共查询到20条相似文献,搜索用时 15 毫秒
1.
ABSTRACTAntibiotics are non-biodegradable and can remain for a long time at aquatic environments and they have a big potential bio-accumulation in the environment. The antibiotics are broadly metabolized by humans, animals and plants and they or their metabolites, after metabolization, are entered into the aquatic environment. This study aimed to optimize the operational parameters by Taguchi design and to carry out the kinetic studies for removal of cephalexin antibiotic from aqueous solutions by US/H2O2/NiO hybrid process. This experimental study was performed on a laboratory scale in a 500 mL pyrex-made reactor. The main operational parameters to influence the US/H2O2/NiO process were identified as the initial concentration of CEX (20–80 mg/L), hydrogen peroxide (H2O2) (10–40 mL/L), NiO nanoparticle (2.5–10 mg/L) and reaction time (15–90 min) and therefore, the influence of these factors were studied. Under optimum conditions (pH = 3, reaction time = 90 min, CEX = 40 mg/L, NiO = 7.5 mg/L and H2O2 = 30 mL/L) and using the US/H2O2/NiO process, the removal efficiencies of CEX, COD and TOC were 93.86%, 72.46% and 54.55%, respectively. The percentage contribution of each factor was also determined. Results introduced the solution pH as the most powerful factor, and its percentage contribution value was up to 94% in the studied process. It was also identified that the removal of CEX antibiotic using the hybrid process obeys the pseudo-first-order kinetics. 相似文献
2.
Francisco J. Real F. Javier Benitez Juan L. Acero Manuel Gonzalez 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2007,82(6):566-574
Diazinon is a widely used organophosphorus insecticide that is an important pollutant in aquatic environments. The chemical removal of diazinon has been studied using UV radiation, ozone, Fenton's reagent, UV radiation plus hydrogen peroxide, ozone plus hydrogen peroxide and photo‐Fenton as oxidation processes. In the photodegradation process the observed quantum yields had values ranging between 2.42 × 10?2 and 6.36 × 10?2 mol E?1. Similarly, the ozonation reaction gave values for the rate constant ranging between 0.100 and 0.193 min?1. In the combined systems UV/H2O2 and O3/H2O2 the partial contributions to the global oxidation reaction of the direct and radical pathways were deduced. In the Fenton's reagent and photo‐Fenton systems, the mechanism of reaction has been partially discussed, and the predominant role of the radical pathway pointed out. Additionally, the rate constant for the reaction between diazinon and the hydroxyl radicals was determined, with the value 8.4 × 109 L mol?1 s?1 obtained. A comparison of the different oxidation systems tested under the same operating conditions revealed that UV radiation alone had a moderate oxidation efficiency, which is enhanced in the case of ozone, while the most efficient oxidant is the photo‐Fenton system. Copyright © 2007 Society of Chemical Industry 相似文献
3.
《分离科学与技术》2012,47(16):2453-2464
The objectives of this study were to investigate the effects of ozone and the O3/H2O2 process on FeCl3 coagulation efficiency for the removal of the high content of natural organic matter (NOM) and arsenic (As) from groundwater (DOC = 9.27 ± 0.92 mg/L; 51.7 ± 16.4 µg As/L). Arsenic and NOM removal mechanisms during coagulation/flocculation are well investigated. However, data concerning arsenic removal in the presence of NOM, which is the subject of this article, are still insufficient. Laboratory and pilot plant test results have shown that the competition of NOM and As for adsorption sites on the coagulant surface have great influence on coagulation/flocculation efficiency for their removal. With both oxidation pre-treatments, arsenic content after the coagulation process was less than 2.0 µg/L in treated water. Application of ozone has a lower influence on coagulation efficacy in terms of DOC reduction, compared to the O3/H2O2 process with the same ozone dose. 相似文献
4.
Hsing Yuan Yen 《臭氧:科学与工程》2016,38(2):163-171
This study evaluated the feasibility of treating color filter effluent by H2O2/UV pre-oxidation and membrane postseparation for in-house reuse. The effluent qualities were TOC of 5.8–34 mg/L, color of 46–138 ADMI, and conductivity of 1020–3500 μS/cm. Although the RO separation could directly remove TOC, color, and conductivity effectively, the serious fouling problem still existed. Through H2O2/UV pre-oxidation (UV = 13 W, H2O2 = 200 mg/L), organic and biofouling were inhibited to increase the normalized flux decline from 5% to 77%. That is, H2O2/UV pre-oxidation could mitigate the permeate flux decline as well as to improve the water quality for water reuse. 相似文献
5.
Ozonation and four types of advanced oxidation processes, including O3/H2O2, O3/UV, O3/H2O2/UV, and UV/H2O2, were evaluated for the treatment of contaminated groundwater at a Superfund site in Simpsonville, South Carolina using bench-scale, batch ozone and UV apparatuses. Although the contaminants of concern were 1,4-dioxane, 1,1-dichloroethene, and trichloroethene, several other chlorinated organics as well as tetrahydrofuran were found in the groundwater samples. The O3/H2O2 treatment with O3 and H2O2 doses of 6 and 1.5 mg/L, respectively, and the UV/H2O2 treatment with UV and H2O2 doses of 1,000 mJ/cm and 20 mg/L, respectively, were sufficient to degrade 200 µg/L of 1,4-dioxane, 110 µg/L of 1,1-dichloroethene, and 10 µg/L of trichloroethene below their performance standards of 10, 7, and 4 µg/L, respectively. Due to a high bromide concentration (0.35 mg/L) in the groundwater sample, bromate formation was found to be significant in ozone-based treatment, including O3/H2O2. 相似文献
6.
《国际聚合物材料杂志》2012,61(11):533-547
Development of new economically feasible eco-friendly products from agricultural wastes for the removal of pollutants from water is the objective of many researchers. In this study, attempts have been made to use sunflower stems for the removal of Mn(II) and phenol from water. An ion-exchange resin was fabricated through the hydrolysis of graft copolymer of pretreated sunflower stem with acrylamide that was made by Fe2+/H2O2 initiator. Factors affecting the grafting reaction, such as grafting time and temperature as well as initiator and monomer concentration, were studied. The hydrolysis under basic/acidic conditions was also studied. In addition to grafting, the charring of sunflower stem was studied at 400°C. Our results showed that the optimum condition for grafting was sunflower stem: monomer = 1:3, at 30°C, weight of Fe2+/2 g bleached sunflower stem = 0.5 g, and grafting time 2 h. The maximum removal capacity for Mn(II) was found with the alkali and acidic hydrolyzed grafted sunflower stem, while the charred sunflower stem had the highest efficiency for removal of phenol from water. 相似文献
7.
The characteristics and influencing factors for dinitrotoluene degradation by nano-Fe3O4-H2O2 were studied, and the nano-scale Fe3O4 catalyst was prepared by the coprecipitation method, with dinitrotoluene wastewater as the degradation object. The results showed that the catalytic reaction system within the pH value range of 1 to 9 could effectively degrade dinitrotoluene, and the optimal pH value was 3; with the increase of catalyst dosage, the degradation efficiency and the catalytic reaction rate of dinitrotoluene grew as well. The optimal catalyst dosage was 1.0 g/L when the H2O2 dosage was within the range of 0 to 0.8 mL/L; the degradation efficiency and reaction rate grew with the increase of H2O2 dosage. With further increase of H2O2 dosage, degradation efficiency and reaction rate decreased; under the best conditions with the H2O2 dosage of 0.8 mL/L, the catalyst concentration of 1 g/L and the pH value of 3 at room temperature (25 °C), the degradation rate of the 100-mg/L dinitrotoluene in 120 min reached 97.6%. Through the use of the probe compounds n-butyl alcohol and benzoquinone, it was proved that the oxidation activity species in the nano-Fe3O4-H2O2 catalytic system were mainly hydroxyl radical (?OH) and superoxide radicals (HO2 ?), based on which, the reaction mechanism was hypothesized. 相似文献
8.
《分离科学与技术》2012,47(17):2727-2740
ABSTRACTIn this study, response surface methodology was applied for food wastewater by electrocoagulation (EC) and electro-Fenton (EF) processes. The optimum conditions for the chemical oxygen demand (COD) removal were found to be 21.36 min, pH 10 and 86 mA/cm2 in EC, whereas 27.11 min, pH 2.38, 86 mA/cm2 and H2O2/COD:2 in EF process. COD removal efficiencies were determined to be 29.4% for EC and 59.1% for EF processes and higher than 99% total suspended solids removal efficiencies were achieved. It can be concluded that high COD removal was obtained (4998 mg/L COD removal by EC and 10,047 mg/L COD removal by EF). 相似文献
9.
Nader Rahemi Mohammad Haghighi Ali Akbar Babaluo Mahdi Fallah Jafari Somaiyeh Allahyari 《Korean Journal of Chemical Engineering》2014,31(9):1553-1563
Argon glow discharge plasma was applied for treatment of impregnated Ni-Cu/Al2O3-ZrO2 nanocatalyst. The catalytic performance toward CO2 reforming of methane and the physicochemical properties were investigated by means of GC, BET, XRD, FESEM, TEM, EDX, TG-DTG, XPS and FTIR techniques. The plasma-treated nanocatalyst contains smaller crystal size and high dispersion of NiO. Plasma treatment decreased particle size and plasma high energy species flattened particles on support, increasing the interaction between support and active metals which leads to high catalytic activity. Low temperature activity and H2/CO ratio closer to 1 was observed for plasma-treated nanocatalyst compared to non-treated sample. Moreover, higher product yield and H2/CO ratio was found in CH4/CO2=1 rather than CH4/CO2=1.5. Time on stream test during 1,440 min at 850 °C showed plasma-treated Ni-Cu/Al2O3-ZrO2 nanocatalyst did not experience any deactivation in terms of CH4 and CO2 conversion and H2/CO ratio. 相似文献
10.
The ZnO/ZnMn2O4 nanocomposite (ZnMn) was used as adsorbent for the removal of cationic dye Basic Yellow 28 (BY28) from aqueous solutions. The adsorbent was characterized by X-ray diffraction, scanning electron microscope, TEM, Fourier transform infrared ray, BET, particle size distribution and zeta potential measurements. The adsorption parameters, such as temperature, pH and initial dye concentration, were studied. Kinetic adsorption data were analyzed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The Langmuir and Freundlich isotherm models were applied to fit the equilibrium data. The maximum adsorption capacity of BY28 was 48.8 mg g?1. Various thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, were calculated. 相似文献
11.
Vinita R. Dubey 《Chemical Engineering Communications》2016,203(9):1234-1241
In a bio-refinery focused on fast pyrolysis, hydrogen (H2) producible from reforming of the aqueous fraction of bio-oil with steam can be utilized for upgrading pyrolytic lignin into fuels by hydrotreatment. In this work, propylene glycol (PG) was chosen as a typical compound symbolizing higher polyols in the bio-oil aqueous fraction. Catalytic processing of PG into H2 at low temperature (T = 500°C) was investigated using several commercial catalysts such as Ni/Al2O3, Ru/Al2O3, Ru/C, Pt/C, and Pd/C in a laboratory-scale fixed-bed reactor. The efficiencies of the catalysts were presented as selectivity to CO, CO2, CH4 and H2, and PG conversion into gaseous phase. Wide ranges of temperature (300–500°C), W/FO (18.6–92.9 g h/mol), and S/C ratio (5.6–12.7 mol/mol) were examined using Ni/Al2O3. At T = 500°C, H2 selectivity (73.7%) and PG conversion (66.2%) were maximized using ratios of catalyst mass to molar flow rate of PG (W/FO) = 18.6 g h/mol and steam to carbon (S/C) = 12.7 (10 wt% PG solution). It was found that Ni/Al2O3 demonstrates stable operation for at least 6 h of time-on-stream. Finally, a plausible reaction pathway for PG reforming was proposed. 相似文献
12.
The Au/Ce1?x Zr x O2 (x = 0, 0.25, 1) catalysts were synthesized, characterized by BET, XRD, TPR-H2, HRTEM, AAS and tested in CO oxidation. The effect of moisture in the reactant gas on CO conversion has been studied in a wide range of concentrations (~0.7–6000 ppm). Moisture generates a positive effect on catalytic activity and wet conditions gave higher CO conversions. The optimum concentration of moisture for CO oxidation over Au/CeO2 and Au/Ce0.75Zr0.25O2 is 200–1000 ppm, while further increase in the moisture content suppresses CO conversion. The activity of the studied Au catalysts depends on the amount of moisture adsorbed on the catalyst rather than on its content in the feed stream, which suggests that the reaction involves water-derived species on the catalysts surface. The effect of the catalysts pretreatment in air, dry He, H2 stream as well as H2 + H2O gas mixture on their catalytic performance in CO oxidation has been also investigated. The model of the active sites for CO oxidation over the studied catalysts was proposed. 相似文献
13.
In this paper, the removal of phenol from simulated wastewater was studied using gas–liquid fluidized bed with the Fenton reagent. The factors that affect the removal rate of phenol were investigated, including the initial concentrations of hydrogen peroxide [H2O2] and [Fe2+], the molar ratio of [Fe2+]/[H2O2], pH value, temperatures, reaction time, and the ventilation volume. It was found that the optimal operating conditions existed as: [H2O2] = 12 mmol/L, [H2O2]/[Fe2+] = 4:1, pH = 4, T = 60 °C, reaction time of 30 min, and a ventilation volume of 0.12 m3/h. Under these conditions, the phenol removal rate of about 96% was obtained. 相似文献
14.
Rui-tang Guo Wei-guo Pan Xiao-bo Zhang Jian-xing Ren Qiang Jin Hong-jian Xu Jiang Wu 《Fuel》2011,90(11):3295-3298
Removal of NO was studied in a lab-scale bubbling reactor. Effects of operation parameters such as pH value, H2O2 concentration, NO inlet concentration and reaction temperature on NO removal efficiency were investigated. The operation parameters included 250–1000 ppm NO, 0.5–1.5 mol/L H2O2, FeSO4 0.05 mol/L, 2–6 pH, 25–70 °C. As can be seen from the experimental results, pH value had a great impact on NO removal efficiency. The experimental results indicated that the gas–liquid reaction between NO and Fenton reagent solution was liquid-film controlled as NO inlet concentration exceeded 600 ppm. And NO removal efficiency decreased with increasing reaction temperature. 相似文献
15.
Kohtaroh Nakamoto 《分离科学与技术》2019,54(4):523-534
Cerium oxide composited activated alumina was prepared and used as arsenate and arsenite adsorbents by oxidation of cerium chloride in H2O2 solution. The preparation conditions affected arsenic adsorption capabilities in the Al2O3–CeO2. Efficient adsorption of arsenic was achieved when CeO2 was deposited on 6.0 g of powdered activated alumina at 0.01 M Ce3+ concentration and H2O2/Ce = 0.5. The arsenic adsorption was particularly enhanced in the presence of the nano-size CeO2 on the Al2O3 support, obeying the Langmuir adsorption isotherm model with maximum adsorption capacities of 13.6 and 10.5 mg/g, respectively, for arsenate and arsenite. 相似文献
16.
This work discusses the effects of Fenton oxidation pre-treatment on the lime purification of raw sugar beet juice using iron powder and hydrogen peroxide. During Fenton oxidation, particular attention was paid to the effect of reaction time and dosage of Fenton′s reagent to improve purification indexes of the raw juice throughout the clarification process. The total concentration of lime used for the purification was varied from 4.0 to 16.0 g of CaO/100 mL of juice. The results showed that higher color and total phenolic removal were achieved with an increase in H2O2 dosage and reaction time. At an initial pH of less than 6.2 and H2O2 concentration of 7000.0 ppm, color removal reached 85% and approximately 81% of total phenolic removal was achieved at a reaction time of 30 min (Treatment 5). It suggests that the quantity of CaO required for the efficient juice purification may be decreased from 16.0 g/100 mL for the control juice to approximately 12.0 g/100 mL for the juice obtained from Treatment 5. Fenton oxidation process improved the quality indexes of the purified juice, and can be combined with a conventional clarification process to achieve juice with high purity and low color. 相似文献
17.
Rui C. Martins Renato F. Dantas Carme Sans Santiago Esplugas Rosa M. Quinta-Ferreira 《臭氧:科学与工程》2015,37(6):509-517
This work aims to analyze the contribution of H2O2 on ozonation of Sulfamethoxazole (SMX). A single ozonation was able to totally remove SMX. TOC and COD depletion rates after a transferred ozone dose of 60 mg/L was related to the formation and decomposition of H2O2. An increase on O3 gas inlet concentration from 10 g/m3 to 20 g/m3 improved COD abatement from 11% to 36%. When the presence of H2O2 at the beginning of ozonation was tested, it was verified that COD and TOC degradation were enhanced, attaining maximum values of 76% and 32%, respectively, when compared with 35% and 15% reached in a single ozonation. 相似文献
18.
《分离科学与技术》2012,47(1):68-73
To improve the performance of wet oxidation for the regeneration of GAC, a microwave assisted wet peroxide oxidation process has been applied for the regeneration of 4-chlorophenol exhausted GAC. The effects of various factors including reaction temperature, H2O2 dosage, reaction time, and addition of catalyst have been studied. The regeneration improves with the increase in reaction temperature, H2O2 dosage, and reaction time. The addition of Cu2+ further promotes the regeneration process. Under the conditions of temperature 150°C, H2O2 dosage 15 mmol, reaction time 20 min, Cu2+ concentration 20 mg/L, the regenerated GAC recovers 93.5% of its adsorption capacity. A nearly complete degradation of 4-chlorophenol in the aqueous phase is observed based on UV-vis and high-performance liquid chromatography spectra studies. 相似文献
19.
Taous Aissani Idris Yahiaoui Farouk Boudrahem Sabrina Ait Chikh Farida Aissani-Benissad Abdeltif Amrane 《分离科学与技术》2018,53(9):1423-1433
The major factors affecting the removal efficiency of sulfamethazine (SMT) by photocatalysis process in the presence of TiO2 P25 or ZnO, namely the pH, the amount of catalyst and the initial SMT concentration were examined. The obtained results showed the absence of adsorption of SMT on the catalysts and the absence of degradation of SMT by direct photolysis under UV light in the absence of catalyst. The variation of the pH solution in the range 4–9 did not cause any significant degradation of SMT. The optimal amounts of each catalyst were, respectively, 0.5 and 0.25 g/L for TiO2 P25 and ZnO. Increasing the initial SMT concentration impacted negatively the removal efficiency, which decreased from 31% to 13% and from 100% to 27% in the presence of TiO2 P25 and ZnO in the presence of 10 mg/L and 50 of SMT after 30-min reaction time, respectively. The obtained results showed better efficiency of ZnO than TiO2 P25 regarding both removal efficiency and chemical oxygen demand (COD) abatement. However, removal efficiency and COD abatement were not complete, even after 7 h of photocatalysis, about 92% and 41%, respectively. The biodegradability was examined after photocatalysis performed in the following conditions: [SMT]0 = 50 mg/L, pH = 6, T = 25°C, ω = 360 rpm and 0.5 g/L of TiO2 P25 or 0.25 g/L of ZnO. In these conditions, the removal efficiencies were, respectively, 26% and 41% in the presence of TiO2 P25 and 55 and 92% in the presence of ZnO after 4 and 7 h of pretreatment times, respectively. The BOD5/COD ratio increased substantially and, respectively, from 0 to 0.25 and from 0 to 0.16 in the presence of TiO2 P25 and ZnO after 7 h of irradiation. Even if the limit of biodegradability (0.4) was not achieved, a subsequent biological treatment was considered in the presence of TiO2 P25, leading to 58% COD abatement after a 28-day culture. 相似文献
20.
《分离科学与技术》2012,47(18):3115-3127
ABSTRACTIn this paper, the modeling and the optimization of the removal efficiency of ketoprofen (KTP) by the electrocoagulation process were studied. The central composite design experiments (CCD) method was used to study the main effects and the interaction effects between operational parameters and to optimize the value of each parameter. According to the regression equation obtained, the current density appears to be one of the most important parameters (b2 = +22.11) controlling the removal efficiency of KTP. The positive sign of b2 coefficient suggests that the increase of current density increases the yield of removal. The second signi?cant parameter with a negative effect was the initial KTP concentration (b3 = ?16.27). This result suggests that the removal efficiency was inversely proportional to the initial concentration. In addition, according to the model, the most influencing interactions were pH-current density, pH-initial concentration, and current density-initial concentration. The model obtained by CCD led to the following optimal conditions for KTP removal e?ciency (96.70%): pH = 7, i = 24.04 mA cm?2, and C0 = 5 mg L?1. 相似文献