Mineralization of dinitrotoluenes and trinitrotoluene of spent acid in toluene nitration process by Fenton oxidation

Fenton's reagent, UV/H2O2 and UV/Fenton's reagent were employed to mineralize dinitrotoluene (DNT) isomers and 2,4,6-trinitrotoluene (TNT) of spent acid in toluene nitration process. The bench-scale experiments were conducted to elucidate the influence of various operating variables on the performance of removal of total organic compounds (TOC) from spent acid, including reaction temperature, concentration of ferrous ion and H2O2 dosage. It is remarkable that organic compounds were completely mineralized by Fenton oxidation, of which removal efficiency is superior to that of UV/H2O2. Nevertheless, it makes slight difference between Fenton oxidation and UV/Fenton oxidation. According to the spectra identified by gas chromatograph/mass spectrometer (GC/MS), it is proposed that oxidative degradation of DNT isomers leads to o-, m-, p-mononitrotoluene (MNT) and 1,3-dinitrobenzene respectively. Besides, the oxidation of 2,4,6-TNT gives the 1,3,5-trinitrobenzene intermediate. Apparently, Fenton oxidation is promising for purification of spent acid industrially.     

对乙酰氨基酚制备过程中废水的处理

采用芬顿法、光催化氧化法与生物降解法相结合,研究对乙酰氨基酚制备过程中高浓度废水的降解。以COD的去除率为指标,研究各种方法的主要因素对废水降解效果的影响,通过控制单因素变量实验,确定各种方法的最佳工艺条件。结果表明,芬顿法的最佳工艺条件:废水的pH为4.0、FeSO4·7H2O加入量为0.10 mol/L、H2O2(30%)加入量为56.5 mL/L、反应时间3 h;光催化氧化降解废水的最佳条件:H2O2(30%)加入量4.5 mL/L,光照时间4 h。生物降解较适宜条件:pH为7.0,温度为28~29℃。在各种方法的最佳条件下,可使废水的COD从18 979.24 mg/L降至36.14 mg/L。     

电化学氧化法去除微污染水中的氨氮

以低氯离子浓度下微污染水中的氨氮(NH4+-N)为研究对象,采用电化学氧化法对污染水中的氨氮进行去除。通过静态和正交实验得到了极板的最佳运行参数。实验结果表明:Cl-浓度在各影响因素中对NH4+-N去除影响最大,且在其他影响因素不变的条件下,通过改变电解电流是解决动态运行时NH4+-N去除率下降较经济有效的方法。最佳运行工艺条件为:电流密度10 mA/cm2,电解时间10 min,极板间距1 cm,溶液初始pH为7,Cl-浓度100 mg/L,面体比102 m2/m3,氨氮的平均去除率在80%以上。     

活性炭-双氧水催化氧化法深度处理DSD酸废水的研究

以活性炭为催化剂、H2O2为氧化剂的催化氧化技术来处理DSD酸母液树脂吸附出水。处理效果比单纯的活性炭吸附或H2O2氧化要好的多。在温度25℃，线速度0．10m／h，pH3．50，H2O2添加量0．35％，处理500mL水样后，脱色率达到90%以上，TOC去除率达到40．0％以上。     

混凝沉淀工艺处理玻璃纤维生产废水试验研究

通过多种混凝剂对玻璃纤维生产废水进行混凝沉淀处理试验,结果表明,ＦｅＳＯ４．７Ｈ２Ｏ对玻纤废水具有较好的处理效果,并且探索了其处理的最佳工艺条件,在ＦｅＳＯ４．７Ｈ２Ｏ投加量为５００－８００ｍｇ／Ｌ,ＰＨ为６－１１时,出水各项指标均达到国家排标准。     

吹脱-电化学催化氧化组合工艺去除地下水中氨氮

以上海某钢铁工业区固废堆场氨氮污染的地下水为研究对象,研究了单独电化学氧化法、光/电协同氧化法、吹脱-电化学催化氧化组合法对氨氮的去除效果,提出能高效除氨氮且适合工程实际应用的吹脱-电催化氧化组合工艺。结果表明,相较单独电化学氧化,光/电协同氧化体系中的强氧化活性物质(HO·、HOCl、ClO⁻等)通过自由基链式反应和光解反应生成氧化性更弱的ClO·,反而削弱氨氮去除效果。而吹脱-电催化氧化组合工艺下氨氮、总氮的去除率分别为97.62%、90.23%,出水满足《地下水质量标准》(GB/T 14818-2017)IV类标准。电子顺磁共振(EPR)和活性氯生成实验证实HO·和活性氯(HOCl、ClO⁻、Cl₂)在氨氮转化过程中的重要作用。本实验为进一步研究和设计基于电化学法处理废水中的氨氮技术和组合工艺提供了理论依据。     

Abatement of sulfur hexafluoride emissions from the semiconductor manufacturing process by atmospheric-pressure plasmas

Sulfur hexafluoride (SF6) is an important gas for plasma etching processes in the semiconductor industry. SF6 intensely absorbs infrared radiation and, consequently, aggravates global warming. This study investigates SF6 abatement by nonthermal plasma technologies under atmospheric pressure. Two kinds of nonthermal plasma processes--dielectric barrier discharge (DBD) and combined plasma catalysis (CPC)--were employed and evaluated. Experimental results indicated that as much as 91% of SF6 was removed with DBDs at 20 kV of applied voltage and 150 Hz of discharge frequency for the gas stream containing 300 ppm SF6, 12% oxygen (O2), and 40% argon (Ar), with nitrogen (N2) as the carrier gas. Four additives, including Ar, O2, ethylene (C2H4), and H2O(g), are effective in enhancing SF6 abatement in the range of conditions studied. DBD achieves a higher SF6 removal efficiency than does CPC at the same operation condition. But CPC achieves a higher electrical energy utilization compared with DBD. However, poisoning of catalysts by sulfur (S)-containing species needs further investigation. SF6 is mainly converted to SOF2, SO2F4, sulfur dioxide (SO2), oxygen difluoride (OF2), and fluoride (F2). They do not cause global warming and can be captured by either wet scrubbing or adsorption. This study indicates that DBD and CPC are feasible control technologies for reducing SF6 emissions.     

Treatment of trinitrotoluene by crude plant extracts

Crude plant extract solutions (spinach and parrotfeather) were prepared and spiked with 2,4,6-trinitrotoluene (TNT) (20 mgl(-1)). 90-h TNT removal by these solutions was compared to controls. Spinach and parrotfeather extract solutions removed 99% and 50% of the initial TNT, respectively; TNT was not eliminated in the controls or in extract solutions where removal activity was deactivated by boiling. A first-order removal constant of 0.052 h(-1) was estimated for spinach extract solutions treating 20 mgl(-1) TNT concentrations, which compared favorably to intact plant removal. Concentration variation was described by Michaelis-Menton kinetics. Detectable TNT degradation products represented only a fraction of the total TNT transformed, and the transformation favored the formation of 4-aminodinitrotoluene. The results indicated that crude plant extracts transform TNT, without the presence of the live plant.     

微波作用下氧化碱浸铜冶炼烟灰脱砷的动力学

采用微波氧化辅助Na2S-NaOH浸出体系对铜冶炼烟灰（简称"烟灰"）进行研究。结果表明：当温度60℃,NaOH和烟灰的投加量比例为5 g：10 g,Na2S和烟灰的投加量比例为8 g：10 g,固液比为1：20时,砷的浸出率为98.45%。动力学研究表明：砷的浸出过程在313~343 K内符合"未反应收缩核"模型,浸出过程受未反应核周围残留固体膜层扩散控制,经拟合得出浸出动力学方程,浸出表观活化能Ea=13.46 kJ·mol-1。     

电-Fenton法处理制药中间体废水的研究

采用电-Fenton法对麻醉药瑞芬太尼合成过程中的中间体1-苄基-4-氨甲酰基-4-苯胺基哌啶(简称酰胺,AMIDE)模拟废水进行了降解研究,结果表明,在以石墨为阴极、铁为阳极的模式下,当pH为3、电解电压为3 V、投加H_2O_2浓度为10 mmol/L时,室温下电解浓度为20 mg/L的酰胺废水60 min后,酰胺的去除率高于99%,TOC去除60%。通过紫外光谱(UV)、红外光谱(IR)及HPLC检测酰胺的降解产物,说明电-Fenton法能使废水中目标化合物的环结构破坏,快速而完全地转化为小分子,但不能使其全部矿化。本研究可为电-Fenton法在处理该类药物合成废水中的实际应用提供重要的理论依据。     

气田高浓度含硫废水的化学氧化处理

采用亚硫酸钠(Na2SO3)氧化法对气田高含硫废水进行了实验研究.考察了硫化物初始浓度、Na2SO3/Na2S(摩尔比)、初始pH值和反应时间对Na2SO3氧化去除硫化物效果的影响,进行了对氧化产物的元素分析.结果表明,在Na2SO3/Na2S(摩尔比)为0.7、初始pH值为5和反应时间为5 min时,硫化物从1 100 mg/L降至1.80 mg/L,去除率高达99.84%,达到了气田回注水水质标准.元素分析发现,氧化产物中C、N、S、H和O元素的含量分别为0.11%、0.06%、98.73%、0.90%和1.10%,且其产率达到90.59%.     

沉淀-电解氧化法处理高铁氰化废水

采用沉淀-电解氧化联合技术处理高铁氰化提金废水,重点考察了沉淀剂添加量、沉淀时间、温度、电解电压、电解时间等因素对总氰、游离氰和铁氰络合物去除率的影响。结果表明,随着CuCl₂加入量的增大,氰化废水中各主要离子的沉淀率逐步增加。常温下向100 mL含氰废水中加入3.0 g CuCl₂并搅拌40 min后,总氰(CN_T)、CN⁻、Fe离子的去除率分别可达到95.29%、98.00%与100%。以钛板为阴阳极,采用一阴两阳体系对沉淀后液进行电解氧化实验,当电压为6 V、极间距为15 mm、电解时间为5 h、初始浓度为60%的条件下,CN_T和CN⁻的去除率最高可达到99.76%和99.90%。XRD分析表明,沉淀过程中铜氰、铁氰络合离子的去除主要归因于CuCN、Cu₂Fe(CN)₆、CuSCN等沉淀的形成。电解氧化过程中随着外加电压与氯离子浓度的增大,废水中残存的游离氰与金属氰络合离子的去除率逐渐增加,这主要是阳极反应产生的Cl₂/ClO⁻等强氧化剂作用的结果。以上研究结果可为高铁氰化提金废水的综合处理提供参考。     

电-Fenton法预处理干法腈纶生产废水

以Ti金属网为阴极,Ti基RuO2涂层形稳电极为阳极,采用外加H2O2和Fe2+的方式,研究了电-Fenton氧化预处理干法腈纶生产废水的工艺,考察了H2O2投加量、Fe2+投加量、pH值和电流强度等因素对污染物降解过程的影响,分析了废水可生化性和污染物变化规律。结果表明,电-Fenton法可以有效降解废水中有机污染物,使废水COD迅速降低,在初始pH值为3.0,Fe2+投加量为5.0 mmol/L,H2O2投加量为60.0 mmol/L,电流强度0.2 A的条件下,反应120 min后COD去除率可以达到44.0%以上;反应过程中H2O2的投加方式对电-Fenton法的处理效果具有明显影响,H2O2分6次投加可以使COD去除率由一次性投加时的44.8%提高至54.1%;处理后废水的BOD5/COD由0.29升高至0.68;GC-MS结果表明,经电-Fenton法预处理后,废水中多数芳香族化合物和特征污染物能被有效降解。     

电化学氧化法处理垃圾渗滤液纳滤浓缩液

实验利用电化学氧化法处理垃圾渗滤液纳滤浓缩液,以提高废水的可生化性。研究考察了水力停留时间、进水流量、循环流量、电流强度和原水氯离子浓度对有机物去除的影响。研究结果表明,电化学氧化法的最佳运行条件如下:水力停留时间为 3 h,进水流量为1 m3/h,循环流量为15 m3/h,电流强度为420 A。在上述条件下,原水COD浓度从3 100 mg/L降到1 311.3 mg/L,去除率达到57.7%,BOD/COD值由0.03提升至0.31。氯离子对电解有促进作用,但原水氯离子浓度超过5 000 mg/L,不需要外加工业盐。     

Fenton氧化水中间氯硝基苯的动力学与机制研究

结合Fenton氧化反应动力学模型研究了Fenton氧化水中间氯硝基苯(m-ClNB)的影响因素和降解机制.结果表明:(1)反应初始pH、H2O2浓度、Fe2+浓度、污染物初始浓度和反应温度对m-ClNB的降解均有明显影响.在反应初始pH为3.5、m-ClNB初始摩尔浓度为0.444mmol/L、H2O2摩尔浓度为21.55mmol/L、Fe2+摩尔浓度为0.054mmol/L、反应温度为(25土1)℃的条件下,m-ClNB的去除效果较好.(2)建立了Fenton氧化m-ClNB的准一级反应动力学模型,且m-ClNB的降解与该模型拟合良好.基于不同反应温度时的准一级反应速率常数(kap),得到了m-ClNB降解的阿累尼乌斯公式,且活化能为36.51kJ/mol.(3)气相色谱(GC)/质谱(MS)和高效液相色谱(HPLC)/MS分析表明,Fenton氧化m-ClNB的主要产物有4-氯-2-硝基苯酚及其同分异构体、羟基乙酸、草酸、丁二酸、丙二酸、6-氯己酸、乙醛酸、2,2-二羟基丙二酸和2-乙基丙二酸等.     

光催化氧化处理有机废水

介绍了光催化氧化法的原理,对光催化氧化法处理有机废水的可行性进行了试验,探讨了ＣＯＤ随反应时间的变化规律及催化剂用量,温度、浓度的影响。试验表明,光催化氧化可降解象洗涤剂这样难降解的有机物,反应１２０ｍｉｎＣＯＤ去除率可达５０％以上。     

紫外催化湿式氧化工艺降解油墨废水

为了解决传统催化湿式过氧化氢氧化技术需要高温高压等苛刻条件的问题,将紫外引入催化湿式氧化技术,得到可在常温常压条件下进行的紫外催化湿式氧化工艺(UV-CWOP)。以Cu2+为催化剂,采用该工艺处理油墨废水取得了良好的效果。通过单因素实验确定的最佳工艺条件为:pH值=3,H2O2用量为1.5倍理论量,CuSO4.5H2O投量2 g/L,初始温度40℃。在此条件下处理油墨废水3 h,COD可从9 500 mg/L降解到89 mg/L,出水达到国家《污水综合排放标准》(GB8978-1996)一级标准。     

超临界水氧化方法处理含酚废水

在亚临界及超临界条件下,在间歇式、连续式反应器中研究了温度、压力、停留时间对苯酚去除率的影响。发现在其他条件不变的情况下,随反应温度和压力的升高,停留时间的延长,苯酚的去除率提高;在很短的停留时间内,苯酚的去除率可达９６％以上。对苯酚氧化中间产物的研究证明了该技术的氧化彻底性。     

Decomposition of gas phase 1,3-butadiene by ultraviolet/ozone process

A pilot-scale plug-flow reactor was built to investigate its performance in treating airborne 1,3-butadiene (BD) via ozonation (O3) and ultraviolet (UV)/O3 technologies. Governing factors, such as the initial molar ratio of ozone to BD, UV volumetric electric input power, and moisture content in the influent airstream, were investigated. Experiments were conducted at an influent BD concentration of approximately 50 ppm, an ambient temperature of 26 degrees C, and a gas retention time of 85 sec. Results show that an initial molar ratio of ozone to BD of 3.5 and 2 sufficed to obtain BD decompositions of >90% for ozonation and UV/O3, respectively. The UV irradiance did not directly promote the decomposition of BD, rather, it played a role in promoting the production of secondary oxidants, such as hydroxyl radicals. Kinetic analyses indicate that both types of BD decomposition are peudo-first-order with respect to BD concentrations. Moisture content (relative humidity = 40-99%) and UV volumetric electric input power (0.147 and 0.294 W/L) are both factors that weakly affect the rate of BD decomposition. Economic evaluation factors, including both energy of ozone production and UV electric input power, were also estimated.