Application Of Catalytic Ozonation Research Articles

Application of catalytic ozonation using Y zeolite in the elimination of pharmaceuticals in effluents from municipal wastewater treatment plants

Catalytic ozonation using faujasite-type Y zeolite with two different SiO2/Al2O3 molar ratios (60 and 12) was evaluated for the first time in the removal of 25 pharmaceutical compounds (PhCs) present in real effluents from two municipal wastewater treatment plants both located in the Mediterranean coast of Spain. Additionally, control experiments including adsorption and direct ozonation, were conducted to better understand the fundamental aspects of the different individual systems in wastewater samples. Commercial zeolites were used in sodium form (NaY). The results showed that the simultaneous use of ozone and NaY zeolites significantly improved the micropollutants degradation rate, able to degrade 95 % of the total mixture of PhCs within the early 9 min using the zeolite NaY-12 (24.4 mg O3 L−1 consumed), while 12 min of reaction with the zeolite NaY-60 (31 mg O3 L−1 consumed). In the case of individual experiments, ozonation removed 95 % of the total mixture of PhCs after 25 min (46.2 mg O3 L−1 consumed), while the direct adsorption, after 60 min of contact time, eliminated 30 % and 44 % using the NaY-12 and NaY-60 zeolites, respectively. Results showed that the Brønsted acid sites seemed to play an important role in the effectiveness of the treatment with ozone. Finally, the environmental assessment showed that the total risk quotients of pharmaceuticals were reduced between 87 %–99 % after ozonation in the presence of NaY-60 and NaY-12 zeolites. The results of this study demonstrate that catalytic ozonation using NaY zeolites as catalysts is a promising alternative for micropollutant elimination in real-world wastewater matrices.

Facile regulation of Lewis sites and 3D mesoporous channel within Ce-SBA-15 for catalytic ozonation of clofibric acid

The traditional 2D channel of SBA-15 was not favor for the mass transfer and Lewis sites exposures, which restrained its application in catalytic ozonation. Herein, we proposed a facile hydrothermal method for simultaneously regulating pore structure (from 2D to 3D channel) and introducing Ce-based Lewis sites within Ce-SBA-15 with urea (named as Ce-SBA-U) as pH-regulator. pH ascension induced by urea during hydrothermal and phase transition process could weaken the electrostatic interaction between inorganic silicate and surfactant molecules as well as slowed down the hydrolysis and condensation rates of silane, which facilitated the doping of cerium, enlargement of mesoporous sizes and formation of 3D mesoporous channel. Mesoporous sizes of Ce-SBA-U was manipulated by urea dosage and could be enlarged to more than 20 nm, which favored for the mass transfer of ozone and its further activation on Ce(III)-based Lewis sites. The redox cycle of Ce(III)/Ce(IV) could donate electron for surface bonded O3 for the generation of hydroxyl radicals (•OH), superoxide radical (O2•−) and singlet oxygen (1O2). Benefiting from the above features, Ce-SBA-U/O3 process achieved 98.1% clofibric acid (CA) removal and 35.4% TOC removal, which were far beyond those of sole ozonation and Ce-SBA-15/O3 processes. The involved mechanism together with the degradation pathways were exploited by comparative characterizations and experiments. This work could broaden the application of SBA-15 in catalytic ozonation.

Recent Developments in Activated Carbon Catalysts Based on Pore Size Regulation in the Application of Catalytic Ozonation

Due to its highly developed pore structure and large specific surface area, activated carbon is often used as a catalyst or catalyst carrier in catalytic ozonation. Although the pore structure of activated carbon plays a significant role in the treatment of wastewater and the mass transfer of ozone molecules, the effect is complicated and unclear. Because different application scenarios require catalysts with different pore structures, catalysts with appropriate pore structure characteristics should be developed. In this review, we systematically summarized the current adjustment methods for the pore structure of activated carbon, including raw material, carbonization, activation, modification, and loading. Then, based on the brief introduction of the application of activated carbon in catalytic ozonation, the effects of pore structure on catalytic ozonation and mass transfer are reviewed. Furthermore, we proposed that the effect of pore structure is mainly to provide catalytic active sites, promote free radical generation, and reduce mass transfer resistance. Therefore, large external surface area and reasonable pore size distribution are conducive to catalytic ozonation and mass transfer.

Combination of catalytic ozonation and fungal bioremediation for treatment from effluent from the laminate production industry

This study characterized and evaluated the potential of a combination of treatment strategies for the removal of phenolic compounds, color, and ecotoxicity of an effluent generated by a laminated wood industry. The characterization of a sample of the effluent generated by the pine lamination process collected in an industry in the Southwest region of the state of Paraná confirmed the potential impact of the effluent, with emphasis on the high content of phenolic compounds (1,530 ±50 mg/L), color (2,159 ±30 units), significant acute toxicity (63% mortality of microcrustaceans Artemia salina) and low biodegradability (BOD/COD=0.53), which, if eventually released into receiving bodies, can cause irreversible and harmful effects to the aquatic microbiota. The treatment processes studied in this work involved catalytic ozonation mediated by ferrous catalytic material based on steel scale and biological process with Pleurotus Florida fungi, evaluated in an individual way and sequentially integrated as follows: Catalytic ozonation>>biological process and vice-versa. The best results were obtained by applying the sequence "catalytic ozonation>>biological process", which resulted in reductions of 96.2% in soluble lignin concentrations, 93.3% in color units and more than 99% reduction in total phenols, in addition to a low mortality rate of A. salina (≈10%). In the integrated process, the application of catalytic ozonation before the biological process presents greater advantages because of the pre-decomposition process of recalcitrant compounds by the chemical action of catalytic ozonation, which can convert these compounds into biodegradable, facilitating the action of the biological process for the remediation of the effluent.
 Keywords: fungi, ozonation, phenols, wood lamination.

Investigation of the Removal of Several Micropollutants Presenting Different Ozone Reactivities from Natural Potable Water Matrix by the Application of Ozonation with the Use of SiO2 and Al2O3 as Catalysts

The aim of this study was to investigate the correlation between solid materials and micropollutants, aiming to enhance the removal of the latter during the application of the ozonation process. For that purpose, two solid materials (SiO2 and Al2O3) presenting catalytic activity were used for the removal of eight micropollutants from natural potable water, containing them either separately or in a mixture, by ozonation. The studied micropollutants, presenting different physicochemical properties, are atrazine, ibuprofen, p-CBA (ozone-resistant compounds), benzotriazole, caffeine (with moderate ozone reactivity), carbamazepine, fluoxetine, paracetamol (easily oxidized by ozone). The residual concentrations of carbamazepine, paracetamol, and fluoxetine were found to be lower than 5.9 μg/L, 1.2 μg/L, and 15.5 μg/L, respectively, after 1 min of oxidation time in all studied systems. In contrast, benzotriazole and caffeine removal was enhanced by the addition of catalysts; in both cases the best catalyst was SiO2. Regarding the ozone-resistant compounds, both examined materials enhanced the removal of ibuprofen and p-CBA; however, the best was found to be SiO2 and Al2O3, respectively. In contrast, Al2O3 cannot be considered as an effective catalyst for the removal of atrazine, which presents chemical affinity only with SiO2 and for this reason it can be removed to a higher extent by its presence. Similar results were observed in the study of the mixture, although in this system, the residual concentration of all micropollutants was found to be under the detection limit after the application of catalytic ozonation.

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

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.

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

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 the ranges 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.

Catalytic and photocatalytic ozonation with activated carbon as technologies in the removal of aqueous micropollutants

Clopyralid degradation by different treatment processes combining olive stone activated carbon (OSAC), ozone and Solar-Simulated Radiation (SSR) were studied. Firstly, a detailed study of clopyralid adsorption onto OSAC was carried out. The fitted experimental data suggest pseudo-first order kinetics and Freundlich equilibrium isotherm models to describe the process. Secondly, the application of catalytic ozonation was explored. The combination of ozone and OSAC significantly improved the generation of hydroxyl radicals. Moreover, the catalyst showed higher stability and kept efficiency in reuse cycles, if compared to adsorption. Thirdly, the combination of O3, OSAC, and SSR was applied, and different systems were compared, focusing on pH as the main variable. At basic pH (pH = 9), the best removal rate was achieved by O3/OSAC/SSR. Finally, all systems were applied for the treatment of the target compound in an urban wastewater matrix, focusing on the effect of inorganic carbon. The presence of carbonates inhibited only the mineralization rate, not affecting the compound removal.

Permeate flux recovery of ceramic membrane using TiO 2 with catalytic ozonation

Abstract In the present study, ozonation and catalytic ozonation were applied in ceramic membrane ultrafiltration to investigate their effects on membrane fouling. The humic acid solution and titanium dioxide (TiO 2 ) were used as tested water and catalyst, respectively. Controlled operating parameters include ozone gas flow rate, catalyst dosage and ozone dosage. The results reveal that the permeate flux of membrane could be recovered up to 98% of the initial permeate flux when ozone gas was injected into the membrane module at the time of permeate flux decreased to 60% of the initial permeate flux. Two monitored water quality parameters, dissolved organic carbon (DOC) and UV absorbance at 254 nm (UV 254 ) were both removed up to 97% under tested experimental conditions. When TiO 2 was used as the catalyst in catalytic ozonation, the permeate flux of membrane was only recovered up to 93% of the initial permeate flux when catalysts and ozone gas were introduced into the membrane module at the time of permeate flux decreased to 60% of the initial permeate flux. However, the decrease of DOC and UV 254 achieved up to 97% and 100%, respectively. This indicates that the application of catalytic ozonation in the ceramic membrane ultrafiltration system could obtain higher permeate water quality than using ozonation alone. Both ozonation and catalytic ozonation could effectively reduce membrane fouling and maintain stable permeate flux of the tested ceramic membrane system.

Characterization of ferromagnetic sludge-based activated carbon and its application in catalytic ozonation of p-chlorobenzoic acid.

In order to solve the separation problem of powdered sludge-based activated carbon (SAC), a series of novel ferromagnetic sludge-based activated carbons (FMSACs, with different iron content 2.3, 4.3, and 9.5wt%) with a good magnetic separation ability were prepared through co-precipitation method in this study. The structure and physicochemical properties of FMSACs and their catalytic ozonation performance on the removal of p-chlorobenzoic acid (p-CBA) were investigated. The saturation magnetization (Ms) of FMSACs was determined in the range of 0.3674-5.7992emug-1, and experiments confirmed that these FMSACs could be easily separated by magnetic fields. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis indicated that magnetite and maghemite were the main magnetic phases in FMSACs. Comparing with ozonation alone and SAC catalytic ozonation, the presence of 2.3wt% - FMSAC improved the degradation of p-CBA during catalytic ozonation from 44 and 70 to 80%. The tertiary butanol inhibition experiment indicated that FMSACs catalytic ozonation process followed hydroxyl radical reaction mechanism. Furthermore, after six repetitive catalytic ozonation runs, 2.3wt% - FMSAC still showed relatively high catalytic activity for the removal of p-CBA. Consequently, the novel FMSACs with magnetic separation ability and catalytic performance provide a practical pathway for the sludge utilization.

Application of catalytic ozonation in treatment of dye from aquatic solutions

Decomposition of Basic Blue 9 (BB-9) in aqueous solution using ozonation and catalytic ozonation system (O3/granular activated carbon [GAC]) in the bench-scale experiment was investigated. The effect of ozone dose, pH, and GAC contents in removal of BB-9 and biodegradability of effluent such as Biochemical Oxygen Demand (BOD5); Chemical Oxygen Demand (COD), and BOD5/COD were studied. Results show that pH of solution and ozone concentration are significant factors on removal of BB-9; COD and BOD5. Kinetic studies of reactions indicated that reactions followed the first-order kinetics model. The application of GAC as catalyst, in mass concentration of 2 g/l, caused 48% increase in the degradation rate of BB-9. Ozonation process caused an increase in biodegradability of BB-9. However, catalytic ozonation did not have an effect on the biodegradability of the effluent. Acute toxicity tests with Daphnia magna show that this applied treatment method can significantly decrease toxicity of dye in aquatic solutions.

Novel magnetically separable nanomaterials for heterogeneous catalytic ozonation of phenol pollutant: NiFe2O4 and their performances

Magnetic NiFe2O4 nanomaterials were proposed as novel ozonation catalysts for the first time. The samples which were synthesized by the hydrothermal method and the calcined method were dominated as NiFe2O4–H and NiFe2O4–C, respectively. Compared with ozonation alone, the presence of NiFe2O4–H significantly enhanced the degradation of phenol, while NiFe2O4–C was noneffective. The interaction between NiFe2O4–H and ozone was obviously stronger than that in ozonation/NiFe2O4–C. This interaction between catalyst and ozone was proved to be a surface process and played a vital role in the heterogeneous catalytic ozonation. Phosphate revealed significantly inhibitive influence on the decomposition of ozone and the degradation of phenol in ozonation/NiFe2O4. Lewis acid sites were proved as reactive centers for catalytic ozonation in aqueous solution. The results indicated that not only the more surface Lewis acid sites, causing the strong interaction between catalyst and ozone, but also the enhanced interfacial electron transfer lead to the higher catalytic activity of NiFe2O4–H than NiFe2O4–C. Furthermore, the NiFe2O4–H nanocatalyst could be easily and efficiently separated from the reaction mixture with an external magnet, which made it an attractive nanomaterial with prospective application in catalytic ozonation of organic pollutants in water treatment.

Preparation of Manganese Oxide Supported on Activated Carbon and its Application in Catalytic Ozonation of 4-Chlorophenol

Catalyst with manganese oxide highly dispersed on granular activated carbon (MnOx/GAC) was fabricated by impregnating GAC in MnCl2 solution and characterized by several techniques. The performance of manganese catalyst was investigated in catalytic ozonation of 4-chlorophenol in water. Manganese catalyst exhibits better efficiency than the original granular activated carbon, due to the synergic effect between activated carbon and manganese oxide. MnOx/GAC, produced by a simple methodin situ, is promising in catalytic ozonation of refractory organic pollutants in waste water.