at pH 7. The results demonstrated that CTC removal efficiency decreased from 82.9% to 73.0% with increasing CTC concentration from 8.8 to 82.2 mg/L. The equilibrium data for CTC adsorption indicated a good fit to the Freundlich isotherm model. Pseudo-second-order kinetic model was the best model for describing the adsorption reactions.
Efficient Removal of Paracetamol by Manganese Oxide Octahedral Molecular Sieves (oms-2) and Persulfate
(Springer international Publishing Ag, 2020) Tepe, Ozlem; Tunc, Zeynep; Yildiz, Burcin; Sahin, Mehmet
Pharmaceutically active compounds are gradually increasing in different environments such as surface waters, groundwater, and soil. Paracetamol is a pharmaceutical used as a pain reliever and antipyretic. In this study, paracetamol removal was investigated using manganese oxide octahedral molecular sieves (OMS-2) and persulfate. In the first stage of the study, OMS-2 was produced in a laboratory, and then paracetamol removal was investigated in OMS-2 only, persulfate only, and a combination of OMS-2/PS. When using 5 mM persulfate and 0.1 g/L OMS-2, the paracetamol removal efficiency increased to 99.5%. The use of OMS-2 with persulfate resulted in faster and more effective removal of paracetamol compared with OMS-2 only and persulfate only. In another stage of the study, the effects of reaction temperature and pH were investigated. For this purpose, the pH was changed in the range of 2-8, while the temperature was examined at 20, 30, and 40 degrees C. A high rate of paracetamol removal occurred at all pH and temperature values tested. Paracetamol removal was investigated at different OMS-2 and persulfate concentrations, optimum OMS-2 amount was determined as 0.1 g/L, and optimum persulfate dosage was 20 mM. The reusability of the OMS-2 catalyst was investigated, showing a decrease in removal efficiency with each cycle. In the later stages of the study, free radical quenching studies, the effect of humic acid and inorganic anions and the characterization of the synthesized OMS-2 were performed.
In-Situ Generation of H2o2 in Heterogeneous Fenton-Like Process With Fe/Ni Bimetallic Particle for Metronidazole Degradation
(Taylor & Francis inc, 2022) Yildiz, Burcin; Yucel, Ahmet; Hanay, Ozge
A microscale Fe/Ni bimetallic particle was examined to convert O-2 to H2O2 and further to center dot OH radicals and to degrade metronidazole (MNZ) antibiotic in a heterogeneous Fenton-like reaction. The properties of the bimetallic particle before and after the reaction were studied using SEM, EDX, XRD, and BET techniques. The complete removal of MNZ was achieved within 15 min with an initial pH of 3, oxygen flow rate of 150 L/h, Fe/Ni of 1 g/L, and MNZ of 25 mg/L. Under these conditions, the maximum H2O2 concentration of about 31 mg/L was generated but only 27% of TOC was removed after 60 min. The presence of NaCl and the high ionic strength accelerated the iron dissolution and MNZ removal efficiency. The reaction was mainly inhibited at the solution pH of 7, implying the significance of solution pH in Fenton-like process. Besides, the possible MNZ degradation pathway was further proposed based on the intermediates identified by GC/MS. Acetamide was monitored as the degradation intermediate. The results showed a significant contribution on the usage of a catalyst for in-situ generation of H2O2 via the activation of dissolved oxygen.
Multi-response/Multi-step Optimization of Heterogeneous Fenton Process With Fe3o4 Catalyst for the Treatment of Landfill Leachate
(Springer int Publ Ag, 2021) Tasci, Salih; Ozguven, Ayse; Yildiz, Burcin
Since conventional biological treatment methods are not sufficient alone to treat landfill leachate, this study investigated the efficacy of the heterogeneous Fenton process as a preliminary treatment technique. With this aim, a two-level factorial design combined with the response surface methodology (RSM) was used to optimize the operating parameters for the heterogeneous Fenton process used for treatment of leachate. The surface morphology and elemental analysis of Fe3O4 nanoparticles used in the heterogeneous Fenton process were completed with scanning electron microscope (SEM), energy dispersive X-ray (EDX) and Fourier transform infrared spectroscopy (FT-IR). In order to obtain maximum 75% chemical oxygen demand (COD) removal for treatment of leachate with the heterogeneous Fenton process, the optimum conditions for H2O2 and Fe3O4 dosages, stirring rate and initial pH parameters were 800 mg/L, 334.54 mg/L, 255 rpm and 3.34, respectively. The results obtained show the heterogeneous Fenton process abides by the second-order model (R-2 = 0.9896), and the variables mentioned above were confirmed to significantly affect the COD removal efficiency. Response surface graphs show the use of higher pH and chemical agents do not increase the COD removal efficiency. This study proves the applicability of the multi-response optimization program for treatment of leachate from a landfill site representing a serious problem in environmental terms.
Removal of Paracetamol From Aqueous Solution by Wood Sawdust-Derived Activated Carbon: Process Optimization Using Response Surface Methodology
(Taylor & Francis inc, 2022) Tunc, Muslun Sara; Yildiz, Burcin; Tasar, Seyda
The removal of paracetamol pharmaceutical from the aqueous solution by activated carbon prepared from wood sawdust (WSAC) was studied in the current research. The Response Surface Methodology (RSM) was used to model WSAC paracetamol removal, optimize operational parameters, and determine the impact of operational parameters such as adsorbent dosage, initial concentration of paracetamol, and contact time. According to the results of variance analysis (ANOVA), the quadratic model was statistically significant (P < 0.0001), and the determination coefficient value (R-2=0.9847) was high. The high determination coefficient value of the quadratic model indicated that the experimental results adapted well with the predicted results, that is, the model was valid for envisaging the experimental results. The optimum conditions were obtained to be 0.16 g/100 mL WSAC dosage, 11.52 mg/L initial paracetamol concentration, and 90.52 min contact time by the desirability function, resulting in the paracetamol removal of 99.24%. The results of the isotherm studies indicated that the isotherm equations of Langmuir, Temkin, and Dubinin all fit the paracetamol adsorption data. The maximum adsorption capacity (q(max)) of WSAC was calculated as 15.90 mg/g using the Langmuir isotherm equation. Kinetic study results revealed that the pseudo-second-order kinetic model adapted well to the paracetamol adsorption data.