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1.
Atrazine is one of the most frequently identified pesticides in Europe. Current European standards stipulate that the maximum contaminant level (MCL) for the individual pesticide is 100 ng/L. This regulation stresses the need for a low-cost and effective treatment system. Adsorption is one promising solution, but, in general, breakthrough of the granular activated carbon filter occurs rapidly. Recent research has shown that ozonation alone utilized according to the usual practical conditions removes atrazine only poorly (15-25%). High oxidation reaction rates of the hydroxyl free radical suggest a better, removal method by combinations of O 3/H 2O 2. The feasibility of such a combination has been evaluated in this present study. 相似文献
2.
The oxidative removal of a diverse group of trace organic contaminants from surface water and wastewater was evaluated using ozone (O 3) and O 3 combined with hydrogen peroxide (O 3/H 2O 2). Target compounds included estrogenic and androgenic steroids, pharmaceuticals, pesticides, and industrial chemicals. Bench- and pilot- scale experiments were conducted with surface water spiked with the target compounds and wastewater effluent containing ambient concentrations of target compounds. Full-scale water treatment plants were sampled before and after ozonation to determine if bench- and pilot-scale results accurately predict full-scale removal. In both drinking water and wastewater experiments, the majority of target compounds were removed by greater than 90% at O 3 exposures commonly used for disinfection. Atrazine, iopromide, meprobamate, and tris-chloroethylphosphate (TCEP) were the most recalcitrant compounds to oxidize using O 3, with removals generally less than 50%. The addition of H 2O 2 for advanced oxidation was of little benefit for contaminant removal as compared to O 3 alone. O 3/H 2O 2 provided a marginal increase in the removal of dilantin, diazepam, DEET, iopromide, and meprobamate, while decreasing the removal efficacy of pentoxifylline, caffeine, testosterone, progesterone, and androstenedione. In wastewater experiments, O 3 and O 3/H 2O 2 were shown to remove in vitro estrogenicity. Collectively, these data provide evidence that O 3 is a highly effective oxidant for removing the majority of trace organic contaminants from water. 相似文献
3.
Fenton-driven regeneration of spent granular activated carbon (GAC) can be used to regenerate organic contaminant-spent GAC. In this study, the effects of GAC particle size (>2 mm to <0.35 mm) and acid pre-treatment of GAC on Fenton-driven oxidation of methyl- tert-butyl ether (MTBE)-spent GAC were evaluated. Iron (Fe) was amended to the GAC using two methods: (1) untreated—where GAC was amended with a concentrated solution of ferrous sulfate and (2) acid pre-treatment—where GAC was amended with acid followed by sequential applications of a dilute ferrous sulfate solution. Subsequently, MTBE was amended to the GAC, followed by oxidative treatments with H 2O 2. H 2O 2 reaction and MTBE oxidation were inversely correlated with GAC particle size and were attributed to shorter intraparticle diffusion transport distances for both H 2O 2 and MTBE. Image analysis of the GAC cross-sections (i.e., prepared thin sections) revealed that the Fe amended to the GAC extended to the center of the GAC particles. Fe accumulated at higher levels on the periphery of the untreated GAC but Fe dispersal was more uniform in the acid pre-treated GAC. In the acid pre-treated GAC, conditions for MTBE oxidation were favorable and greater levels of MTBE oxidation were measured for all particle size fractions tested. Modeling and critical analysis of H 2O 2 diffusive transport and reaction indicated limited H 2O 2 penetration into large GAC particles which contributed to a decline in MTBE removal. Residual MTBE remaining on the GAC limited the quantity of MTBE that could be re-adsorbed, but no reduction in MTBE sorption capacity resulted from oxidative treatments. 相似文献
4.
The objective of the presented study was to test various oxidation processes with the aim being to reduce the concentration and toxicity of biocide wastewater from a Slovenian phytopharmaceutical factory. Laboratory-scale experiments employing two AOP processes – ozonation (O 3) and peroxone (H 2O 2/O 3) – were applied to reduce the concentration of the active components involved, i.e., methylisothiazolone (MI), chloromethylisothiazolone (CMI) and dichloromethylisothiazolone (DCMI). The reduction of the biocide wastewater load for the performed oxidation processes was evaluated using ecological parameters. The H 2O 2/O 3 oxidation procedure using an O 3 flow rate of 1g/L h, at a pH value of 10 and with the addition of 5 ml of H 2O 2 (0.3 M) proved to be the most effective treatment. The toxicity of the biocide-load wastewater with an initial EC 50 = 0.38%, decreased to EC 50 (24h) >100% and EC 50 (48h) = 76%. 相似文献
5.
The authors monitored hydrogen peroxide (H 2O 2), ozone (O 3), and apparent hydroxyl radical (OH·) concentrations in the liquid phase, along with gas phase ozone when operating an advanced oxidation (AO) system that included H 2O 2, O 3, sonication, and underwater plasma (UWAP). The OH· radical converted non-fluorescent terephthalic acid to fluorescent hydroxyterephthalic acid (HTA). As determined from HTA formation, when a 500 ppm H 2O 2 dose in tap water was combined with O 3 and sonication, nearly twice as much OH· (0.72 ppm) accumulated than with H 2O 2 alone. When UWAP accompanied H 2O 2, O 3, and sonication, these together generated 15–35% more OH· than when UWAP was excluded. When ozone was introduced into this AO system, the AO system decomposed almost all the O 3. This research has been conducted as a part of a study that has appraised this advanced oxidation system (Sonoperoxone) in green sand foundries, where it has diminished volatile organic compound (VOC) and hazardous air pollutant (HAP) emissions by 20–75%; and clay and coal consumption by 20–35%. 相似文献
6.
This laboratory study was designed to investigate the degradation of 4-chloronitrobenzene ([CNB] = 2.4 × 10 ?6 mol L ?1; pH = 7.5) by H 2O 2/UV and by O 3/UV oxidation processes which involve the generation of very reactive and oxidizing hydroxyl free radicals. The effects of the oxidant doses (H 2O 2 or aqueous O 3), liquid flow rate (or the contact time), and bicarbonate ions acting as OH· radical scavengers on the CNB removal rates were studied. For a constant oxidant dose, the results show that the O 3/UV system appears to be more efficient than the H 2O 2/UV system to remove CNB because of the greatest rate of OH· generation by ozone photodecomposition compared to H 2O 2 photolysis. However, for a given amount of oxidant decomposed, the H 2O 2/UV oxidant system was found to be more efficient than O 3/UV. Moreover, high levels of bicarbonate ions in solution (4 × 10 ?3 mol L ?1) significantly decrease the efficiency of CNB removal by H 2O 2/UV and by O 3/UV oxidation processes. 相似文献
7.
A series of phosphotungstic quaternary ammonium salts, Q 3 (PW 12O 40) and Q 3(PW 4O 16) [Q = (C 5H 5)N +(C 16H 33), (C 16H 33)N +(CH 3) 3, (C 4H 9) 4N +, and (CH 3) 4N +], were used as the catalysts in oxidation of cyclopentene. The catalysts [(C 5H 5)N(C 16H 33)] 3(PW 4O 16) and [(C 16H 33)N(CH 3) 3] 3(PW 4O 16) showed high catalytic activity in the selective oxidation of cyclopentene while using H 2O 2 (50%) as an oxidant and 2-propanol as a solvent. The oxidation products mainly consisted of glutaraldehyde, cis-1,2-cyclopentanediol and trans-1,2-cyclopentanediol. The above-mentioned two catalysts were dissolved completely in the reaction medium during the catalysis process and precipitated themselves from the reaction system after reaction, showing the characteristics of reaction-controlled phase-transfer catalysis. The types of quaternary ammonium cations and the phosphotungstic anions in phosphotungstic quaternary ammonium salts affected catalytic activity. 相似文献
8.
Self-assembled monolayer (SAM) films of iron (SAM- 1), cobalt (SAM- 2) and manganese (SAM- 3) phthalocyanine complexes, tetra-substituted with diethylaminoethanethio at the non-peripheral positions, were formed on gold electrode in dimethylformamide (DMF). Electrochemical, impedimentary and surface properties of the SAM films were investigated. Cyclic voltammetry was used to investigate the electrochemical properties of the films. Ability of the films to inhibit common faradaic processes on bare gold surface (gold oxidation, solution redox chemistry of [Fe(H 2O) 6] 3+/[Fe(H 2O) 6] 2+ and underpotential deposition (UDP) of copper) was investigated. Electrochemical impedance spectroscopy (EIS), using [Fe(CN) 6] 3−/4− redox process as a probe, offered insights into the electrical properties of the films/electrode interfaces. Surface properties of the films were probed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The films were employed for the electrocatalytic oxidation of the pesticide, carbofuran. Electrocatalysis was evidenced from enhanced current signal and less positive oxidation potential of the pesticide on each film, relative to that observed on the bare gold electrode. Mechanism of electrocatalytic oxidation of the pesticide was studied using rotating disc electrode voltammetry. 相似文献
9.
Oxidation with O 3/H 2O 2 and Fe 2+/H 2O 2 are optional for the degradation of herbicides and pesticides in water. The choice of which process will be applied depends upon the degree of degradation of organic micropollutants and the process conditions related to the formation of oxidation by-products, and also on the total costs and the safety and reliability of the process. Under real conditions, atrazine and some phenylureaherbicides were oxidized with O 3/H 2O 2. Comparable experiments under conditions of different pH, iron and DOC content were performed with Fe 2+/H 2O 2, in order to gain information on the influence of these parameters. The oxidation results of both processes as well as the formation of bromate as one of the oxidation by-products are described. It was found that 80% of atrazine and >99% of some phenylureaherbicides could be degraded with O 3/H 2O 2 at pH 7.8 (H 2O 2/O 3 ratio 3.7 g/g). Under these conditions, bromate was formed up to 5 μg/1. Comparable results were obtained with Fe 2+/H 2O 2 at a pH value of 5.5, whereas the formation of bromate was kept below 0.2 μg/L. 相似文献
10.
Model dyeing and laundering wastewaters produced during two basic technological operations of the textile industry were subjected to treatment by advanced oxidation processes (AOPs). The following agents were used: ozone (O 3), hydrogen peroxide (H 2O 2) and UV radiation. They were applied separately and in all possible combinations: O 3 + UV, O 3 + H 2O 2, UV + H 2O 2, as well as all three at the same time: O 3 + UV + H 2O 2. Effluents before and after the treatment were analyzed according to requirements of the Polish Standards that included pH, color threshold, COD and concentration of anionic and non-ionic surfactants. Ozonation was carried out in a lab-scale bubble column reactor with a centrally located UV burner. The most effective version of AOPs proved to be the simultaneous use of all three agents. In the case of such treatment of dyeing wastewaters nearly complete discoloration and full decomposition of surface-active substances were obtained at 80% reduction of COD. A similar tendency was observed in the case of laundering wastewater, though in that case the results were slightly worse, which may be explained by much higher initial concentrations of the pollutants. Good treatment effects have also been obtained in combined treatment by simultaneous use of hydrogen peroxide and ozone. 相似文献
11.
Converting elemental mercury into divalent compound is one of the most important steps for mercury abatement from coal fired flue gas. The oxidation of elemental mercury was investigated in this paper using dielectric barrier discharge (DBD) non-thermal plasma (NTP) technology at room temperature. Effects of different flue gas components like oxygen, moisture, HCl, NO and SO 2 were investigated. Results indicate that active radicals including O, O 3 and OH all contribute to the oxidation of elemental mercury. Under the conditions of 5% O 2 in the simulated flue gas, about 90.2% of Hg 0 was observed to be oxidized at 3.68 kV discharge voltage. The increase of discharge voltage, O 2 level and H 2O content can all improve the oxidation rate, individually. With O 2 and H 2O both existed, there is an optimal moisture level for the mercury oxidation during the NTP treatment. In this test, the observed optimal moisture level was around 0.74% by volume. Hydrogen chloride can promote the oxidation of mercury due to chlorine atoms produced in the plasma process. Both NO and SO 2 have inhibitory effects on mercury oxidation, which can be attributed to their competitive consumption of O 3 and O. 相似文献
12.
Effluent from the Pa?aköy Wastewater Treatment Plant was oxidized by using O 3 and O 3/H 2O 2. DOC, COD, UV 254, total coliform, dissolved ozone and some endocrine disrupting compounds were monitored during oxidation. Results showed that O 3 provided superior disinfection, however, lower reductions in DOC, COD and endocrine disrupting compounds were exhibited compared to O 3/H 2O 2. The highest removal efficiency of DOC, COD and endocrine disrupting compounds were achieved at 0.5 molar ratio of O 3/H 2O 2. The benefit of H 2O 2 addition for advanced oxidation reduced significantly when the mole ratio was increased to 2. Therefore, the mole ratio of H 2O 2 to O 3 is a critical parameter for the design of wastewater oxidation by O 3/H 2O 2. 相似文献
13.
In the present work, a comparative study of a mixture of three pesticides (chlortoluron, carbofuran and bentazon) has been investigated by advanced oxidation processes such as photo-Fenton and electro-Fenton. These processes are based on the in situ production of hydroxyl radical, a highly strong oxidant, which allows the degradation of organic pollutants until their mineralization into CO 2 and H 2O. For the photo-Fenton process, the effect of key parameters such as initial catalyst (Fe 3+) concentration and hydrogen peroxide (H 2O 2) dosage were studied. Under optimal operating conditions, the evolution of total organic carbon (TOC) has been investigated for the two processes. Obtained results showed that more than 90% of TOC removal was obtained after only 2 h of photo-Fenton treatment whereas the electro-Fenton process needed 8 h of treatment. Nevertheless, the comparison of cost treatment shows that the photo-Fenton process is more expensive than electro-Fenton. The evolution of pesticide's concentration during treatment was determined by high performance liquid chromatography (HPLC). Inorganic ions released such as chloride, nitrate, sulphate and ammonium ions are identified and their kinetic evolution was measured by ion chromatographic analyses. 相似文献
14.
Pesticides are generally utilized one after another for crop conservation, and this pesticide utilization oftentimes resulting in combined pollution of their residues in the environment. An experimental study was performed on the degradation of dinoseb and imidacloprid. In this research, GO/CuFe 2O 4–CdS nanocomposite was synthesized as a high-efficiency photocatalyst for the process of pesticides pollutants from water. Field Emission Scanning Electron Microscopy with Energy Dispersive X-ray (FESEM-EDX), X-Ray Diffraction (XRD), Vibrating-sample Magnetometer (VSM), and Fourier Transform Infrared spectroscopy (FTIR) analyses are applied to study the properties of this nanocomposite. Dinoseb and imidacloprid as pesticide materials have been utilized as water contaminants and their degradation performance using the synthesized photocatalyst is considered. The effect of initial pH, photocatalyst amount, initial pesticide concentration and degradation time are investigated in this research. The optimum values for both pesticides were as follows: pollutant concentration was 10 ppm, the nanocatalyst amount was 100 mg, irradiation time was 100 min and the pH of pesticide solution equaled to 8. The results showed that the GO/CuFe 2O 4–CdS nanocomposite is the efficient nanocatalyst for degradation of these pesticides. 相似文献
16.
BACKGROUND: Particles are often too small to be separated from a reaction system and recycled, especially in waste‐water treatment via a catalytic ozonation process. Therefore, the objective of this study was to prepare a magnetic catalyst (SiO 2/Fe 3O 4) that can be recycled by using an external magnetic field. The characteristics of the magnetic catalyst and kinetics of decomposition of Reactive Black 5 (RB5) using a magnetic catalyst/H 2O 2/O 3 have been investigated. Magnetic catalysts (SiO 2/Fe 3O 4) were characterized by X‐ray diffraction (XRD), vibrating sample magnetometry (VSM) and Fourier transform infrared (FTIR) spectroscopy. RESULTS: In the case of the decomposition of RB5 by the SiO 2/Fe 3O 4/H 2O 2/O 3 process, the contribution of the destruction by the indirect oxidation of OH· caused by the chain reaction of H 2O, OH ?, and H 2O 2 was found to be larger than that of the direct attack of O 3. The kinetic behaviour of the reacting species during the decomposition of RB5 by catalytic ozonation could be well modelled under various experimental conditions. CONCLUSIONS: The paramagnetic behaviour of the prepared SiO 2/Fe 3O 4 led to the formation of the magnetic catalyst SiO 2/Fe 3O 4, which could be separated more easily by the application of a magnetic field. More than 90% of the magnetic catalyst was recovered and easily redispersed in a solution for reuse by mixing with a flat‐bladed turbine. Copyright © 2010 Society of Chemical Industry 相似文献
17.
The influence of hydrogen peroxide on the adsorption and oxidation of carbon monoxide, methanol and ethanol adlayers on porous Pt electrodes were studied in 2 M sulphuric acid solution by means of cyclic voltammetry and differential electrochemical mass spectrometry (DEMS). The oxidation of adsorbed species is observed at electrode potentials far less negative than those required for electrochemical adsorbate oxidation. The oxidation by H 2O 2 is dependent on its concentration in solution, as well as on the adsorbates and their coverages. In all cases the isolated adlayers are oxidised by dissolved H 2O 2. However, the presence of H 2O 2 during adsorption partially inhibits adlayer formation from CH 3OH and C 2H 5OH, but avoids almost completely the adsorption of carbon monoxide. The removal of the residues from the surface by dissolved hydrogen peroxide probably occurs through O ad species formed during the heterogeneous decomposition reaction of H 2O 2 on Pt. 相似文献
18.
The efficiency of ozonation and advanced oxidation processes such as ozone/UV, ozone/H 2O 2 and H 2O 2/UV was assessed for chlorinated hydrocarbons using a closed batch-type system. 1,1-Dichloropropene (DCPE), trichloroethylene (TCE), 1-chloropentane (CPA), and 1,2-dichloroethane (DCA) were used as model compounds. The direct reaction between substrates and ozone predominated at lower pH, which resulted in the efficient oxidation of the olefin, DCPE. At higher pH, ozonation resulted in more efficient oxidation of the chlorinated alkanes, with a corresponding decrease in the efficiency of DCPE oxidation. Consistent results were observed for ozone/H2O2 and ozone/UV treatment. Due to slow UV-induced decomposition of H2O2, the process using H2O2/UV (254 nm) resulted in very slow oxidation of all four compounds. The total ozone requirement to achieve a given degree of elimination (to 37% of the original concentration), δ0.37, was used to assess the combined effects of the direct and indirect reactions for different types of waters. 相似文献
19.
利用(3-氨丙基)三乙氧基硅烷(apts)将钌金属杂多酸[X 2W 20O 70(RuY) 2] 10-(其中,X为锑或铋,Y为苯或对异丙基苯甲烷)固定在介孔的SBA-15上可得到一系列性能优良的SBA-15锚定的钌杂多酸催化剂。采用XRD、N 2吸附-脱附实验和FT-IR红外光谱对此类催化剂进行表征,并检测其对正十六烷氧化的催化性能。结果表明,以空气为氧化剂,在无任何溶剂的条件下,该锚定的钌杂多酸催化剂遵循传统的自由基自氧化机理,将正十六烷烃氧化成各种醇类和酮类,显示出优良的催化性能。因此,这类多相催化剂对环境友好的烷烃氧化反应具有较高的应用价值。 相似文献
20.
Ceramic coatings were fabricated on ZK60 magnesium alloy substrate by microarc oxidation (MAO) in Na 2SiO 3–KOH base electrolyte with four kinds of additives (i.e. KF, NH 4HF 2, C 3H 8O 3 and H 2O 2). The effects of these additives on microstructure and property of coatings were investigated. The surface morphology, phase composition and corrosion resistance of the ceramic coatings were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and simulation body fluid (SBF) immersion test respectively. It is found that different additives can change the spark discharge phenomenon during microarc oxidation. It is proved that both potassium fluoride (KF) and ammonium bifluoride (NH 4HF 2) promote discharge and accelerate reaction while the introduce of glycerol (C 3H 8O 3) leads to the refining of sparks and reduction of thermal effects. Results also demonstrate that the introduce of hydrogen peroxide (H 2O 2) contributes to the increase of coating surface roughness and enlargement of surface micropore size. XRD results indicate that the ceramic coatings are mainly composed of Mg 2SiO 4, MgSiO 3 and SiO 2. The introduce of H 2O 2 hinders the reaction between SiO 2 and MgO and creates favorable conditions for the formation of the MgO phase. The ceramic coatings formed in base electrolyte containing 7 g/L NH 4HF 2 and 5 mL/L C 3H 8O 3 exhibit the highest corrosion resistance. 相似文献
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