Comparison of degradation reactions of Acid Yellow 61 in both oxidation processes of H_2O_2/UV and O_3

The comparison of degradation of Acid Yellow 61 as a model dye compound in both oxidation processes of H 2O 2/UV and O 3 has been studied. When the decolorization rate of Acid Yellow 61 in both reactions presented similar, it was found there are some differences from the results of AOX removal and production of inorganic ions and organic acids. The results reveal that the H 2O 2/UV has beneficial effect on mineralization than O 3 only for degradation of Acid Yellow 61 solution and it is possible for enhancement of method efficiency by taking longer reaction time and addition of high concentration of oxidants.

Advanced treatment of oil recovery wastewater from polymer flooding by UV/H_2O_2/O_3 and fine filtration

In order to purify oil recovery wastewater from polymer flooding （ORWPF） in tertiary oil recovery in oil fields, advanced treatment of UV/H2O2/O3 and fine filtration were investigated. The experimental results showed that polyacrylamide and oil remaining in ORWPF after the conventional treatment process could be effectively removed by UV/H2O2/O3 process. Fine filtration gave a high performance in eliminating suspended solids. The treated ORWPF can meet the quality requirement of the wastewater-bearing polymer injection in oilfield and be safely re-injected into oil reservoirs for oil recovery.

Explosion limits estimation and process optimization of direct propylene epoxidation with H2 and O2

Direct propylene epoxidation with H2 and O2,an attractive process to produce propylene oxide(PO),has a potential explosion danger due to the coexistence of flammable gases(i.e.,C3 H6 and H2)and oxidizer(i.e.,O2).The unknown explosion limits of the multi-component feed gas mixture make it difficult to optimize the reaction process under safe operation conditions.In this work,a distribution method is proposed and verified to be effective by comparing estimated and experimental explosion limits of more than 200 kinds of flammable gas mixture.Then,it is employed to estimate the explosion limits of the feed gas mixture,some results of which are also validated by the classic Le Chatelier’s Rule and flammable resistance method.Based on the estimated explosion limits,process optimization is carried out using commercially high and inherently safe reactant concentrations to enhance reaction performance.The promising results are directly obtained through the interface called gOPT in gPROMS only by using a simple,easy-constructed and mature packed-bed reactor,such as the PO yield of 13.3%,PO selectivity of 85.1%and outlet PO fraction of 1.8%.These results can be rationalized by indepth analyses and discussion about the effects of the decision variables on the operation safety and reaction performance.The insights revealed here could shed new light on the process development of the PO production based on the estimation of the explosion limits of the multi-component feed gas mixture containing flammable gase s,inert gas and O2,followed by process optimization.

Photocatalytic oxidation of nitric oxide from simulated flue gas by wet scrubbing using ultraviolet/TiO_2/H_2O_2 process

Nitric oxide(NO) from flue gas is hard to remove because of low solubility and reactivity. A new technology for photocatalytic oxidation of NO using ultraviolet(UV)/TiO2/H2O2 process is studied in an efficient laboratory-scale reactor. Effects of several key operational parameters on NO removal efficiency are studied, including TiO2 content, H2O2 initial concentration, UV lamp power, NO initial content, oxygen volume fraction and TiO2/H2O2 solution volume. The results illustrate that the NO removal efficiency increases with the increasing of H2O2 initial concentration or UV lamp power. Meanwhile, a lower NO initial content or a higher TiO2/H2O2 solution volume will result in higher NO removal efficiency. In addition, oxygen volume fraction has a little effect.The highest NO removal efficiency is achieved at the TiO2 content of 0.75 g/L, H2O2 initial concentration of 2.5 mol/L, UV lamp power of 36 W, NO initial content of 206×10-6 and TiO2/H2O2 solution volume of 600 m L. It is beneficial for the development and application of NO removal from coal-fired flue gas with UV/TiO2/H2O2 process.

Photolysis pathway of nitroaromatic compounds in aqueous solutions in the UV/H_2O_2 process

Nitroaromatic compounds such as nitrobenzene and nitrophenols are largely synthesised and particularly often occur in water bodies as toxic pollutants. The degradation of these compounds in the environment via direct photolysis and by biological treatment is difficult and usually slow. In our two previous published papers, we have discussed the advanced oxidation of nitrobenzene and nitrophenols in aqueous solutions irradiated by direct photolysis using polychromatic light and by means of UV/H2O2 process. The experimental results suggested the UV/H2O2 process is an effective and efficient technology for complete mineralization of these organic compounds. Based on the results therein, comprehensive reaction mechanism for nitrobenzene photolysis was proposed with detailed discussions.

Photodegradation of nitroaromatic compounds in aqueous solutions in the UV/H_2O_2 process

Photodegradation of nitrobenzene and nitrophenols in aqueous solutions by means of UV/H2 O2 process was studied in the Rayox batch reactors. Three nitrophenol isomers were identified as main photoproducts in the irradiated NB aqueous solutions. The distribution of nitrophenol isomers follows the order p-〉 m-〉 o-nitrophenol. Other intermediates detected include nitrohydroquinone, nitrocatechol, catechol, benzoquinone, phenol, nitrate/nitrite ions, formic acid, glyoxylic acid, maleic acid, oxalic acid and some aliphatic ketones and aldehydes. The degradation of nitrobenzene and nitrophenols at initial stages follows the first-order kinetics and the decay rate constants for nitrobenzene（NB） are around l0^-3-10^-2 s^-1 and for nitrophenols are around 10^-2 s^-1. The decomposition of H2 O2 in the presence of NB and each nitrophenol isomers follows zero-order kinetics. The quantum yields at initial stages for NB decay were estimated around 0.30 to 0.36, and for NPs decay is around 0.31-0.54.

Influence of coexisting substances on the photodegradation behaviors of 17α-ethinylestradiol (EE_2) in the UV/H_2O_2 process

The batch photodegradation reactor was used to investigate the influence of the common coexisting substances in wastewater,such as H+,anions (HCO3-,Cl-and NO3-) and organic compounds (methanol and bisphenol A),on the photodegradation behaviors of EE2 in the UV/H2O2 process.The results indicated that the addition of coexisting substances can influence the photodegradation behaviors of EE2 and it also follows the first-order kinetics.The acidic (pH 2-4) and alkaline (pH 10-12) medium benefit the photodegradation of EE2,but the photodegradation rate constant of EE2 keeps almost constant in the pH value of 4-10.The addition of anions,such as HCO3-,Cl-and NO3-,can inhibit the photodegradation of EE2,and the rate constant has a negative linear relationship with the concentration of the anions.However,the reduction degrees vary with the anions kinds,and the inhibition effect of the three anions is in the order of HCO3->NO3->Cl-.Addition of 5 mg/L methanol and bisphenol A can reduce the photodegradation rate constant of EE2by 84.31% and 72%,respectively.By comparison,the retardant effect of methanol is much more evident.In the studied concentrations range,the photodegradation rate constant of EE2 is the unary quadratic function of the organic compounds concentrations.

UV/H_2O_2光化学氧化降解对氯苯酚废水的反应动力学

研究了UV/H2 O2 体系降解对氯苯酚废水的过程及动力学 .结果表明 ,反应降解速率与双氧水加入量、污染物初始浓度及载气种类有关 .在双氧水理论投加量一半的情况下 ,通入氧气或空气 ,总酚的降解率可达到 96 % ,CODCr去除率接近 5 0 % .反应体系加入载气 ,显著影响污染物的去除率 .在本实验中 ,总酚降解为拟一级反应 .

UV-H_2O_2技术去除饮用水中微量有机污染物的应用

UV -H2 O2 技术是近 2 0年来处理饮用水中微量有机污染物的新方法。虽然该方法目前仍处在实验室试验阶段 ,但是由于该方法具有能有效去除水中微量有机污染物 ,避免二次污染等优点 ,因而在水污染防治中日益显示出广阔的前景。本文将对该方法的特点、研究现状及应用前景进行阐述 。

UV/H2O2/Cl2组合工艺处理含2-MIB滤后水的中试研究

针对饮用水中二甲基异莰醇(2-MIB)污染和UV/H2O2高级氧化工艺H2O2残留问题,构建了UV/H2O2/Cl2组合工艺,并以加标滤后水为原水开展了相关中试研究。基于响应曲面法对UV/H2O2工艺去除2-MIB进行参数优化,在此基础上对出水残留H2O2采用加氯中和处理,调整NaClO投加量以保证出水符合出厂水余氯要求。最终确定UV/H2O2/Cl2组合工艺运行的最优工况为:当2-MIB为275ng/L时,UV为350mJ/cm^2,H2O2投加量6mg/L,NaClO投加量7.5mg/L,在确定的最优工况下连续稳定运行组合工艺,对工艺出水进行检测,结果表明UV/H2O2/Cl2组合工艺对2-MIB去除率达到96.95%,出水余氯值0.4~0.5 mg/L,对TOC、UV254去除率分别达到15.59%、65.71%,能够氧化去除水中大分子有机物,对色氨酸等5种溶解性有机物去除效果良好,且不会带来消毒副产物超标和生物毒性问题,最终出水符合《生活饮用水卫生标准》(GB 5749-2006)对水质的要求。

UV-catalytic treatment of spent caustic from ethene plant with hydrogen peroxide and ozone oxidation

The performance of UV/H 2O 2, UV/O 3 and UV/H 2O 2/O 3 oxidation systems for treating spent caustic from an ethylene plant was investigated. In UV/H 2O 2 system, with the increase of H 2O 2 dosage, removal efficiencies of COD and the ratio of biochemical oxygen demand(BOD) to chemical oxygen demand(COD) of the effluent were increased and a better performance was obtained than the H 2O 2 system alone. In UV/H 2O 2 system, removal efficiency of COD reach 68% under the optimum condition, and BOD/COD ratio was significantly increased from 0 22 to 0 52. In UV/O 3 system, with the increase of O 3 dosage, removal efficiency of COD and BOD/COD ratio were increased, and a better performance was obtained than the O 3 system alone. Under the optimum condition, removal efficiency of COD was 54%, and BOD/COD ratio was significantly increased from 0 22 to 0 48. In UV/H 2O 2/O 3 system, COD removal efficiency was found to be 22.0% higher than UV/O 3 system.

Advanced glycation end products induce neural tube defects through elevating oxidative stress in mice

Our previous study showed an association between advanced glycation end products （AGEs） and neural tube defects （NTDs）. To understand the molecular mechanisms underlying the effect of AGEs on neural tube development, C57BL/6 female mice were fed for 4 weeks with com- mercial food containing 3% advanced glycation end product bovine serum albumin （AGE-BSA） or 3% bovine serum albumin （BSA） as a control. After mating mice, oxidative stress markers including malondialdehyde and H202 were measured at embryonic day 7.5 （E7.5） of ges- tation, and the level of intracellular reactive oxygen species （ROS） in embryonic cells was determined at E8.5. In addition to evaluating NTDs, an enzyme-linked immunosorbent assay was used to determine the effect of embryonic protein administration on the N-（carboxymethyl） lysine reactivity of acid and carboxyethyl lysine antibodies at E10.5. The results showed a remarkable increase in the incidence of NTDs at El0.5 in embryos of mice fed with AGE-BSA （no hyperglycemia） compared with control mice. Moreover, embryonic protein administration resulted in a noticeable increase in the reactivity of N-（carboxymethyl） lysine and N（ε）-（carboxyethyl） lysine antibodies. Malondialdehyde and H2O2 levels in embryonic cells were increased at E7.5, followed by increased intracellular ROS levels at E8.5. Vitamin E supplementation could partially recover these phenomena. Collectively, these results suggest that AGE-BSA could induce NTDs in the absence of hyperglycemia by an underlying mechanism that is at least partially associated with its capacity to increase embryonic oxidative stress levels.

UV/O_3/H_2O_2化学氧化活性艳蓝KN-R

以商品染料活性艳蓝KN -R为研究对象 ,利用UV/O3 /H2 O2 技术进行氧化处理。考察了染料溶液在此过程中的pH、电导率、COD、TOC和吸光度的变化。经过 70min的氧化过程 ,结果表明 ,溶液的pH降低、电导率不断升高、色度去除率达 98.9% ,溶液的COD和TOC去除率分别为 4 7%和 5 %。UV/O3 /H2 O2 技术与UV/H2 O2 氧化法相比 ,UV/O3 /H2 O2 能显著去除染料溶液的色度。

UV/H_(2)O_(2)高级氧化处理苯酚废水研究

本文采用UV/H_(2)O_(2)实验室装置对苯酚人工配水进行处理试验研究,试验结果表明:在UV灯功率为500W,pH值7.0左右,H_(2)O_(2):COD摩尔比为2:1,反应240min后COD由1045mg/L降至小于20mg/L,去除率高达99%以上。考察了不同pH(4.0,7.0和9.0),双氧水投加量与投加方式(一次投加和多次投加),以及氯离子浓度(0mg/L,2000mg/L和10000mg/L)对UV效果的影响,发现pH偏中碱性,H_(2)O_(2):COD摩尔比2:1且一次性投加有利于COD的降解,而正常情况氯离子浓度对UV/H_(2)O_(2)的效果影响不明显。

Cyanide removal for ultrafine gold cyanide residues by chemical oxidation methods

Because of the highly toxic cyanide in the gold cyanide residues,cyanide must be removed for environmental protection.The process mineralogy of residues was studied firstly,and then cyanide removal was carried out by three chemical methods.The results showed that the residue mainly contained Si,S and Fe.Pyrite was the main metallic mineral,and the iron-complex cyanides make cyanide removal difficult.The minerals in residues were in ultrafine particle size with high monomer dissociation degrees.In H_(2)O_(2)oxidation process,the self-decomposition and side reactions resulted in high consumption of H_(2)O_(2).In Na_(2)S_(2)O_(5)-air oxidation process,the time for complete process was long because of the reactions between Na_(2)S_(2)O_(5)and O_(2).Na_(2)SO_(3)oxidation method was found to be a new method for cyanide removal without air inflation device.The cyanide content was reduced to the national standard level in 90 min at pH 9.0 with optimum Na_(2)SO_(3)dose of 2.0 g/L.

Heterogeneous Degradation of Dyes in Industrial Effluent over Fenton-Like Nano-Fe₂O₃/Goldmine Complex

Nano-Fe2O3/goldmine complex was obtained by chemical coprecipitation reaction on the surface of goldmine waste-solid. Being used as the heterogeneous catalyst in Fenton-like advanced oxidation processes (AOPs), its treatment effect was studied in the removal performance of industrial dyes effluent. Although the maximal COD removal efficiency would reach 35.4% when 5 mL NaClO was added in 100 mL industrial dyes effluent, it is found that by using nano-Fe2O3/goldmine system, the COD removal efficiency of 13,000 mg/L dyes wastewater could reach up to 75.5% in the presence of 30 g/L nano-Fe2O3/goldmine complex and 50 mL/L NaClO at 50。C.

Effects of UV/Ag-TiO_2/O_3 advanced oxidation on unicellular green alga Dunaliella salina:Implications for removal of invasive species from ballast water

The UV/Ag-TiO2/O3 process was investigated for ballast water treatment using Dunaliella salina as an indicator. Inactivation curves were obtained, and the toxicity of effluent was determined. Compared with individual unit processes using ozone or UV/Ag-TiO2, the inactivation efficiency ofD. salina by the combined UV/Ag-TiO2/O3 process was enhanced. The presence of ozone caused an immediate decrease in chlorophyll a （chl-a） concentration. Inactivation efficiency and chl-a removal efficiency were positively correlated with ozone dose and ultraviolet intensity. The initial total residual oxidant （TRO） concentration of effluent increased with increasing ozone dose, and persistence of TRO resulted in an extended period of toxicity. The results suggest that UV/Ag-TiO2/O3 has potential for ballast water treatment.

UV/MgO_(2)体系对水体中双酚A的降解机制研究

双酚A(BPA)是一种典型的内分泌干扰物(EDCs),对人体和生物都存在毒性风险.高级氧化技术(AOPs)因其能产生大量的活性物种来降解污染物,成为目前处理环境中污染物最常用的方法之一.本研究采用紫外联合过氧化镁(UV/MgO_(2))体系降解水体中的BPA,并探究了该体系对BPA的降解机制.实验结果表明,UV/MgO_(2)体系能够高效降解水体中的BPA,在1 h内降解率可达98%,体系降解的反应速率对比单独MgO_(2)和单独UV降解分别提高了约48倍和18倍.数据显示在0.5 g·L^(-1)MgO_(2)浓度下BPA的降解速率最快.水体的pH、不同水体及水体中的不同离子对UV/MO_(2)体系降解BPA具有一定的影响作用(其中,SO_(4)^(2-)、HCO_(3)^(-)和HA有明显抑制作用),总体来说,体系的适应性较强.通过电子自旋共振(EPR)检测得知体系中存在·OH、^(1)O_(2)和O_(2)^(·-)3种自由基,其稳态浓度分别为6.475×10^(-14)、1.084×10^(-11)和4.605×10^(-9)mol·L^(-1),其中,O_(2)^(·-)为主导因子,贡献率约为90%.通过液相质谱(LC-MS/MS)对该体系降解BPA的产物进行了分析,初步推断出2条降解路径,主要是自由基攻击苯环的双键以及连接2个苯环的C—C键,使BPA得以降解.同时还对BPA的降解产物进行了毒性预测,结果表明,降解过程中BPA产物的生物毒性呈减小的趋势.本研究为UV/MgO_(2)技术的应用提供了理论依据.

Generating ^(1)O_(2) and Co^(IV)=O through efficient peroxymonosulfate activation by ZnCo_(2)O_(4)nanosheets for pollutant control

Heterogeneous advanced oxidation processes(AOPs)based on non-radical reactive species are considered as a powerful technology for wastewater purification due to their long half-lives and high adaptation in a wide pH range.Herein,we fabricate surface Co defect-rich spinel ZnCo_(2)O_(4)porous nanosheets,which can generate≡CoIV=O and ^(1)O_(2) over a wide pH range of 3.81-10.96 by the formation of amphoteric≡Zn(OH)2 in peroxymonosulfate(PMS)activation process.Density functional theory(DFT)calculations show Co defect-rich ZnCo_(2)O_(4)possesses much stronger adsorption ability and more electron transfer to PMS.Moreover,the adsorption mode changes from terminal oxygen Co-O-Co to Co-O,accelerating the polarization of adjacent oxygen,which is beneficial to the generation of≡CoIV=O and Generating ^(1)O_(2) .Co defect-rich ZnCo_(2)O_(4)porous nanosheets exhibit highly active PMS activation activity and stability in p-nitrophenol(PNP)degradation,whose toxicity of degradation intermediates is significant reduction.The Co defect-rich ZnCo_(2)O_(4)nanosheet catalyst sponge/PMS system achieved stable and efficient removal of PNP with a removal efficiency higher than 93%over 10 h.This work highlights the development of functional catalyst and provides an atomic-level understanding into non-radical PMS activation process in wastewater treatment.

Experimental and model comparisons of H_2O_2 assisted UV photodegradation of Microcystin-LR in simulated drinking water

The degradation of Microcystin-LR (MC-LR) in water by hydrogen peroxide assisted ultraviolet (UV/H2O2) process was investigated in this paper. The UV/H2O2 process appeared to be effective in removal of the MC-LR. MC-LR decomposition was primarily ascribed to production of strong and nonselective oxidant-hydroxyl radicals within the system. The intensity of UV radiation, initial concentration of MC-LR, MC-LR purity, dosages of H2O2, the initial solution pH, and anions present in water, to some extent, influenced the degradation rate of MC-LR. A modified pseudo-first-order kinetic model was developed to predict the removal efficiency under different experimental conditions.