جستجوی مقالات مرتبط با کلیدواژه "ازن زنی کاتالیزوری" در نشریات گروه "پزشکی"

Antibiotics are widely used in veterinary and medicine in the last few decades which presence of these compounds has made potential risks for aquatic and terrestrial organisms in the environment. Metronidazole is one of these antibiotics. The purpose of this study was investigation of the efficiency of metronidazole removal from aqueous solutions using a catalytic ozonation process with magnetic nanoparticles of iron oxide doped with silica and titanium dioxide. The sol gel method was used to synthesize Fe3O4@SiO2@TiO2 nanoparticles and its properties were investigated by SEM, XRD and EDX analyzes. The effect of parameters such as pH, catalyst dose, reaction time, contaminant concentration, determining the mineralization and scavenger effect were investigated on the process performance. Changes in metronidazole concentration were determined by HPLC. According to the results of this study, pH =10 and catalyst dose of 3 g /l were obtained as optimum conditions and the removal efficiency increased with increasing of contact time and decreasing in the concentration of metronidazole. Results showed that the removal of metronidazole followed first degree model by this process. Rate of TOC was 86% under optimal operating conditions. Catalytic ozonation process with magnetic nanoparticles of iron oxide doped with silica and titanium dioxide can significantly remove metronidazole and it is an appropriate method for removal of metronidazole.

Background and Presence of natural organic substances in surface water supplies could be harmful and have adverse effects on drinking water treatment due to many practical and hygiene reasons. This study aimed at investigating the efficiency of catalytic ozonation process in removal and mineralization of humic substances in water resources in north of Iran.
Water treatment plants in Gorgan and Sari were studied (2017). First, the concentration of humic substances was measured in water. Then catalytic ozonation process (COP) of the water samples were performed using semi-continuous cylindrical reactor. The effects of some parameters such as reaction time (0-60 min) and catalyst dosage (0 and 3 g/L) on removal efficiency and mineralization of humic substances were investigated. After determining the kinetics constants of reactions, the removal efficiencies were compared between COP and single ozonation process (SOP).
The concentrations of humic substances in water samples in Sari and Gorgan were 15.22 ± 5.39 and 18.62 ± 6.16 mg/L, respectively. The efficiency of removal of humic acid and its mineralization in the COP process under optimal conditions for Naharkhoran, Sari Salim Bahram, and Alangdare water treatment plants, were 100, 84.21, 88.18%, and 100, 83.4, and 78.03%, respectively. The reaction kinetics were first-order and their rates were 2.6, 2.9, and 3.7 folds more than those of the COP process, respectively
Using magnetic activated carbon catalyst coupled with ozonation process, compared to SOP, is 40% more efficient in removal of humic substances. Also, by reducing the ozonation time and the easy recovery of the catalyst and improving the process efficiency it reduces the costs.

Chemical dyes used in the textile wastewater besides having harmful effect on the environment, have carcinogenic and mutagenic effects. Methylene blue has harmful effect on living organisms in short period of exposure. The goal of this study was optimization of the catalytic ozonation process by pumice modified by magnesium nitrate in removal of methylene blue dye based on Taguchi statistical model.
In this experimental study ozonation process was in a batch ozonation reactor. The prepared pumice was crushed and pulverized by standard ASTM (American Society for Testing and Materials) sieves at range of 70 mesh, then modified by magnesium nitrate. Effective factors such as reaction time, initial dye concentration, adsorbent dose, and initial pH at 4 different levels were considered using an L-16 Taguchi method. Residual concentration of contaminants was read using a spectrophotometer at a wavelength of 663 nm. Analysis of data was performed using one- way variance and calculation of S/N (signal- to- noise) rate.
The results showed best conditions for removal dye were at contact time of 15 min, pH of 10, dye concentration of 50 mg/l,and adsorbent dosage of 0.7 g/L and efficiency of dye removal was 98%. Analysis of variance results indicated that the reaction time was the most important variable influencing the dye removal percentage with the contribution value of 51.8% and pH was the least important variable influencing the dye removal with the contribution value of 3.8%
The results showed that ozonation process can be a selective method to reduce the concentration of pollutants in textile wastewater effluent.

Background and Trihalomethanes and haloacetic acids are formed through chlorination of waters containing natural organic matters and pose potential health problems. So, it is necessary to remove humic acid as the most significant natural organic matter in water. The aim of this study was to evaluate the efficiency of catalytic ozonation in removal of humic acid in presence of local green and red montmorillonite.
Green and red soils were collected from Sarcham area in Ardabil, Iran and used as catalysts after cleaning up. The variables in this study included initial pH of the solution, catalyst dosage, reaction time, and initial concentration of the pollutant.
The efficiency of catalytic ozonation process increased by increase in contact time, pH, and doses of catalysts and also by decrease in initial concentration of humic acid. In COP process, 100% removal of humic acid (10mg/l) was achieved at natural pH in 15 and 20 min in presence of green and red soils, respectively. Compared with conventional ozonation, presence of radical scavengers such as nitrate, chloride, sulphate and carbonate at high concentrations were found to have minor effects on reducing the efficiency of catalytic ozonation process.
Based on this study, green and red soils highly increase the efficiency of catalytic ozonation process. Due to the low cost and availability of these soils, they can be used as catalysts to remove humic acid in catalytic ozonation process or other similar processes.

Background and Catechol is a ring form organic compound with high toxicity that is used in petrochemical, pharmaceutical and manufacturing of pesticide. It has adverse effects on human and environmental health if discharged into the environment. The purpose of this study was removal of catechol using catalytic ozonation using core-shell magnetic nanoparticles of iron oxide doped with silica and titanium dioxide from aqueous solution.
We conducted a basic-applied study in which magnetic nanoparticle Fe3O4@SiO2@TiO2 was synthesized using sol-gel method. To determine the characteristics of nanoparticle, XRD, SEM and EDX tests were used. Then effect of different parameters on removal efficiency were investigated. These included solution pH (2-10), reaction time (0-60 min), dose of catalyst (0.2-3 gr/L), initial concentration of catechol (50-1000 mg/L), recycled test (7 times), and determining the mineralization and scavenger effect. The residual concentration of catechol was measured using high-performance liquid chromatography at 275 nm.
The optimal pH for the catalytic ozonation process was 8. The maximum efficiency of the process in optimal conditions (catechol concentration 1000 mg/l, pH=8, catalyst dosage 3 gr/L and dose of ozone 0.38 gr/hr) was 100% after 60 minutes of contact time. Kinetics of degradation of catechol followed first degree model. After reaction time the amount of mineralization was 91.5%. Reusability of catalyst was done 7 times and its efficiency decreased by about 4%. Scavenger (1 gr/l tert-butanol) decreased removal of catechol by 4.16%.
The catalytic ozonation process using Fe3O4@SiO2@TiO2 nanoparticles in an alkaline pH was found to be capable of eliminating high concentrations of catechol effectively.

Metronidazole, as one of the most widely used antibiotics in the world, in addition to various benefits, has significant adverse effects on the environment and animals. The catalytic ozonation process is one of the most successful methods for antibiotics removal. However, it should be noted that this process, like other oxidation processes, has some byproducts that can be toxic in the process effluent.
Under optimum conditions for catalytic ozonation in the presence of MgO nanoparticles, 1 sample was obtained from a reactor after 10 minutes of ozonation. The sample was analyzed by gas chromatography–mass spectrometry (GS-MS) and the intermediates were identified. The mineralization rate was determined using TOC analysis and the toxicity changes were calculated through bioassay with Daphnia magna.
Findings: In the present study, 4 compositions were identified as oxidation intermediates. The mineralization rate was about 93.5% and the 48-hour toxicity unit decreased from 1.24 in the influent to 0.32 in the effluent.
A high mineralization rate was obtained in the process. Nevertheless, it was not complete, and thus, the influent solution was converted from toxic to slightly toxic. In conclusion, we can say that catalytic ozonation process in the presence of MgO nanoparticles can be acceptable for metronidazole removal.

Antibiotics can cause negative impacts on animals and bacterial resistance by entering to the environment. Catalytic ozonation process is a method for increasing the efficiency of the simple ozonation. This study evaluated the efficiency of catalytic ozonation process with activated carbon modified with MgO to remove metronidazole from aqueous solutions in a fluidized bed reactor.
Catalytic ozonation experiments were performed in a fluidized bed reactor. Impact of pH, reaction time, catalyst dosage, initial concentration, radical scavengers and hydroxyl radicals was found. The degradation kinetic of metronidazole was determined as well as FTIR spectra of the catalysts. The concentration change of metronidazole was determined by HPLC.
The results showed that the catalyst prepared increases metronidazole decomposition rate as high as 7.32 times, compared to conventional ozonation. The optimum pH of 10, the optimal dose of 1.5 g/L of catalyst and the optimum time of 30 min were determined. The results of radical scavengers’ effect showed the main reactions of metronidazole decomposition are on the catalyst surface.
The results showed that, due to the high performance activated carbon coated with MgO in catalytic ozonation process, increased removal of metronidazole, compared with simple ozonation, and easy access to raw materials, the use of these catalysts in ozonation process are recommended to increase efficiency and accelerate the metronidazole decomposition reaction and similar compounds.

Xylene is a volatile organic compound That cause central nervous system disorder and suspected cancer. Concern of occupational exposure to volatile organic compounds (VOCs) has been increasing. Thus before being discharged to the environment, it must be treated from polluted air stream.
The research study is of the experimental type and was carried out on a laboratory scale. The experimental equipmen including of an air compressor, silicagel filters and activated charcoal, Syringe Pump, an ozone generation and a fixed bed reactor. The sampling, xylene analyzing in samples were done with 1501 Niosh Manual Analytic Method by GC equipped with FID detector The performance of catalytic ozonation process was compared with that of single adsorption and ozonation in removal of several concentration of xylene under the similar experimental conditions.
The results indicated that the catalytic ozonation concentration increased from 50 to 200 ppm, absorption break point and removal of xylene from hybrid reactor decreased from 12 to 8 h, while this time was between 9 and 5 h for pumice. When pumice and ozone come together, their synergistic effects increased on xylene degradation. Also the efficiency of absorbent decreased with the concentration increase of xylene.
With regard to high efficiency of catalytic ozonation process and increasing the xylene removal, the catalytic ozonation process is suggested as a promising and alternative technology for elimination of VOCs from the polluted air stream.

Background and Conventional treatment processes do not have good efficiency in degradation and removal of antibiotics from aqueous environments, therefore, using advanced oxidation processes seems to be necessary. The aim of this study was to evaluate the performance of catalytic ozonation for degradation of cefazolin from aqueous environments and the effect of various parameters on the performance of this process. In this experimental study after applying the process, the effect of different parameters were measured including pH (2-10), initial concentration of cefazolin (5-45 mg/L), catalyst dose (0.25-1 gr/L), ozone concentrations (1-5 mg/L.min), TBA concentration (0. 2mg/L) as a radical scavenger, the synergistic effect of the parameters, and reducing COD and TOC. Cefazolin concentrations and COD levels were measured by a spectrophotometer after the process and TOC was measured by TOC analyzer. Then the SEM images, BET analysis of nanoparticles, and XRD were prepared. The optimum condition for the highest efficacy of the process was found to be pH 8, catalyst dose 0.5 gr/L, O3 concentration 5 mg/L.min and cefazolin concentration 5 mg/L. At this optimal condition the efficiency of process was 92.01%. In presence of TBA, the efficiency of process reduced. The efficiency of process in COD and TOC removal was 55% and 42%, respectively. The results showed that the process conducted in this study was useful in degradation and mineralization of cefazolin, and can be used in treatment of wastewater containing pollutants. One of the main features of this process is that it does not produce sludge and by-products. Removal of COD and TOC needs more reaction time.

The presence of phenol in effluents may cause risk to human health. By Taguchi statistical model, the process can be optimized by certain number of experiments. The aim of this study was optimization of catalytic ozonation process in removal of phenol from aqueous environments by Nano Fe / MgO with Taguchi statistical model. In this experimental study, experiment design was set based on the statistical model. Parameters such as pH (3, 5, 9, and 11), initial concentration of pollutant (500, 1000, 1500, and 2000 mg/L), reaction time (10, 20, 30, and 40 min) and catalytic dose (0.1, 0.2, 0.3 and 0.4 g/L) in 4 layers and 4 levels were investigated. Data were analyzed with Minitab ver.16 software. Residual concentration of phenol was measured according to standard method book. The results showed that, efficiency of phenol removal depends on various operational parameters. The optimum conditions of phenol removal was obtained at reaction time=30 min, pH=5, the phenol initial concentration of 1000 mg/L and catalyst dose of 0.1 g/L. Among the factors investigated; initial concentration of phenol has the maximum effect (69.5%) and reaction time the minimum (3.2%) effect in optimum conditions. S/N ratio of 39.39 was estimated at optimum conditions. By using Taguchi statistical model, phenol removal was optimized in certain number of experiments. Ozonation process has high capability in phenol removal.

Background and Chemical dyes are widely used in textile industries and have harmful effects on the environment. They also contain carcinogenic and mutagenic substances. The goal of this study was optimization of the catalytic ozonation process using bone char ash modified by magnesium oxide in removal of reactive black 5dye from textile wastewater based on Taguchi design. In this study ozonation was performed in a batch ozonation reactor. In order to remove the dyes, Bone char ash (BCA) was modified by magnesium oxide. The effect of various parameters such as reaction time, initial dye concentration, adsorbent dose, and initial pH at 4 different levels were investigated using an L-16 Taguchi method. Analysis and interpretation of data was done using Minitab V.16. The optimum conditions for removal of dye were found to be contact time of 20 min, pH 8, dye concentration of 50 mg/l, adsorbent dosage of 0.3 g/L. The efficiency of dye removal was 98% and COD removal was 85%. Analysis of variance indicated that the dye concentration was the most important variable influencing the dye removal percentage (51.8%) and pH was the least influencing variable (3.8%) in removal of dye. The results showed that ozonation process was an effective method in reducing the concentration of pollutants in textile wastewater effluent.

Synthetic dyes especially azo dyes are، nowadays، used by the majority of industries for dyeing various materials. In addition to producing color in receiving streams، these dyes may have adverse health effects on human. This study was carried out to investigate the catalytic ozonation with marble powder in the removal of reactive black 5. Marble powder was supplied from Hamadan workshops stonemason. The powder was grinded and sieved to the desired particle size using standard mesh 40. Batch degradation and mineralization studies were performed as a function of pH، adsorbent dose and the influence of catalytic potential of marble powder. Residual dye concentrations were spectrophotometrically measured at 597 nm. In order to comply with ethical principles، in this study، all entries with the references noted. Reduction of 98% of reactive black 5 was observed when 0. 3g catalyst was employed per liter of solution during 20 minutes at pH 10 and in the presence of 50 mg dye. The catalytic potential of marble was 54%. Results from this study demonstrated the potential utility of marble powder as an effective catalyst in catalytic ozonation process.

Dyes are widely used in different industries and consequently are disposed through different industrial effluents into the environment. Chronic and/or acute effects of the chemicals on microorganisms have been documented. Dyes may absorb and reflect the entering sun lights into the water and thereby decrease the algal photosynthesis. The later in turn can affect the food chain seriously. The aim of this study was، therefore، to use MgO nanoparticles as catalyst in heterogenic catalytic ozonation process (COP) for reactive red 120 dye removal (decolorization) from synthetic wastewater. MgO nanoparticles were produced by sol-gel method. The influences of several operational parameters including solution pH، reaction time، MgO dosage and initial dye concentration on removal (decolorization) efficiency were evaluated. The optimum pH and MgO dosage for COP were determined as 10 and 3 g/L، respectively. Decolorization of 500 mg/L of dye was almost complete after 12 min under achieved optimum conditions. MgO nanocrystals markedly affected the COP and enhanced the dye removal efficiency by approximately 49% compared with the sole ozonation process. Higher O3 decomposition in presence a small amounts of catalyst and alkaline pH increases the radical production which in turn improves the decolorization efficiency. Increasing the initial concentration of dye deteriorated the removal efficiency; however، this can be compensated by increasing the ozonation rate.

The widespread use of toluene and its consequent adverse effects on health and specially its chronic effects on the central nervous system has resulted in many studies being carried out on the methods that can control and reduce toluene vapors in the airflow. The objective of this study is to assess the effectiveness of the catalytic ozonation process in the removal of toluene from the airflow. The present study is of the experimental type and was carried out on a laboratory scale. The experimental equipment consisted of an air pump, an injection pump, an ozone generator, a humidity generating system, a mixing chamber, a rotameter, and a glass reactor with a length of 25 cm and an internal diameter of 2 cm. Varying concentrations of toluene were constantly exposed to the process of catalytic ozonation to the activated carbon and activated carbon covered in magnesium nitrate while inducing changes in variables such as reaction time, ozone dosage, and level of humidity. Different concentrations of toluene were measured before and after exposure to the treatment process. The data were analyzed using the SPSS Win 16 and such statistical techniques and methods as descriptive and inferential statistics and three-way ANOVA were utilized. The findings indicated that the toluene removal rates were much higher in the catalytic ozonation process when activated carbon covered in magnesium nitrate was used than when pure activated carbon was used. This issue can be deduced from the fact that the time necessary for toluene to appear at the exit point of the reactor when using activated carbon is 50 hours, while this time in case of use of activated carbon covered in magnesium nitrate is 115 hours. The findings also showed that the three variables of reaction time, ozone dosage, and relative humidity had a positive effect on the process, so that increasing the amounts of these three variables led to an enhancement of the removal system. Given the considerable enhancement of the toluene removal rates as a result of concomitant use of activated carbon and magnesium nitrate in the catalytic ozonation process, it can be concluded that activated carbon covered in magnesium nitrate is an appropriate method in the removal of VOCs from the airflow.

Pharmaceutical products، particularly antibiotics، due to their cumulative and inappropriate effects and creating drug resistances، as inevitably pollutants، have been created a major concern in environmental control. Metronidazole (MTN) is one of these antibiotics. Hence، the aim of this study was investigation of MTN removal efficiency by catalytic ozonation process (COP) in presence of produced magnesium oxide nanocrystals as catalyst. The influences of several operational factors for their effects on removal were evaluated، including solution pH (3-12)، reaction time، MgO dosage (0. 25-4 g/L) and initial MTN concentration (1-40 mg/L). Also degradation kinetic، biodegradability improvement and mineralization rate were studied for the COP. For degradation kinetic the best compatibility was with pseudo-second order (liner type II) model. The optimum pH and MgO dosage for COP were determined to be 10 and 0. 25 g/L، respectively. Under optimum condition the complete removal of 40 mg/L MTN solution was observed after 20 min. The results illustrate that MgO nanocrystals markedly accelerated the MTN degradation in and the COP significantly increased BOD5/COD ratio and caused 94% MTN mineralization.

Dye removal from industrial wastewater has been considered as one of the most environmental issues. Recently، new methods of treatment such as catalytic ozonation have been used to increase dye removal efficiency. So، the efficiency of catalytic ozonation by copper coated zeolite as a catalyst in the removal of Reactive Red 198 was investigated. In order to remove dye، the zeolite granules were modified by CuSO4. The heterogenous catalytic ozona-tion experiments were carried out to deter-mine the effect of pH، contact time، initial dye concentration، catalyst dose and radical scavengering in a semi-batch reactor. Sca-nning Electron Microscope (SEM)، X-ray Diffraction (XRD)، X-ray Fluorescence (XRF)، Adsorption/Desorption Porosimetry (BET) analyses were used to determine the structural properties، chemical compounds، specific surface area and morphological characteristic of zeolite and copper coated zeolite. Also catalytic ozonation process (COP) removal in both catalytic and sole ozonation was measured. The results showed that in cat-alytic ozonation، the removal efficiency of the dye increased in proportion to the increasing of pH، contact time، catalyst dose. Conversely، with the increasing of the initial concentrations of dye from 100 to 500 mg/L، removal efficiency decreased from 92% to 68% in catalytic ozonation. Furthermore، in the presence of radical scavenger، no considerable decrease was observed in catalytic ozonation. Also COD experiments showed 20% and 45% incr-eases in the sole ozonation and catalytic ozonation، respectively. Discussion & Due to the low cost، availability and high performance of zeolite as a catalyst support، and also with regard to the advantages of heterogenous systems compared with homogenous sys-tem، using of copper coated zeolite in cata-lytic ozonation processes for the removal of different pollutants is suggested.

As dyes are the most important pollutants of many industrial wastewaters. A large amount of Reactive Black 5 enters the environment in Iran because of the use of this dye in Iran's textile industries, so the goal of this study was to survey the Catalytic Ozonation process with Bone Char in removal of Reactive Black 5 dye from synthetic wastewater. Methods and Materials: In this experimental study Bone Char(BC) was prepared under laboratory conditions using of electrical furnace at 800°C for 2h.The prepared BC was crushed and pulverized by standard ASTM sieves at range of 10 to16 mesh. The chemical composition and solid structure of BC was analyzed using X-ray diffraction and measurement of the surface area was carried out by N2 gas adsorption via BET(Brouner Emmet Teller) isotherm. The concentration of dye was measured by photometric method at 600nm wave length. A set with 4 L/min inlet flow rate was used for ozonating to produce 5 gram ozone at hour. As results showed predominant composition of BC is CaO. The BC surface area is 92.5m2/g. The results of this study showed that increasing of initial dye concentration and pH would lead to decrease of removal of RB5 dye. All of RB5 dye was removed at lapse of 40 minute. Bone char is a cheap and suitable catalyst that can be used in water and wastewater treatment. Based on optimum pH=10 found for the removal of RB5 and the fact that many of textile industrial wastewaters have an alkaline pH, this process can be suitable for the removal of dyes from these industrial. wastewaters.

Backgrounds and Volatile organic compounds (VOCs) are one of the common groups of contaminants encountered in the industrial activities, emitted through air stream into the atmosphere. To prevent the human and environmental health from the adverse effects of VOCs, air streams containing VOCs need to be treated before discharging to environment. This study was aimed at investigating the catalytic ozonation process for removing xylene from a contaminated air stream. In the present work, a bench scale experimental setup was constructed and used for catalytic ozonation of xylene. The performance of catalytic ozonation process was compared with that of single adsorption and ozonation in removal of several concentration of xylene under the similar experimental conditions. The results indicated that the efficiency of catalytic ozonation was higher than that of single adsorption and ozonation in removal of xylene. The emerging time and elimination capacity of xylene for inlet concentration of 300 ppm was 1.4 and 5.8 times of those in adsorption system. The activated carbon acted as catalyst in the presence of ozone and thus attaining the synergistic effect for xylene degradation. catalytic ozonation process is an efficient technique the treatment of air streams containing high concentrations of xylene. The adsorption systems can also be simply retrofitted to catalytic ozonation process and thereby improving their performance for treating VOCs.

Background and aimsThe catalytic ozonation is an efficient process for the degradation of volatile organic compounds from contaminated air stream. This study was aimed at investigating the efficacy of catalytic ozonation process in removal of xylene from the polluted air stream and the influence of retention time (gas flow rate), inlet ozone dose and relative humidity on this performanceMethodsthe catalytic ozonation of xylene was conducted using a bench scale set-up consisted of a syringe pump,an air pump, an ozone generator, and a glass reactor packed with activated carbon. Several experimental run was defined to investigate the influence of the selectedoperational variables.ResultsThe results indicated that the efficiency of catalytic ozonation was greater than that of single adsorption in removal of xylene under similar inlet concentration and relative humidity. We found a significant catalytic effect for activated carbon when used in combination with ozonation process, leading to improvement of xylene removal percentage. In addition, the elimination capacity of the system improved with the increase of inlet ozone dose as well as gas flow rate. The relative humidity showed a positive effect of the xylene removal at the range of 5 to 50%, while the higher humidity (more than 50%) resulted in reduction of the performance.ConclusionThe findings of the present work revealed that the catalytic ozonation process can be an efficient technique for treating the air streams containing industrial concentrations of xylene. Furthermore, there is a practical potential to retrofit the present adsorption systems intothe catalytic ozonation simply by coupling them with the ozonation system. the catalytic ozonation of xylene was conducted using a bench scale set-up consisted of a syringe pump,an air pump, an ozone generator, and a glass reactor packed with activated carbon. Several experimental run was defined to investigate the influence of the selected operational variables.