scholarly journals Transition Metal Ions as Ozonation Catalysts: An Alternative Process of Heterogeneous Catalytic Ozonation

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1091
Author(s):  
Savvina Psaltou ◽  
Konstantina Sioumpoura ◽  
Efthimia Kaprara ◽  
Manassis Mitrakas ◽  
Anastasios Zouboulis
Keyword(s):  
Catalytic Activity ◽  
Metal Ions ◽  
Natural Water ◽  
Transition Metal Ions ◽  
Catalytic Ozonation ◽  
Experimental Conditions ◽  
Chlorobenzoic Acid ◽  
Heterogeneous Catalytic ◽  
Water Matrix ◽  
Phosphate Ions

The aim of this study is to elucidate the mechanism of micropollutants’ removal in drinking water by the application of catalytic ozonation, using transition metals as appropriate catalysts. For that purpose, the degradation of 500 μg/L of p-chlorobenzoic acid (p-CBA) and benzotriazole with the addition of 2 mg/L of ozone in the presence of 1 mg/L of Co(II) or Fe(II) and at pH 7.8 were examined. It was found that in distilled water experiments, both metal ions can be characterized as catalysts, enhancing the ozonation process; however, in the natural water matrix, only iron presented higher removal rates of examined organic pollutants, when compared to single ozonation. The metal ions present catalytic activity, when they can form precipitates, hence converting the initially homogeneous process of catalytic ozonation towards a heterogeneous one. However, when 2 mg/L of ozone was applied in natural water experiments, Co(II)—unlike Fe(II)—could not be oxidized into its trivalent form, hence it cannot precipitate as Co(OH)3. Therefore, under these experimental conditions, this metal was not found to present any catalytic activity. Nevertheless, the addition of phosphates (PO43−) in concentrations higher than 100 mg/L can increase the oxidation ability of the Co(II)/O3 system, due to the resulting sufficient formation of Co3(PO4)2 precipitates. Although cobalt can enhance the •OH production (and therefore, the ozonation procedure) under these conditions, the relatively highly added concentration of phosphate ions makes the treated water non-potable, resulting in the application of further treatment to remove the excess phosphates. Therefore, only Fe(II) can be considered as a sufficient catalyst to enhance the ozonation processes.

scholarly journals The Effect of Thermal Treatment on the Physicochemical Properties of Minerals Applied to Heterogeneous Catalytic Ozonation

2020 ◽  
Vol 12 (24) ◽  
pp. 10503
Author(s):  
Savvina Psaltou ◽  
Efthimia Kaprara ◽  
Kyriaki Kalaitzidou ◽  
Manassis Mitrakas ◽  
Anastasios Zouboulis
Keyword(s):  
Catalytic Activity ◽  
Thermal Treatment ◽  
Physicochemical Properties ◽  
Hydroxyl Radicals ◽  
Ph Value ◽  
Catalytic Ozonation ◽  
Point Of Zero Charge ◽  
Chlorobenzoic Acid ◽  
Positive Effects ◽  
Heterogeneous Catalytic

In order to enhance the efficiency of heterogeneous catalytic ozonation, the effect of thermal treatment on three commonly used and inexpensive minerals, i.e., zeolite, talc and kaolin (clay), which present different physicochemical properties as potential catalysts, has been examined for the removal of para-chlorobenzoic acid (p-CBA). p-CBA is considered a typical micro-pollutant, usually serving as an indicator (model compound) to evaluate the production of hydroxyl radicals in ozonation systems. The catalytic activity of selected solid catalysts was studied for different pH values (6, 7 and 8) and different temperatures (15 °C, 25 °C and 35 °C). The mechanism of radicals’ production was also verified by the addition of tert-butyl alcohol (TBA). The respective thermal behavior study showed that the point of zero charge (PZC) of these minerals increased with the increase of applied treatment temperature, as it removed crystalline water and hydroxyls, thus improving their hydrophobicity. Circa-neutral surface charge and the presence of hydrophobicity were found to favor the affinity of ozone with solid/catalytic surfaces and the subsequent production of hydroxyl radicals. Therefore, zeolite and talc, presenting PZC 7.2 and 6.5 respectively, showed higher catalytic activity after thermal treatment, while kaolin with PZC equal to 3.1 showed zero to moderate catalytic efficiency. The degradation level of p-CBA by oxidation was favored at 25 °C, while the pH value exerted positive effects when it was increased up to 8.

The effect of partial exchange of sulphonated macroporous styrene-divinylbenzene copolymers for different ions on their catalytic activity

1981 ◽  
Vol 46 (10) ◽  
pp. 2354-2363 ◽  
Author(s):  
Svatomír Kmošták ◽  
Karel Setínek
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Metal Ions ◽  
Gas Phase ◽  
Transition Metal Ions ◽  
Exchange Capacity ◽  
Total Exchange Capacity ◽  
Styrene Divinylbenzene ◽  
Na Ions ◽  
Type Of Transition

The catalytic activity of sulphonated macroporous styrene-divinylbenzene copolymers, the exchange capacity of which was neutralized from 30, 50 and 80% by Fe(III) ions and from 30% by Na ions and that of Wofatit Y-37 ion exchanger neutralized from 10% of its total exchange capacity by several transition metal ions and by sodium has been studied in isomerisation of cyclohexene and dehydration of 1-propanol in the gas phase at 130 °C. It was demonstrated that in both reactions transition metal ions exhibit additional effect to the expected neutralization of the polymer acid groups. In the case of cyclohexene isomerization, this effect depends on the degree of crosslinking of polymer mass of the catalyst. Such dependence has not been, however, observed in dehydration of 1-propanol. The type of transition metal ions did not exhibit any significant effect on the catalytic activity of the polymer catalysts studied.

Efficient Catalytic Activity of Transition Metal Ions in Vilsmeier-Haack Reactions with Acetophenones

2013 ◽  
Vol 45 (11) ◽  
pp. 721-733 ◽  
Author(s):  
F. Aneesa ◽  
K. C. Rajanna ◽  
M. Venkateswarlu ◽  
K. Rajendar Reddy ◽  
Y. Arun Kumar
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Metal Ions ◽  
Transition Metal Ions

Fe3O4@TiO2preparation and catalytic activity in heterogeneous photocatalytic and ozonation processes

2015 ◽  
Vol 5 (2) ◽  
pp. 1143-1152 ◽  
Author(s):  
L. Ciccotti ◽  
L. A. S. do Vale ◽  
T. L. R. Hewer ◽  
R. S. Freire
Keyword(s):  
Catalytic Activity ◽  
Magnetic Nanoparticle ◽  
Catalytic Ozonation ◽  
Systematic Evaluation ◽  
Hybrid Catalyst ◽  
Heterogeneous Catalytic ◽  
Nanoparticle Preparation ◽  
Ozonation Process

Systematic evaluation of experimental variables in magnetic nanoparticle preparation and hybrid catalyst application in the heterogeneous catalytic ozonation process.

scholarly journals Comparative study on heterogeneous and homogeneous catalytic ozonation efficiency in micropollutants' removal

2021 ◽  
Author(s):  
S. Psaltou ◽  
E. Kaprara ◽  
M. Mitrakas ◽  
A. Zouboulis
Keyword(s):  
Catalytic Activity ◽  
Organic Compounds ◽  
Hydroxyl Radicals ◽  
Ozone Concentration ◽  
Oxidation Reaction ◽  
Physicochemical Characteristics ◽  
Catalytic Ozonation ◽  
Experimental Conditions ◽  
Kinetic Rate ◽  
Kinetic Rate Constants

Abstract Catalytic ozonation was applied for the removal of small concentrations (4 μM) of micropollutants benzotriazole, carbamazepine, p-CBA from aqueous solutions at pH 7. These compounds present different physicochemical characteristics and different kinetic rate constants, when reacting with ozone or hydroxyl radicals in range of <0.15–3 × 105, 5.2 × 109, and 8.8 × 109 M−1s−1, respectively. Calcite was used as heterogeneous catalyst and its catalytic activity evaluated, by applying (and optimized) different experimental conditions (i.e., pH, temperature, ozone concentration), concerning the removal efficiency of p-CBA. Study of micropollutants' removal showed all examined organic compounds can be sufficiently removed by application of catalytic ozonation either by use of calcite, or by presence of Co(II) or Fe(II) (applied as homogeneous catalysts), while the optimum catalyst between them was found to be calcite. Carbamazepine with kO3 = 3 × 105 M−1s−1 can be easily removed, even by application of single ozonation, while benzotriazole and p-CBA resulted in 50% and 68.2% higher removal after application of catalytic ozonation within 3 min of oxidation reaction, due to acceleration of hydroxyl radicals' production by presence of calcite in the ozonation system. The contribution of hydroxyl radicals in removal of all three micropollutants was evaluated by extraction of Rct and f•OH parameters.

scholarly journals New Insight into the Interplay of Method of Deposition, Chemical State of Pd, Oxygen Storage Capability and Catalytic Activity of Pd-Containing Perovskite Catalysts for Combustion of Methane

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1399
Author(s):  
Silva Stanchovska ◽  
Georgy Ivanov ◽  
Sonya Harizanova ◽  
Krasimir Tenchev ◽  
Ekaterina Zhecheva ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Metal Ions ◽  
Supported Catalysts ◽  
Transition Metal Ions ◽  
Chemical State ◽  
Oxygen Storage ◽  
Heterogeneous Model ◽  
Wet Impregnation ◽  
Insight Into

Elaboration of Pd-supported catalysts for catalytic combustion is, nowadays, considered as an imperative task to reduce the emissions of methane. This study provides new insight into the method of deposition, chemical state of Pd and oxygen storage capability of transition metal ions and their effects on the catalytic reactivity of supported catalysts for the combustion of methane. The catalyst with nominal composition La(Co0.8Ni0.1Fe0.1)0.85Pd0.15O3 was supported on SiO2-modified/γ-alumina using two synthetic procedures: (i) aerosol assisted chemical vapor deposition (U-AACVD) and (ii) wet impregnation (Imp). A comparative analysis shows that a higher catalytic activity is established for supported catalyst obtained by wet impregnation, where the PdO-like phase is well dispersed and the transition metal ions display a high oxygen storage capability. The reaction pathway over both catalysts proceeds most probably through Mars–van Krevelen mechanism. The supported catalysts are thermally stable when they are aged at 505 °C for 120 h in air containing 1.2 vol.% water vapor. Furthermore, the experimentally obtained data on La(Co0.8Ni0.1Fe0.1)0.85Pd0.15O3—based catalyst, supported on monolithic substrate VDM®Aluchrom Y Hf are simulated by using a two-dimensional heterogeneous model for monolithic reactor in order to predict the performance of an industrial catalytic reactor for abatement of methane emissions.

Heterogeneous catalytic ozonation of 2, 4-dinitrophenol in aqueous solution by magnetic carbonaceous nanocomposite: catalytic activity and mechanism

2015 ◽  
Vol 57 (43) ◽  
pp. 20447-20456 ◽  
Author(s):  
Yousef Dadban Shahamat ◽  
Mahdi Sadeghi ◽  
Ali Shahryari ◽  
Niloofar Okhovat ◽  
Farshad Bahrami Asl ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Catalytic Activity ◽  
Catalytic Ozonation ◽  
Heterogeneous Catalytic
Sign in / Sign up

Export Citation Format

Share Document