Gülin Ersöz

Treatment of aniline by catalytic wet air oxidation: Comparative study over CuO/CeO2 and NiO/Al2O3

The treatment of aniline by catalytic wet air oxidation (CWAO) was studied in a bubble reactor. The experiments were performed to investigate the effects of catalyst loading, temperature, reaction time, air flow rate, and pressure on aniline removal. The catalytic effects of the prepared nanostructured catalysts, CuO/CeO(2) (10% wt) and NiO/Al(2)O(3) (10% wt), on the CWAO treatment efficiency were also examined and compared. The prepared catalysts seem to be active having an aniline removal of 45.7% with CuO/CeO(2) and 41.9% with NiO/Al(2)O(3). The amount of N(2) formed was approximately the same for both of the catalysts.

Novel Catalysts in Advanced Oxidation of Organic Pollutants

This brief summarizes the role of certain catalysts and associated processes that are involved in the reduction or elimination of hazardous substances from wastewater and the exploitation of renewable raw materials. The authors begin by providing a summary of the most recent developments in catalysts used in the advanced oxidation of organic pollutants in aqueous phase. Advanced Oxidation Processes (AOPS) are described in terms of homogeneous and heterogeneous catalysts. Some emphasis is placed on the role nanocatalysts, perovskite-type catalysts, and green catalysts play in several AOPs such as Fenton Chemistry, photocatalytic oxidation, and the hybrid technologies that combine different processes. Catalyst preparation, characterization, reaction chemistry, and process technology are described. Specific wastewater case studies which illustrate the role of these catalysts in AOPs completes the brief

Comparative Study Using Chemical Wet Oxidation for Removal of Reactive Black 5 in the Presence of Activated Carbon

AbstractThe objective of this study was to assess the feasibility of various chemical wet oxidation techniques to remove azo dyes from wastewater. The performances of three different catalytic wet oxidation techniques were evaluated: catalytic wet air oxidation (CWAO), catalytic wet peroxide oxidation (CWPO), and hydrogen peroxide promoted wet air oxidation (PCWAO), using activated carbon as a catalyst to evaluate the degradation and decolorization of Reactive Black 5 in aqueous solution. The experiments were also conducted to investigate the optimum operating conditions of the processes, such as temperature, pH, activated carbon loading, H2O2 loading, and reaction time. This investigation revealed that all of the wet oxidation techniques showed similar results and rather high removal efficiencies, but at different operating conditions. At the optimized conditions, the degradation was generally approximately 85% and decolorization was nearly 95% in each case. The operating conditions were as follows: in t...

Photocatalytic and photo-Fenton-like degradation of methylparaben on monolith-supported perovskite-type catalysts

ABSTRACT Methylparaben was degraded in the presence of ABO3 perovskite catalysts (A: La, Bi, and B: Ti-Fe, Fe) synthesized on a monolithic structure using the sol–gel method. The catalysts were characterized by BET, SEM, XRD, and FTIR. The highest degradation was observed using BiFeO3 on the monolithic structure. The methylparaben degradation and iron leaching were 82.8% and 0.06 ppm, respectively, under the optimum conditions, which were pH=7, [H2O2]0=0.5 mM, and 0.1 g/L BiFeO3 loading. The toxicity tests were carried out by cress seeds and 1.09% inhibition was observed. Methylparaben degradation followed the second-order reaction kinetics, whereas the activation energy was 54 kJ/mol.

Advanced Oxidation Processes

Various organic pollutants are discharged into the aquatic environment. Most of them are not only toxic but also nonbiodegradable. Hence they cannot be treated by biological wastewater treatment plants or other conventional methods. And consequently a need arises to develop effective methods for the degradation of organic pollutants, either to less harmful compounds or to their complete mineralization. Advanced Oxidation Processes (AOPs) have attracted increasing attention due to their potential capability in the removal of recalcitrant organic pollutants. This chapter presents the general process principles on Advanced Oxidation Processes namely and discusses catalysis in Advanced Oxidation Processes. The usage and mechanism of both homogeneous and heterogeneous catalysts in Fenton Oxidation, Catalytic Wet Air Oxidation and Ozonation are discussed comprehensively.

Visible light assisted Fenton oxidation of tartrazine using metal doped bismuth oxyhalides as novel photocatalysts

This research focused on the abatement of the model food dye, tartrazine, using visible light photo-Fenton oxidation with novel bismuth oxyhalide catalysts. Bismuth-oxyhalide and metal doped bismuth oxyhalide catalysts (BiOCl, Cu-BiOCl, and Fe-BiOCl) were synthesized via the facile co-precipitation method. The catalysts were characterized by SEM-EDX, XRD, BET, and DRS analyses and the results showed that Cu-BiOCl possess a unique flower-like nanostructure with narrow band gap (2.53 eV) which enhanced its visible light photocatalytic activity remarkably which was proven by catalyst screening experiments. A detailed experimental study was carried out to investigate the effects of operating parameters on the degradation and decolorization of the dye and from this the optimum values were determined as 0.25 g/L for photocatalyst loading, 100 W for visible light power, 6 for initial pH, 6 mM for initial H2O2 concentration, and temperature of 70 °C. Approximately 91% degradation, 95% decolorization, and 59% TOC reduction were obtained at optimum conditions. The results for the kinetic study showed that the degradation and decolorization reactions are in the pseudo-first order and obey the simplified Langmuir-Hinselwood kinetic model. The activation energies were calculated as 86.54 and 69.39 kJ/mol for degradation and decolorization, respectively.

Catalytic wet air oxidation of Reactive Black 5 in the presence of LaNiO3 perovskite catalyst as a green process for azo dye removal

The removal of textile azo dye, Reactive Black from the aqueous solutions by catalytic wet air oxidation in the presence of LaNiO3 perovskite catalyst has been investigated. The most suitable reaction conditions were determined by testing various the catalyst loadings, reaction temperature and pressure values, and the initial pH of the Reactive Black 5 solutions. The most suitable reaction conditions with 0.61 L/min of air flow rate were found to be 1 g/L of LaNiO3 loading, 50 °C of reaction temperature, 1 atm of reaction pressure, and, pH = 3 for the oxidation of 100 mg/L Reactive Black solutions. Under these conditions the degradation and the decolorization efficiencies were evaluated as 65.4% and 89.6%, respectively. The phytotoxicity analyzes were carried out by using Lepidium sativum. According to the toxicity tests a remarkable decrease in the growth inhibition was achieved by the catalytic wet air oxidation in the presence of LaNiO3 catalyst. The growth inhibition in the untreated and treated dye solutions were calculated as 49.3% and 23.7%, respectively.

Green catalysts for Fenton-like oxidation of Procion Red MX-5B: Influence of the activation method and the reaction parameters on dye removal

ABSTRACT The catalytic activities of the iron catalysts over activated carbon supports prepared by different activation methods in the heterogeneous Fenton-like oxidation of Procion Red MX-5B were investigated. The activated carbons were prepared from walnut shells by applying physical and three chemical activation methods, including HNO3, ZnCl2, and KOH activations to obtain various catalyst supports. KOH-activated carbon catalyst was assessed to be the most efficient one. Under the optimum reaction conditions, 47.5% COD removal, 51.6% degradation, and 91.6% decolorization efficiencies were achieved in the presence of this catalyst. In the kinetic study, the activation energy was evaluated as 47.36 kJ/mol.

FENTON-LIKE OXIDATION OF REACTIVE BLACK 5 IN THE PRESENCE OF LABO3 (B: Fe, Co, Mn, Ni) PEROVSKITE CATALYSTS

The catalytic performances of LaBO 3 (B: Fe, Co, Mn, Ni) perovskite catalysts in Fenton-like oxidation of the textile dye, Reactive Black 5 were compared, and, the optimum reaction conditions were investigated in the presence of the most efficient catalyst. Reactive Black 5 was selected as the model dye due to its complex chemical structure, high water solubility and common usage in the textile industry. The performances of the catalysts in Reactive Black 5 degradation and decolorization were compared by testing different catalyst loadings. According to the catalyst screening experiments, LaFeO 3 showed the highest catalytic performance whereas LaCoO 3 , LaMnO 3 , and, LaNiO 3 were not effective in the degradation and decolorization of Reactive Black 5. A parametric study was carried out in the presence of LaFeO 3 catalyst in order to determine the most suitable reaction conditions. In the parametric study, the effect of catalyst loading, pH and the initial H 2 O 2 concentration were investigated. The initial dye concentration and the reaction temperature were kept constant at 100 ppm and 50 ℃ , respectively. The most suitable reaction conditions were determined as 0.1 g/L of catalyst loading, 3 and 1 mM of H 2 O 2 , and, 96.9% degradation, and complete decolorization were achieved under these conditions.

Green Chemistry and Catalysis

Green chemistry has always been a lively research field. In the time period, the emphasis of catalysis research has significantly shifted and spread from traditional applications in green chemistry. This chapter gives an introduction to overall theme of green chemistry and catalysis emphasizing the concepts such as homogeneous and heterogeneous catalysts, preparation and characterization of catalysts. Readers will find coverage of some important types of green catalysts namely nanocatalysts and perovskite type catalysts with an emphasis on their preparation and characterization. The section on catalyst preparation is concerned with the preparation of bulk catalysts and supported catalysts, with an emphasis on general principles. For the supported catalysts the relation between the method of preparation and the surface chemistry of the support is highlighted. The section on catalyst characterization summarizes the most common techniques in four subtitles: Structural Analysis, Thermal Analysis, Spectroscopic Techniques and Microscopic Techniques.