共查询到12条相似文献,搜索用时 15 毫秒
1.
Salima Chergui Ahmed Réda Yeddou Abdelmalek Chergui Farid Halet Hamza Amaouche Boubekeur Nadjemi 《毒物与环境化学》2015,97(10):1289-1295
This work is dedicated to the removal of free cyanide from aqueous solution by oxidation with hydrogen peroxide H2O2 catalyzed by neutral activated alumina. Effects of initial molar ratio [H2O2]0/[CN?]0, catalyst amount, pH, and temperature on cyanide removal have been examined. The presence of activated alumina has increased the reaction rate showing thus, a catalytic activity. The rate of removal of cyanides increases with rising initial molar ratio [H2O2]0/[CN?]0 but decreases at pH 10 to 12. Increasing the alumina amount from 1.0 to 30 g/L has a beneficial effect, and increasing the temperature from 20 °C to 35 °C improves cyanide removal. The kinetics of cyanide removal has been found to be of pseudo-first-order with respect to cyanide and the rate constants have been determined. 相似文献
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采用C/PTFE气体扩散电极在无隔膜体系中进行H2O2发生工艺研究,探讨了石墨和Vulcan XC-72碳黑两种碳材料以及电解电压、p H值对该反应过程的影响.结果表明,在较低的空气流量(1.41 cm3·min-1·cm-2)下,以Vulcan XC-72碳黑为表面的气体扩散电极相比石墨电极有较高的H2O2产率和电流效率,碱性条件比酸性条件下H2O2产率和电流效率更好;在2.6 V恒定电压下,2 h后,H2O2浓度达到了250 mg·L-1,电流效率从69.8%降到44.7%,单位产量能耗从5.87 k Wh·kg-1升高到9.16 k Wh·kg-1. 相似文献
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Microwave and Fenton's reagent oxidation of wastewater 总被引:16,自引:0,他引:16
We compared two H2O2 oxidation methods for the treatment of industrial wastewater: oxidation using Fenton's reagent [H2O2/Fe(II)] and microwave irradiation. Both methods were applied to the treatment of synthetic phenol solutions (100 mg L−1) and of an industrial effluent containing a mixture of ionic and non-ionic surfactants at high load (20 g L−1 of COD). The effects of initial pH, initial H2O2 concentration, Fenton catalyst amount and irradiation time were assessed. According to the oxidation of phenol, it has been
found that the oxidation by Fenton's reagent is dependent on the pH, contrary to the microwave system, which is not influenced
by this parameter. For both systems, a limiting amount of oxidant has been found; above this point the oxidation of phenol
is not improved by a further addition of peroxide. The oxidation of the industrial surfactant effluent has only been successful
with the Fenton's reagent. In this case, large amounts of ferrous ions are necessary for the precipitation of the ionic surfactants
of the effluent, followed by the oxidation of the non-ionic constituents of the solution.
Electronic Publication 相似文献
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The effects of nitrate on fermentative hydrogen production and soluble metabolites from mixed cultures were investigated by varying nitrate concentrations from 0 to 10 g N/L at 35°C with an initial pH of 7.0. The results showed that the substrate degradation rate, hydrogen production potential, hydrogen yield, and average hydrogen production rate initially increased with increasing nitrate concentrations from 0 to 0.1 g N/L, while they decreased with increasing nitrate concentrations from 0.1 to 10 g N/L. The maximum hydrogen production potential of 305.0 mL, maximum hydrogen yield of 313.1 mL/g glucose, and maximum average hydrogen production rate of 13.3 mL/h were obtained at a nitrate concentration of 0.1 g N/L. The soluble metabolites produced by the mixed cultures contained only ethanol and acetic acid (HAc) without propionic acid (HPr) and butyric acid (HBu). This study used the Modified Logistic model to describe the progress of cumulative hydrogen production in batch tests. A concise model was proposed to describe the effects of nitrate concentration on average hydrogen production rate. 相似文献
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Wet air oxidation (WAO) is employed in this work for treating high concentration chemical wastewater containing phenol and/or phenolic compounds. Experimental results indicate that over 90% removal of phenol or phenolic compounds can be efficiently achieved in the WAO process. Despite of the high treatment efficiency of the WAO process, the treated wastewater, however, still retains relatively high chemical oxygen demand (COD) concentration and does not meet the safe discharge standard. Hence further treatment of the WAO treated wastewater by an aerobic biological treatment using acclimatized activated sludge is necessary. It is found in the present studies that the combined process, if appropriately operated, is capable of drastically reducing the COD concentration of the high concentration chemical wastewater to meet the safe discharge requirement. The operating conditions of the combined process are investigated to determine their respective effects on the overall treatment efficiency. The experimental data also indicate that the oxidation reaction can be represented by a first order kinetics in terms of the component or COD concentration. For both single component and multicomponent wastewaters, the WAO process was found to have different activation energy for oxidation below and above 200°C, suggesting possibly different reaction mechanisms between these temperature ranges. The experimental results provided in the present work can provide significant and practical information for optimizing the combined treatment method. 相似文献
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Shaoxia YANG Yu SUN Hongwei YANG Jiafeng WAN 《Frontiers of Environmental Science & Engineering》2015,9(3):436
Wet air oxidation (WAO) is one of effective technologies to eliminate hazardous, toxic and highly concentrated organic compounds in the wastewater. In the paper, multi-walled carbon nanotubes (MWCNTs), functionalized by O3, were used as catalysts in the absence of any metals to investigate the catalytic activity in the catalytic wet air oxidation (CWAO) of phenol, nitrobenzene (NB) and aniline at the mild operating conditions (reaction temperature of 155°C and total pressure of 2.5 MPa) in a batch reactor. The MWCNTs were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), gas adsorption measurements (BET), fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The functionalized MWCNTs showed good catalytic performance. In the CWAO of phenol over the functionalized MWCNTs, total phenol removal was obtained after 90 min run, and the reaction apparent activation energy was ca. 40 kJ·mol-1. The NB was not removed in the CWAO of single NB, while ca. 97% NB removal was obtained and 40% NB removal was attributed to the catalytic activity after 180 min run in the presence of phenol. Ca. 49% aniline conversion was achieved after 120 min run in the CWAO of aniline. 相似文献
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Artificial neural network and response surface methodology have been used to develop a model for simulation and optimization of the removal of Nile blue sulfate by heterogeneous Fenton oxidation. Experimental data were used to train an artificial neural network model with linear transfer function at the output layer and a tangent sigmoid transfer function at the hidden layer. A Box–Behnken design was employed to assess the effects of input process parameters on the total organic carbon removal. First order kinetics and lumped kinetics models were used to describe the reaction; a high regression coefficient indicated that the latter fitted best. The formation of non-oxidizable compounds was shown by liquid chromatography–mass spectrometry. 相似文献
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Xiang ZHANG Xiaogang GU Shuguang LU Zhouwei MIAO Minhui XU Xiaori FU Muhammad DANISH Mark L. BRUSSEAU Zhaofu QIU Qian SUI 《Frontiers of Environmental Science & Engineering》2016,10(3):502-512
Trichloroethene (TCE) degradation by Fe(III)-activated calcium peroxide (CP) in the presence of citric acid (CA) in aqueous solution was investigated. The results demonstrated that the presence of CA enhanced TCE degradation significantly by increasing the concentration of soluble Fe(III) and promoting H2O2 generation. The generation of HO? and O2-? in both the CP/Fe(III) and CP/Fe(III)/CA systems was confirmed with chemical probes. The results of radical scavenging tests showed that TCE degradation was due predominantly to direct oxidation by HO?, while O2-? strengthened the generation of HO? by promoting Fe(III) transformation in the CP/Fe(III)/CA system. Acidic pH conditions were favorable for TCE degradation, and the TCE degradation rate decreased with increasing pH. The presence of Cl-, HCO3-, and humic acid (HA) inhibited TCE degradation to different extents for the CP/Fe(III)/CA system. Analysis of Cl- production suggested that TCE degradation in the CP/Fe(III)/CA system occurred through a dechlorination process. In summary, this study provided detailed information for the application of CA-enhanced Fe(III)-activated calcium peroxide for treating TCE contaminated groundwater. 相似文献
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Co-present Pb(II) accelerates the oxidation of organic contaminants by permanganate: Role of Pb(III)
Lei Dong Pin Xie Xin Zhang Junlian Qiao Dandan Rao Yuankui Sun Xiaohong Guan 《Frontiers of Environmental Science & Engineering》2022,16(8):109
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Pentachlorophenol (PCP) in contaminated soil was removed by treatment with aqueous solutions of iron(III)-porphyrin complexes as catalysts and potassium monopersulfate (KHSO5) as the oxygen donor. The contaminated soils were artificially prepared by spiking PCP to the kaolin and ando soils. Three types of iron(III)-porphyrin complexes, tetra(?p-sulfophenyl) porphineiron(III) (Fe(III)-TPPS), tetra(N-methyl-4-pyridil)porphineiron(III) (Fe(III)-TMPyP) and heme, were examined, and Fe(III)-TPPS was found to be the most effective for removing PCP. Although the sequential addition of KHSO5 was examined, in an attempt to improve the efficiency of PCP removal, it was not effective. In a preliminary test of various aqueous solutions, the addition of humic acid (HA), with a lower degree of humification, led to a significant enhancement in PCP removal. When HA was added to the soil system, the percentages of PCP removal were increased by up to 10% compared to the absence of HA. Therefore, the addition of HA to the catalytic system was useful in enhancing PCP removal from contaminated soil. 相似文献
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Eunsung KAN Chang-Il KOH Kyunghyuk LEE Joonwun KANG 《Frontiers of Environmental Science & Engineering》2015,9(3):429
In the present study, the decomposition rates of carbon tetrachloride (CCl4) and 2,4-dichlorophenol (2,4-DCP) in water by the ultraviolet (UV) light irradiation alone and H2O2/UV were experimentally investigated. The detailed experimental studies have been conducted for examining treatment capacities of the two different ultraviolet light sources (low and medium pressure Hg arc) in H2O2/UV processes. The low or medium UV lamp alone resulted in a 60%–90% decomposition of 2,4-DCP while a slight addition of H2O2 resulted in a drastic enhancement of the 2,4-DCP decomposition rate. The decomposition rate of 2,4-DCP with the medium pressure UV lamp alone was about 3–6 times greater than the low pressure UV lamp alone. In the direct photolysis of aqueous CCl4, the medium pressure UV lamp had advantage over the low pressure UV lamp because the molar extinction coefficient of CCl4 at shorter wavelength (210–220 nm) is about 20 to 50 times higher than that at 254 nm. However, adding H2O2 to the medium pressure UV lamp system rendered a negative oxidation rate because H2O2 acted as a UV absorber being competitive with CCl4 due to negligible reaction between CCl4 and OH radicals. The results from the present study indicated significant influence of the photochemical properties of the target contaminants on the photochemical treatment characteristics for designing cost-effective UV-based degradation of toxic contaminants. 相似文献