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1.
Photocatalytic mineralization of glyphosate in a small-scale plug flow simulation reactor by UV/TiO2
Jian Q. Chen Zhi J. Hu Nan X. Wang 《Journal of environmental science and health. Part. B》2013,48(6):579-588
The present work involves the photocatalytic mineralization of glyphosate on a plug flow reactor by UV/TiO2. The effect of catalyst loading shows an optimal value (0.4 g L?1) which is necessary to mineralize glyphosate. The kinetic rate of glyphosate mineralization decreases with the increasing initial concentration of glyphosate, and the data can be described using the first-order model. An alkaline environment is conducive to glyphosate mineralization. The mineralization efficiency increases with elevated flow rate to 114 mL min?1, which is followed by a decrease with a further increase in flow rate due to the reduction of the residence time. The presence of external oxidants (K2S2O8, H2O2 and KBrO3) and photosencitizer (humic acid) can significantly enhance glyphosate mineralization. Photocatalysis oxidation ability of the three studied oxidants decrease in the order of: S2O8 2? > BrO3 ? > H2O2. Finally, the Langmuir–Hinshelwood (L-H) model was used to rationalize the mechanisms of reactions occurring on TiO2 surfaces and L-H model constants were also determined. 相似文献
2.
Ali R. Khataee Hamid R. Khataee 《Journal of environmental science and health. Part. B》2013,48(7):562-568
The present work deals with photooxidative removal of the herbicide, Acid Blue 9 (AB9), in water in the presence of hydrogen peroxide (H2O2) under UV light illumination (30 W). The influence of the basic operational parameters such as amount of H2O2, irradiation time and initial concentration of AB9 on the photodegradation efficiency of the herbicide was investigated. The degradation rate of AB9 was not appreciably high when the photolysis was carried out in the absence of H2O2 and it was negligible in the absence of UV light. The photooxidative removal of the herbicide was found to follow pseudo-first-order kinetic, and hence the figure-of-merit electrical energy per order (EEo) was considered appropriate for estimating the electrical energy efficiency. A mathematical relation between the apparent reaction rate constant and H2O2 used was applied for prediction of the electricity consumption in the photooxidative removal of AB9. The results indicated that this kinetic model, based on the initial rates of degradation, provided good prediction of the EEo values for a variety of conditions. The results also indicated that the UV/H2O2 process was appropriate as the effective treatment method for removal of AB9 from the contaminated wastewater. 相似文献
3.
采用O3/H2O2法对嘧啶废水进行处理,考察了不同反应条件对嘧啶和COD去除率的影响,并对O3/H2O2降解嘧啶的反应机制和动力学进行了初步探讨.实验结果表明,在pH值为11,反应时间为70 min,O3流量为4g/h,H2O2投加量为50 mmol/L的条件下,废水的嘧啶和COD的去除率分别达到86.46%和74.9... 相似文献
4.
为了有效地改善养猪场污水的质量,以H2O2为药剂,对污水进行了水浴加热和超声波辅助的对比实验,考察了超声波发生器输出端电流强度、处理时间、H2O2用量对污水的COD、氨气及颜色的影响,并进行正交实验优化。结果表明,超声波协同H2O2处理养殖污水是一种切实可行的方法,超声波协同H2O2处理污水的最佳工艺条件:电流0.7 A、处理时间2 min、H2O2用量3%,在此条件下降低COD量可达95%以上,氨氮的含量可降至14~15 mg/L,氨臭味大大得到了改善,并将原污水由黑色变为浅黄色。 相似文献
5.
天然沸石负载La2O3-ZnO-TiO2光催化降解活性艳红K-2BP 总被引:1,自引:1,他引:0
利用80目天然斜发沸石作载体制备La2O3(0.5%)-ZnO(20%)-TiO2/沸石复合光催化剂,以20 W紫外灯为光源,在自制的光催化反应器中降解活性艳红K-2BP,考察了光照时间、空气通入量、催化剂用量、溶液初始浓度、H2O2与Fe3+投加量等对活性艳红K-2BP光催化降解率的影响。结果表明,当溶液初始浓度为60 mg/L,催化剂投加量为12 g/L,通气量为1 200 mL/min,光照2.5 h,活性艳红K-2BP的降解率可达99.2%;H2O2和Fe3+投加量为4 mL/L和3 g/L时,光照1 h活性艳红K-2BP降解率分别为100%和97.2%。紫外可见吸收光谱显示,LZTZ光催化剂可有效降解印染废水。 相似文献
6.
微波辐射Bi2O3/沸石-H2O2体系降解废水中的硝基苯 总被引:2,自引:1,他引:1
研究了微波辐射下,以负载于沸石上的三氧化二铋为催化剂,以双氧水为氧化剂的催化氧化体系处理硝基苯工艺。通过单因素实验法,从反应催化剂负载量、pH、双氧水用量、微波功率、反应时间、催化剂用量等方面初步考察了硝基苯在该体系中的催化氧化效果。在氧化铋负载量3%(质量比),pH=2,2 mL 30%双氧水,火力为中火,催化剂投加量为0.7 g,反应2 min,对降解过程所得的中间产物和终产物进行了分析。结果表明,该体系对硝基苯的去除率能够达到99.2%,COD去除率为73.91%。 相似文献
7.
Asha Srinivasan Ping H. Liao 《Journal of environmental science and health. Part. B》2016,51(12):840-846
A newly designed continuous-flow 915 MHz microwave wastewater treatment system was used to demonstrate the effectiveness of the microwave enhanced advanced oxidation process (MW/H2O2-AOP) for treating dairy manure. After the treatment, about 84% of total phosphorus and 45% of total chemical oxygen demand were solubilized with the highest H2O2 dosage (0.4% H2O2 per %TS). The reaction kinetics of soluble chemical oxygen demand revealed activation energy to be in the range of 5–22 kJ mole?1. The energy required by the processes was approximately 0.16 kWh per liter of dairy manure heated. A higher H2O2 dosage used in the system had a better process performance in terms of solids solubilization, reaction kinetics, and energy consumption. Cost-benefit analysis for a farm-scale MW/H2O2-AOP treatment system was also presented. The results obtained from this study would provide the basic knowledge for designing an effective farm-scale dairy manure treatment system. 相似文献
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9.
Degradation of rhodamine B by Fe(0)-based Fenton process with H2O2 was investigated. The effects of H2O2 dose, Fe(0) dose, initial concentration of rhodamine B and initial pH value on the degradation of rhodamine B were examined. The results showed that the degradation and mineralization of rhodamine B occurred with low dose of H2O2 and Fe(0). The intermediates of rhodamine B were analyzed with UV-Vis spectrophotometry and ion chromatography and the mechanism of oxidative degradation of rhodamine B was also discussed. The reactive oxygen species (·OH) produced in Fe(0)-based Fenton process with H2O2 is the key to the degradation of rhodamine B by ways of N-de-ethylation, chromophore cleavage, ring-opening and mineralization. 相似文献
10.
Batch experiments were carried out to investigate the influences of H2O2/Fe(II) molar ratio, pH, sequence of pH adjustment, initial As(V) concentration, and interfering ions on As(V) removal in H2O2-Fe(II) process from synthetic acid mine drainage (AMD). The optimum H2O2/Fe(II) molar ratio was one for arsenate removal over the pH range of 4-7. Arsenate removal at pH 3 was poor even at high Fe(II) dosage due to the high solubility of Fe(III) formed in situ. With the increase of Fe(II) dosage, arsenate removal increased progressively before a plateau was reached at pH 5 as arsenate concentration varied from 0.05 to 2.0 mg L−1. However, arsenate removal was negligible at Fe/As molar ratio <3 and then experienced a striking increase before a plateau was reached at pH 7 and arsenate concentration ≥1.0 mg L−1. The co-occurring ions exerted no significant effect on arsenate removal at pH 5. The experimental results with synthetic AMD revealed that this method is highly selective for arsenate removal and the co-occurring ions either improved arsenate removal or slightly depressed arsenate removal at pH 5-7. The extended X-ray absorption fine structure (EXAFS) derived As-Fe length, 3.27-3.30 Å, indicated that arsenate was removed by forming bidentate-binuclear complexes with FeO(OH) octahydra. The economic analysis revealed that the cost of the H2O2-Fe(II) process was only 17-32% of that of conventional Fe(III) coagulation process to achieve arsenate concentration below 10 μg L−1 in treated solution. The results suggested that the H2O2-Fe(II) process is an efficient, economical, selective and practical method for arsenate removal from AMD. 相似文献
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12.
Fenton试剂法降解餐厨垃圾异味 总被引:1,自引:0,他引:1
自行设计Fenton试剂法降解还原性气体异味的反应器,研究了Fenton试剂法处理餐厨垃圾异味主要成分(苯、乙酸乙酯、苯乙烯)的降解效果。以苯为典型代表物,优化得出该实验的最佳反应条件为:pH=3,FeSO4.7H2O投加量为1 g/L液相,30%H2O2投加量为10 mL/L液相,紫外光源辅助。结果证明,Fenton试剂法处理单一异味气体的效果较理想,在前180 min内能达到90%以上,该法在处理气态异味污染物方面具有广阔的应用前景。 相似文献
13.
Bappaditya Kanrar Anjan Bhattacharyya 《Journal of environmental science and health. Part. B》2013,48(8):788-797
The photolysis of a rice herbicide Bispyribac sodium (Sodium 2, 6-bis [(4, 6-dimethoxypyrimidin-2-yl) oxy] benzoate) has been studied in different aqueous medium (distilled water, pond water and Irrigation water) under the influence of UV (λ max ≥ 250 nm) and sunlight in presence or absence of sensitizers (TiO2 and KNO3). The study was conducted under laboratory simulated condition which made it possible to evaluate the contribution of different factors viz. source of irradiation, solvent and sensitizers towards the photolysis of bispyribac sodium. The photodegradation proceeds via first order reaction Kinetics in all the cases. Five photo metabolites (M1-M5) were isolated in pure form by column chromatographic method from the irradiation system under UV influenced and TiO2 as sensitizer. From the different spectral data (IR, NMR, UV-VIS, Mass) the structure of these five metabolites were assigned as M1 (Phenol), M2 [2, 6-Dihydroxy benzoic acid], M3 [2, 6-bis [(4, 6 dimethoxypyrimidin-2yl) oxy] benzoic acid], M4 [2-(3-Hydroxy-phenoxy)-pyrimidine-4, 6-diol] and M5 as [2,4-Dihydroxy-3, 5-dimethoxy-6-(4-methoxy pyrimidine-2-yloxy)-benzoic acid]. Moreover, another six photometabolites (M6-M11) were identified from the different irradiation system on the basis of Micromass analysis. On the basis of MS/MS data analysis, the structure of these six photometabolites were assigned as M6 [2-(4, 6-Dimethoxy-pyrimidin-2-yloxy)-6-hydroxy-benzoic acid], M7 [2-Hydroxy-6-(4-hydroxy-6-methoxy-pyrimidin-2-yloxy)-benzoic acid], M8 [4, 6-Dimethoxy-pyrimidin-2-ol], M9 [6-Methoxy-pyrimidine-2, 4-diol], M10 [2-Hydroxy-6-(pyrimidin-2-yloxy)-benzoic acid] and M11 [2, 4, 6-Trimethoxy-pyrimidine]. The plausible Photodegradation pathways of bispyribac sodium in the present investigation were portrayed which proceeds via hydrolysis, hydrolytic cleavage, O-dealkylation, decarboxylation, dehydroxylation, O-alkylation and hydroxylation. 相似文献
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15.
A new Vis-Fe0-H2O2-citrate-O2 system comprising zero-valent iron, hydrogen peroxide, citrate anion and aeration at circumneutral pH under visible irradiation was studied. 21 μmol L−1 of Rhodamine B (RhB) was chosen as the substrate to be tested. Experiments were conducted under conditions of 2.9 mmol L−1 of H2O2, 12.6 g of Fe0 and 1.0 mmol L−1 of citrate at pH 7.5. Results showed that, in 1 h reaction, 54% of RhB was removed with corresponding 26% of COD reduced. Meanwhile, the amount of released dissolved irons from Fe0 surface was found to be at a very low level as <5.4 μmol L−1. Extinguishing tests with isopropanol suggested that RhB oxidation by hydroxyl radicals was the main process taken place in Vis-Fe0-H2O2-citrate-O2 system, which accounted for 75% of substrate removal in 3 h reaction. Control and factor influencing experiments showed that the prohibitive extents of individual factor importance on RhB removal followed a decreasing order of Fe0 > H2O2 > citrate > Vis > O2. This study showed an excellent system that could remove refractory organic compounds from water in laboratory researches, and also provided a good idea to reduce secondary contamination by dissolved irons in future investigations. 相似文献
16.
Pyrite is a common mineral at many mining sites. In this study, the mineral pyrite was studied as a Fenton-like reagent for environmental concerns. We selected lactate as a model target molecule to evaluate the Fenton-like catalytic efficiency of pyrite upon organic oxidation. A complete set of control experiments in both aerobic and anaerobic atmospheres unequivocally established that the pyrite in aqueous solution could spontaneously in situ generate OH and H2O2, serving as a Fenton-like reagent to catalyze the oxidation of lactate to pyruvate with no need for additional H2O2. We called it the pyrite-only Fenton-like (PF) reagent. Monitoring concentration changes of lactate and pyruvate with the time indicated that the pyrite mediated the favorable pyruvate formation at pH 4.5, 60 °C, under air atmosphere. The PF reaction could be stimulated by visible light illumination. Under the optimum conditions, up to 50% of lactate was degraded within 10 d. The results suggest that pyrite and its Fenton-like processes may be potentially practical in wastewater treatment. 相似文献
17.
Christian Hermans Ann C. Vandaele Michel Carleer Sophie Fally Réginald Colin Alain Jenouvrier Bernard Coquart Marie-France Mérienne 《Environmental science and pollution research international》1999,6(3):151-158
Absorption spectroscopy, which is widely used for concentration measurements of tropospheric and stratospheric compounds,
requires precise values of the absorption cross-sections of the measured species. NO2, O2 and its collision-induced absorption spectrum, and H2O absorption cross-sections have been measured at temperature and pressure conditions prevailing in the Earth’s atmosphere.
Corrections to the generally accepted analysis procedures used to resolve the convolution problem are also proposed. 相似文献
18.
Asko Noormets Olevi Kull Mark E. Kubiske 《Environmental pollution (Barking, Essex : 1987)》2010,158(4):992-999
The effect of elevated CO2 and O3 on apparent quantum yield (?), maximum photosynthesis (Pmax), carboxylation efficiency (Vcmax) and electron transport capacity (Jmax) at different canopy locations was studied in two aspen (Populus tremuloides) clones of contrasting O3 tolerance. Local light climate at every leaf was characterized as fraction of above-canopy photosynthetic photon flux density (%PPFD). Elevated CO2 alone did not affect ? or Pmax, and increased Jmax in the O3-sensitive, but not in the O3-tolerant clone. Elevated O3 decreased leaf chlorophyll content and all photosynthetic parameters, particularly in the lower canopy, and the negative impact of O3 increased through time. Significant interaction effect, whereby the negative impact of elevated O3 was exaggerated by elevated CO2 was seen in Chl, N and Jmax, and occurred in both O3-tolerant and O3-sensitive clones. The clonal differences in the level of CO2 × O3 interaction suggest a relationship between photosynthetic acclimation and background O3 concentration. 相似文献
19.
含聚丙烯酰胺采油污水的有效处理是近年来困扰油田三次采油生产的一个难题。研究采用移动床生物膜技术与O3/UV/H2O2高级氧化技术的组合方法来处理含聚丙烯酰胺采油污水。实验结果表明,移动床生物膜技术可以有效去除污水中的石油类有机物,但对聚丙烯酰胺几乎无效果。O3/UV/H2O2高级氧化技术可以降解污水中的聚丙烯酰胺。组合方法处理后的含聚丙烯酰胺采油污水水质可以达到污水综合排放标准中的一级要求。 相似文献
20.
Background, aim, and scope The pulp and paper industry is the sixth largest polluter discharging a variety of gaseous, liquid, and solid wastes into
the environment. Effluents from bleached Kraft mill effluents (BKME) are polluting waters to a great extent These effluents
cause considerable damage to the receiving waters if discharged untreated since they have high levels of biological oxygen
demand (BOD), chemical oxygen demand (COD), chlorinated compounds (measured as AOX), suspended solids (mainly fibers), fatty
acids, tannins, resin acids, lignin and its derivatives, sulfur and sulfur compounds, etc. This study aimed to remove adsorbed
organic halogen (AOX), total nitrogen, and lignin-degrading products in the wastewater (4,500 m3/h) from the paper mill in the pulp and paper industry, which is discharged to sea from a plant located in western Turkey.
Materials and methods The photocatalytic degradation of AOX, total nitrogen, and chlorinated lignin in BKME have been investigated in different
parameters, such as time, H2O2 and TiO2 concentration. In addition, for investigating the effect of chlorine on the removal of lignin, pure lignin solution was prepared
in equal amounts to chlorinated lignin degradation products found in BKME. The same experiments were conducted for this solution.
Experiments were carried out in photocatalytic reactor made of Pyrex glass. The mercury lamp was used as a radiation source.
All irradiation was carried out under constant stirring. The existence of dissolved O2 is an important factor which increases the photocatalytic degradation. Hence, we used an air pump for the aeration of the
wastewater solutions. The temperature of the wastewater was controlled and adjusted to 25°C by thermostat pump in conjunction
with a cooler. At the end of all experiments, AOX, total nitrogen and lignin concentrations were analyzed according to standard
methods. All experiments were performed in duplicate and average values were used.
Results and discussion When the effect of H2O2 and time were investigated, it was observed that the AOX concentration increased from 3.0 to 11.0 mg/L by only UV. However,
when H2O2 was added, AOX concentration decreased from approximately 3.0 to 0.0 mg/L. The optimal conditions for the removal of AOX
appear to be an initial H2O2 concentration of 20.0 mL/L and reaction time of 50 min. In addition, at the same experiment conditions, it was seen that
the total nitrogen concentration decreased from 23.0 to 15.0 mg/L by only UV and by increasing H2O2 concentration, the concentration of 20.0 mL/L H2O2 appears to be optimal (9.0 mg/L). The AOX, total nitrogen and lignin degradation products and pure lignin go through a minimum
when the concentration of H2O2 and TiO2 increases at constant pH and UV intensity. The kinetics for the degradation of AOX, total nitrogen and lignin degradation
products followed a pseudo-first order law with respect to the products, and the degradation rates (min−1) for the UV/TiO2/H2O2 system were higher than that of the corresponding values for the UV/H2O2 system.
Conclusions The AOX, total nitrogen and lignin concentration go through a minimum when the concentration of H2O2 and TiO2 increases at constant pH and UV intensity. It was found that the UV/TiO2/H2O2 system has proved capable of the degradation of total nitrogen as well as chlorinated and degraded lignin in BKME.
Recommendations and perspectives The photocatalytic process can be considered a suitable alternative for the remove of some compounds from the BKME. Nevertheless,
further studies should be carried out to confirm the practical feasibility of BKME. Another result obtained from the study
is that pre-purification carried out with UV/TiO2/H2O2 photocatalytic process may constitute an important step for further purification processes such as adsorption, membrane processes,
etc. 相似文献