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Koleksiyon Analitik Kimya Anabi ...
169789

Comparative degradation of 5-fluorouracil in aqueous solution by using H2O2-modified subcritical water, photocatalytic oxidation and electro-Fenton processes

Gözmen, Belgin

This study investigated the degradation of the antineoplastic agent 5-fluorouracil (5-FU) widely applied to treat different cancers using different advanced oxidation processes such as electro-Fenton (EF), photocatalysis with TiO2, and H2O2-modified subcritical water oxidation. The treatment with the EF process was the most efficient compared to others. Interestingly, in the EF process, the oxidative degradation of 5-FU behaved differently depending on the anode used. At low currents (20 and 40 mA), Pt and DSA anodes performed better than BDD and Ti4O7 anodes. In contrast, at the higher current of 120 mA, the production of heterogeneous hydroxyl radicals (M(• OH)) became important and contributed significantly to the oxidation of 5-FU in addition to homogeneous • OH generated in th...

169790

Application of the central composite design to mineralization of olive mill wastewater by the electro/FeII/persulfate oxidation method

Gözmen, Belgin | Görmez, Özkan | Yabalak, Erdal

The olive mill wastewater is a major environmental problem, which is waiting for effective treatment. In this study, the mineralization of olive mill wastewater was investigated using the electro/FeII/persulfate process. The central composite design was utilized to examine the effect of each experimental variables (concentration of persulphate and FeII, treatment time and constant current) on the mineralization of olive mill wastewater. The optimum chemical oxygen demand removal percentage was obtained as 71.2% where the reaction conditions were 200 mA current, 250 mM persulphate, 25 mM FeII, and 6 h reaction time. In addition, the maximum percentage of total phenolic removal and the energy consumption were 88% and 4.50 kWh/kgCOD, respectively, which were obtained at the same reaction ...

169806

Synthesis of biomass-based BiOI@Hydrochar heterogeneous catalyst and investigation of its activity in sonocatalytic process

Gözmen, Belgin | Çomak, Gürbüz | Görmez, Özkan

Innovative studies in recent years to remove pollutants discharged into water resources through various means are critically important for protecting existing water resources. An important part of these studies is heterogeneous catalysis-based AOPs, where new generation composite materials are used and high organic pollutant degradation has been achieved. This study used the solvothermal approach to produce a BiOI@BH sonocatalyst doped with hydrochar (BH). A variety of analysis techniques, including XRD, FESEM, EDS, FTIR, DRS, and BET surface analysis, were used to assess changes in the physico-chemical properties of the BiOI@BH structure in comparison to BiOI. Both the adsorption and sonocatalytic degradation processes for the methylene blue aqueous solution were found to be more successf...

169696

Efficient removal of insecticide “imidacloprid” from water by electrochemical advanced oxidation processes

Turabik, Meral | Gözmen, Belgin

The oxidative degradation of imidacloprid (ICP) has been carried out by electrochemical advanced oxidation processes (EAOPs), anodic oxidation, and electro-Fenton, in which hydroxyl radicals are generated electrocatalytically. Carbon-felt cathode and platinum or boron-doped diamond (BDD) anodes were used in electrolysis cell. To determine optimum operating conditions, the effects of applied current and catalyst concentration were investigated. The decay of ICP during the oxidative degradation was well fitted to pseudo-first-order reaction kinetics and absolute rate constant of the oxidation of ICP by hydroxyl radicals was found to be kabs(ICP)=1.23×109 L mol−1 s −1 . The results showed that both anodic oxidation and electro-Fenton process with BDD anode exhibited high minera...

169792

Adsorption of Malachite Green on Fe-modified biochar: influencing factors and process optimization

Gözmen, Belgin

Paper sludge and wheat husk biochar was converted to a Fe-composite through a simple coprecipitation process and its adsorption behavior was tested against an emerging pollutant, Malachite Green (MG). Response surface methodology was employed to determine the optimum experimental conditions and the interactions between pH, initial MG concentration, temperature and treatment time. The maximum adsorption percentage obtained experimentally was 97.1%, whereas the Box– Behnken design predicted a maximum adsorption of 98%, at pH 6.16, initial MG concentration of 6.56 ppm, temperature of 34.75°C and treatment time of 22 min. Compared with the original biochar, the Fe-modified sample improved the adsorption of MG by ~34%. The adsorption mechanism followed the Langmuir model (qmax = 172.3 mg/...

169692

Indirect Electrochemical Treatment of Bisphenol A in Water via Electrochemically Generated Fenton's Reagent

Gözmen, Belgin

Bisphenol A (BPA) has been treated with electrochemically generated Fenton's reagent in aqueous medium. Hydroxyl radicals that were formed in Fenton's reagent reacted with the organic substrate producing two different isomers of monohydroxylated product and, upon successive hydroxylation, mainly one dihydroxylated product. Further hydroxylation first degraded one of the aromatic rings, and the side chain thus formed was then cleaved off the other aromatic ring. The second aromatic ring was also degraded upon successive hydroxylations. Small saturated and unsaturated aliphatic acids were the last products prior to mineralization. It was found that use of cuprous/cupric ion pair resulted a faster conversion of BPA and faster mineralization when compared using ferrous/ferric ions, b...

169700

Valorization of loquat seeds by hydrothermal carbonization for the production of hydrochars and aqueous phases as added-value products

Gözmen, Belgin | Görmez, Özkan | Saçlı, Barış | Çalhan Doğan, Selda

In the framework of circular bio-economy, waste loquat seeds were utilized for the production of two addedvalue products. The seeds were hydrothermally carbonized at a temperature range of 150–250 ◦C and time range 2–6 h and the resultant hydrochars and aqueous phases were characterized using various methods. The optimum higher heating value of 30.64 MJ kg− 1 , ash content of 1.99 wt % and alkali index of 0.05 were achieved for the hydrochar prepared at 250 ◦C and 6 h, establishing its suitability for energy-related applications. The aqueous phase obtained at 250 ◦C and 6 h achieved 90% scavenging of the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and had a IC50 value of 43.71 μg mL− 1 . Principal component analysis showed that the production of phenols, ketones, alkenes a...

169814

Electrolysis of coal slurries to produce hydrogen gas: Relationship between CO2 and H2 formation

Gözmen, Belgin

The purpose of this study was to produce hydrogen gas by electrolysis of coal slurries and to investigate the relation between hydrogen (H2) and carbon dioxide (CO2) formation. Electrolysis of coal slurries was evaluated at 40 °C and 1.0 V cell potential to examine H2 and CO2relationship. When electrolysis was performed after the coal slurry was mixed with Fe(II)/Fe(III) ions and stirred overnight (>12 h), no CO2 gas was observed at the anode compartment. The results of total organic carbon (TOC) indicated that after electrolysis, few organic compounds were transformed into the solution and these organic compounds did not convert into CO2. GC analysis, on the other hand, revealed that the H2 collected at the cathode was pure and did not require any further purification process. Hydrogen ge...

169799

A dual purpose aluminum-based metal organic framework for the removal of chloramphenicol from wastewater

Gözmen, Belgin | Geçgel, Cihan | Görmez, Özkan | Turabik, Meral

The presence of antibiotics in the aquatic environment can cause significant environmental and human health problems even at trace concentrations. Conventional treatment systems alone are ineffective in removing these resistant antibiotics. To address this problem, oxidation and adsorption techniques were used to explore the removal of recalcitrant antibiotic chloramphenicol (CAP). An aluminum-based metal-organic framework (AlMIL) with high surface area and extended porosity, was prepared and used both as adsorbent and catalyst for the oxidation of CAP. Characterization of the Al-MIL revealed a large surface area of 1137 m2 g− 1 , a homogeneous microporous structure, good crystallinity, and particle size in the range of 200–400 nm. Adsorption of CAP on AlMIL achieved equilibrium afte...

169817

Direct Liquefaction of High-Sulfur Coals:  Effects of the Catalyst, the Solvent, and the Mineral Matter

Gözmen, Belgin

Two low-rank coals with high sulfur contents (Gediz subbituminous coal:  7.6 wt % S:dry basis. Çayirhan lignite:  5.7 wt% S:dry basis.) were subjected to hydroliquefaction. Liquefaction conditions included dry or solvent mediated runs under pressurized hydrogen without added catalyst or with the impregnated catalyst precursor ammonium heptamolybdate (AHM). Gediz coal having higher sulfur content gave 90% conversion in the absence of catalyst and solvent. Maximum conversion (98%) and maximum oil + gas yield (70%) from this coal were obtained by impregnating AHM onto coal and carrying out liquefaction in H2/tetralin system at 450 °C for 30 min. Under the same conditions, Çayirhan lignite gave 85% conversion and 70.5% oil + gas yield. The superior hydrodesulfurization effect of impregnated AH...

169834

Degradation of isoniazid by anodic oxidation and subcritical water oxidation methods: Application of Box–Behnken design

Gözmen, Belgin | Görmez, Özkan | Doğan Çalhan, Selda

Pharmaceutical compounds released into the aquatic environment are known to cause toxic effects on the environment. Isoniazid is widely used in the treatment of tuberculosis and is, therefore, frequently encountered in environmental waters. In this study, the degradation of isoniazid was investigated by anodic oxidation and subcritical water oxidation method which are members of Advanced Oxidation Processes. The Box–Behnken Design was used to determine the effects of current, initial concentration, and electrolysis time on mineralization in the anodic oxidation process, which carried out a cell with a Pt cathode and boron-doped diamond anode. The highest mineralization value of 78.14% was achieved at optimal conditions of 300 mA, 3 h, and 100 mg/L initial concentration. The degradation of ...

169811

Fe-modified sporopollenin as a composite biosorbent for the removal of Pb2+ from aqueous solutions

Gözmen, Belgin

The role of Fe-modified sporopollenin (Fe-Sp) biomass in Pb2+ removal from aqueous solutions was investigated by batch biosorption technique. The prepared biosorbent was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometry, and Fourier transform infrared spectroscopy. The influence of pH, contact time, biosorbent dose, and initial concentration on biosorption process were optimized by using a four factor Box–Behnken design combined with response surface methodology. The results indicated a positive adsorption behavior of Fe-Sp and a strong pH dependency of the process. The optimum predicted parameters were determined as follows: biosorbent dosage 0.5 g, pH of 6.75, contact time 104 min, and initial Pb2+ concentration of 25.42 ppm. The Freundlich isotherm mode...

169838

Removal of imipramine using advanced oxidation processes: Degradation products and toxicity evolution

Doğan Çalhan, Selda | Görmez, Özkan | Gözmen, Belgin | Şüküroğlu, Ayça

Pharmaceuticals are frequently detected in natural and wastewater bodies, and are very important in environmental toxicology because of their stable nature. Advanced oxidation methods used to remove contaminants are of great benefit, especially removing pharmaceuticals unsuitable for biodegradation. In this study, imipramine was degraded by anodic oxidation and subcritical water oxidation, which are advanced oxidation methods. The determination of degradation products was performed by Q-TOF LC/MS analysis. The genotoxicity and cytotoxicity of the degradation samples were determined by the in vivo Allium Cepa method. Among the anodic oxidation samples, the lowest cytotoxicity was obtained after using 400 mA current, and 420 min of degradation time. No cytotoxic effect was observed in any su...

169830

Modulator-assisted solvothermal synthesis of CeO2 derived from Ce-BDC MOFs: effect on oxygen evolution reaction performance

Gözmen, Belgin | Görmez, Özkan | Çirmi, Doğan

In this study, the morphological, structural, and electrocatalytic properties of Ce-BDC-based metal–organic framework (MOF) materials synthesized under various conditions were comprehensively investigated. Four types of structures Ce-BDC, Ce-BDC-P, Ce-BDC*, and Ce-BDC*-P were prepared using a solvothermal method. The synthesis was carried out both under ambient and pressurized (P) conditions, and with or without acetic acid used as a modulator (*). To optimize the synthesis parameters, the amount of acetic acid (12.5, 25, and 50 Meq) was systematically varied, and among the samples, Ce-BDC*-50-P (synthesized under pressurized conditions with 50 Meq of acetic acid) was identified as exhibiting the highest electrocatalytic performance. Structural characterization was carried out using XRD, F...

170172

Application and Performance Evaluation of Chemical Coagulation, Electrocoagulation, Electro-Fenton and Anodic Oxidation Processes in the Treatment of Glass Fiber Manufacturing Wastewater

Gözmen, Belgin | Görmez, Özkan

This study investigated the oxidation of wastewater generated during the production of glass fiber manufacturing material, which contains high organic carbon (18.32 g/L) and has a pH of 8.8, by chemical coagulation, electrocoagulation and electro-advanced oxidation techniques. It was determined that the total organic content (TOC) of wastewater was reduced by 53% using the chemical coagulation method. After electrocoagulation with Al/Al electrode pair for 300 minutes at 500 mA, 73% TOC removal was achieved at pH 8.8. While 50% TOC removal was completed in 2 h at 400 mA in electrocoagulation with Fe/Fe electrode pair, 71% TOC removal was obtained in the combined electrocoagulation/electro-Fenton process by adding hydrogen peroxide to the medium under the same conditions. In addition, it was...

169801

Comparison of MIL-101(Fe) and amine-functionalized MIL-101(Fe) as photocatalysts for the removal of imidacloprid in aqueous solution

Gözmen, Belgin | Geçgel, Cihan | Turabik, Meral

One of the attractive iron-based metal organic framework (MOF) MIL-101(Fe) (Material Institute Lavoisier, MIL) and amine-functionalized NH2-MIL-101(Fe) materials were synthesized by conventional solvothermal method and characterized by TGA (Thermo Gravimetric Analysis), SEM (Scanning Electron Microscopy), XRD (X-Ray Diffractograms), BET (Braunner Emmet Teller) and FTIR (Fourier Transform Infrared Spectroscopy). Characterization results indicated that MIL101(Fe) materials have well defined morphology, good thermal stability, high surface area and also high porosity. These MOF materials were used as photocatalysts for photodegradation of a pesticide, imidacloprid (IMC). The response surface methodology (RSM) was applied in designing the IMC photodegradation experiments for evaluating the...

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