TNT在超临界水中的氧化反应动力学

利用超临界水氧化(SCWO)实验装置,氧气为氧化剂,对废水中的TNT在超临界水中的氧化反应进行了研究,用幂函数法则建立了COD去除率宏观动力学方程。结果表明,SCWO技术可有效消除废水中的TNT,随着反应温度的升高和停留时间的延长,TNT模拟废水的COD去除率显著增大。在温度为673~823K、压力24MPa、300%过氧量、TNT浓度为5.7×10-4mol/L的实验条件下,有机物的反应级数为1.18,活化能Ea为96.85kJ/mol,指前因子A为4.87×103s-1。     

超临界水氧化法处理醇类废水(Ⅰ)处理效果及过程参数的影响

研究了以超临界水氧化法（ ＳＣＷＯ）处理乙醇废水的过程。实验表明,一氧化碳和二氧化碳分别是反应中间产物和最终产物。５５０℃、２５ＭＰａ、停留时间大于１０ｓ时,ＳＣＷＯ能将乙醇完全氧化为二氧化碳,达到彻底处理的目的。随停留时间增大、温度升高,乙醇的去除率增大,而压力和氧气浓度的变化对过程没有显著影响。     

连续式超临界水氧化装置处理苯酚溶液的动力学讨论

本文利用自建的一套连续式装置进行了苯酚的超临界水氧化研究。在高于水的临界点的温度和压力 (5 73～ 873 ,2 5～ 35 MPa)下 ,用氧气作为氧化剂对苯酚溶液进行氧化处理。对影响苯酚分解转化率的各种因素如停留时间、温度、压力、氧化剂浓度及苯酚初始浓度等进行了条件实验 ,研究了超临界水氧化处理苯酚时的去除动力学。在实验条件下 ,溶液中苯酚的去除动力学对苯酚是一级、氧气是零级 ;其速率常数与温度的关系符合 Arrhenius公式 ;压力也明显影响速率常数 ,随压力升高而增大     

用超临界水氧化技术降解废水中的TNT

利用超临界水氧化(SCWO)实验装置,研究了不同工艺条件下超临界水氧化技术对废水中TNT的降解规律.结果表明,采用超临界水氧化技术可以有效去除废水中的TNT.反应温度、停留时间是影响TNT降解效果的主要因素,随着反应温度、停留时间的增加,TNT的降解率显著增大.在反应温度为550℃、压力24MPa、反应时间120s的条件下,废水中TNT的降解率可以达到99.9%.通过色谱-质谱(GC-MS)联用对超临界水氧化降解TNT的中间产物进行了分析.结果表明,中间产物主要有三硝基苯、甲苯、硝基苯酚、萘、芴、菲、蒽、邻苯二甲酸正丁酯和庚烷、十二烷、十四烷等直链饱和烷烃,证实SCWO降解TNT的同时,发生了偶合、水解、异构化等副反应.探讨了TNT在超临界水中的氧化反应机理.     

超临界水氧化处理DDNP废水的动力学研究

采用间歇式超临界水氧化实验装置,以O2为氧化剂,在703～823 K、压力24 MPa、停留时间10～50 s的条件下,进行了超临界水氧化DDNP模拟废水实验,COD去除率可达99%;建立了COD去除率宏观动力学方程.结果表明,超临界水氧化对处理DDNP是有效的,在超临界条件下,DDNP废水的COD去除率随着反应温度的升高和停留时间的延长而增加;在氧化剂过量2倍的情况下,DDNP超临界水氧化反应对有机物的反应级数为1.33级,对氧气为0.21级;反应活化能Ea为30.7 kJ/mol,指前因子A为61.97.     

双氧水超临界氧化对氨基苯酚模拟废水

在连续流管式反应器中，以H2O2为氧化剂，在温度480~550℃、压力32~38 MPa及H2O2过量100%~270%的条件下，用超临界水氧化(Supercritical water oxidation，简称SCWO)对含对氨基苯酚的模拟废水进行了实验研究.结果表明，采用SCWO法能有效去除废水中的含氮有机物对氨基苯酚. 升高温度、升高压力和延长停留时间使COD去除率显著提高. 在550℃, 38 MPa, H2O2过量190%和停留时间229 s时，COD去除率高达98.5%. 在此条件下，SCWO总动力学对COD是2.13级，反应的活化能为29.3 kJ/mol.     

城市污泥超临界水氧化及反应热的实验研究

研究了间歇式反应器中城市污泥的超临界水氧化反应(SCWO).实验表明:污泥COD去除率可达到99.98%以上,随反应时间增加、温度升高,污泥COD去除率显著增大;压力对过程无显著的影响;氧化剂过量倍数小于一定程度时,对污泥的去除率影响显著,超过此值时则几乎没有影响.应用SCWO能快速实现污泥的减量减容和无害化处理,脱水污泥完全氧化后的残余固体质量仅为脱水污泥的8%;在450℃,经过95 s的反应时间后,反应液的化学需氧量即可小于40 mg·L-1.此外,藉反应介质焓值的变化探索了污泥SCWO的反应热,获得了反应过程中能量平衡时,污泥的最大含水率和最小有机物质量含量的方程.结果表明:污泥中有机物完全氧化释放的反应热为21319.15kJ·kg-1,在400℃、26 MPa条件下,当污泥中有机物质量含量超过3.0%时,SCWO反应即能实现能量的平衡--自热.     

基于硝酸钠超临界水氧化技术处理磷酸三丁酯的实验研究

放射性磷酸三丁酯是一种常见的放射性有机废物,其妥善处理对于核工业的可持续发展极为重要。采用连续式超临界水氧化设备,以硝酸钠为氧化剂对磷酸三丁酯的氧化分解进行了探究。结果表明：磷酸三丁酯降解产物无毒害物,气相产物为N₂、CO₂,液相产物中含有NO₃^-、PO₄^3-及未反应的有机物,证实了以硝酸钠为氧化剂超临界水氧化技术处理磷酸三丁酯的可行性。通过对反应温度、反应压力、停留时间等因素对有机物去除率影响的研究,确定了磷酸三丁酯超临界水氧化反应的最优化反应条件：反应温度500℃、反应压力22.5 MPa、过氧系数1.5、停留时间55.7 s。在此条件下,有机物去除率达到95%以上。     

超临界水氧化处理含酚废水试验研究

在超临界水氧化系统中，以过氧化氢为氧化剂，研究了含酚废水的氧化作用及效果。在试验条件下，废水中有机物能够被显著降解。过氧化氢用量、体系的温度、压力、反应停留时间对有机物去除率有不同程度的影响。随着过氧化氢用量增加、体系温度、压力的升高，反应停留时间的延长，有机物去除率有明显的增加。当实际加入的过氧化氢量与理论需要量的比值K=2．0，系统压力为30MPa，温度超过450℃，反应停留时间超过190s时，COD去除率可接近100％。     

超临界水氧化法用于水质总有机碳含量检测

利用超临界水氧化法(SCWO)与非色散红外法(NDIR)相结合对葡萄糖水溶液总有机碳(TOC)含量进行连续检测.在超临界水氧化条件下,测试水样中初始有机物的浓度与红外检测信号具有良好的线性关系,表明此方法用于检测TOC含量切实可行.并研究了温度、压力、氧化剂浓度对检测结果的影响.实验结果表明,升高温度和压力均有利于提高...     

超临界水氧化处理DDNP废水的动力学研究

采用间歇式超临界水氧化实验装置，以O2为氧化剂，在703-823K、压力24MPa、停留时间10-50s的条件下，进行了超临界水氧化DDNP模拟废水实验，COD去除率可达99％；建立了COD去除率宏观动力学方程。结果表明，超临界水氧化对处理DDNP是有效的，在超临界条件下，DDNP废水的COD去除率随着反应温度的升高和停留时间的延长而增加；在氧化剂过量2倍的情况下，DDNP超临界水氧化反应对有机物的反应级数为1．33级，对氧气为0．21级；反应活化能E。为30．7kJ／mol，指前因子A为61．97。     

Oxidation characteristics of phthalic and adipic acids by supercritical water

Supercritical water oxidation (SCWO) was carried out in a flow-type reactor for modeling of waste-water containing phthalic or adipic acid. For each acid, the reaction order and rate constant, k, were determined over a wide range of experimental conditions : temperatures from 633.15 to 713.15 K, pressures from 18 to 29 MPa, excess amounts of hydrogen peroxide from zero to 800 percent, and the mean residence time in the reactor from 1.1 to 49.1 seconds. The concentration of both acids in model wastewater was set by 500 ppm. For phthalic acid, we found that the orders of decomposition reaction with respect to the reactant concentrations were 0.56 for phthalic acid, 0.31 for hydrogen peroxide, and 0.53 for water. For adipic acid, the orders of oxidation were 0.78 for adipic acid, 0.53 for hydrogen peroxide, and 0.74 for water. Then measured activation energy for phthalic acid was 33.08 kcal/mol and that for adipic acid was 19.51 kcal/mol, respectively.     

Treatment of dyehouse waste‐water by supercritical water oxidation: a case study

BACKGROUND: Supercritical water oxidation (SCWO) of dyehouse waste‐water containing several organic pollutants has been studied. The removal of these organic components with unknown proportions is considered in terms of total organic carbon concentration (TOC), with an initial value of 856.9 mg L^?1. Oxidation reactions were performed using diluted hydrogen peroxide. The reaction conditions ranged between temperatures of 400–600 °C and residence times of 8–16 s under 25 MPa of pressure. RESULTS: TOC removal efficiencies using SCWO and hydrothermal decomposition were between 92.0 and 100% and 6.6 and 93.8%, respectively. An overall reaction rate, which consists of hydrothermal decomposition and the oxidation reaction, was determined for the hydrothermal decomposition of the waste‐water with an activation energy of 104.12 ( ± 2.6) kJ mol^?1 and a pre‐exponential factor of 1.59( ± 0.5) × 10⁵ s^?1. The oxidation reaction rate orders for the TOC and the oxidant were 1.169 ( ± 0.3) and 0.075 ( ± 0.04) with activation energies of 18.194 ( ± 1.09) kJ mol^?1, and pre‐exponential factor of 5.181 ( ± 1.3) L^0.244 mmol^?0.244 s^?1 at the 95% confidence level. CONCLUSION: Results demonstrate that the SCWO process decreased TOC content by up to 100% in residence times between 8 and 16 s under various reaction conditions. The treatment efficiency increased remarkably with increasing temperature and the presence of excess oxygen in the reaction medium. Color of the waste‐water was removed completely at temperatures of 450 °C and above. Copyright © 2010 Society of Chemical Industry     

Hydrogen production from bioethanol reforming in supercritical water

Hydrogen production by reforming and oxidative reforming of ethanol in supercritical water (SCW) at the intermediate temperature range of 500-600 °C and pressure of 25 MPa were investigated at different ethanol concentrations or water to ethanol ratios (3, 20 and 30), with the absence and the presence of oxygen (oxygen to ethanol ratio between 0 and 0.156). Hydrogen was the main product accompanied with relatively low amounts of carbon dioxide, methane and carbon monoxide. Some liquid products, such as acetaldehyde and, occasionally, methanol were present. The ethanol conversion and hydrogen yield and selectivity increased substantially as the water to ethanol ratio and the reaction temperature increased. Ethanol was almost completely reformed and mainly converted to hydrogen giving a H₂/CO ratio of 2.6 at 550 °C and water to ethanol ratio of 30 without carbon formation. Coke deposition was favored at low water to ethanol ratio, especially at high temperatures (≥550 °C). The hydrogen yield improved as the ethanol was partially oxidized by the oxygen added into the feed at oxygen to ethanol ratios <0.071. It was evidenced that the metal components in Inconel 625 reactor wall reduced by a hydrogen stream acted as a catalyst promoting hydrocarbon reforming as well as water-gas-shift reactions while dehydrogenation of ethanol forming acetaldehyde can proceed homogeneously under the SCW condition. However, at high oxygen to ethanol ratio, the reactor wall was gradually deactivated after being exposed to the oxidant in the feed. The loss of the catalytic activity of the reactor surface was mainly due to the metal oxide formation resulting in reduction of catalytic activity of the reactor wall and reforming of carbon species was no longer promoted.     

Catalytic Olefin Epoxidation With H2O2 in Supercritical CO2. Synergic Effect by Hexafluoroacetone and Manganese‐Porphyrins

The heterogeneous oxidation of cyclooctene with hydrogen peroxide catalyzed by manganese 5,10,15,20‐tetrakis(2′,6′‐dichlorophenyl)porphyrinate, in the presence of hexafluoroacetone hydrate as co‐catalyst, has been studied in supercritical carbon dioxide, at 40 °C and 20 MPa. Under proper conditions, a complete olefin conversion may be obtained with the formation of cyclooctene oxide as the sole product. Fixation by hexafluoroacetone into its perhydrate derivatives provides a useful system to solubilize hydrogen peroxide in supercritical carbon dioxide, and to hamper catalyst bleaching and oxidant decomposition. Moreover, in the presence of both manganese‐porphyrin and hexafluoroacetone, the reaction rates are enhanced. Among the factors that may increase yields and rate of conversion, the use of a Teflon‐coated steel reactor rather than an uncoated one proved to be quite relevant, thus indicating the occurrence of a parasite radical decomposition of hydrogen peroxide promoted by steel reactor walls.     

Supercritical water oxidation of nitrogen compounds with multi-injection of oxygen

A supercritical water oxidation (SCWO) process with oxidant multi-injection was studied in a continuous flow system in which the same amount of oxidant feed is split between two points – a first injection at the reactor inlet and a second injection at one of the three different positions along the reactor. Under the same operating conditions, this multi-injection configuration showed advantages over the system with a single oxidant entry. Moreover, oxidant dosage in a SCWO reactor is a key aspect in energy management.In this work, experiments were performed to find the best oxidant dosage to obtain the maximum organic conversion. Experiments were carried out using N,N-dimethylformamide (DMF) as a model compound for nitrogen-containing hydrocarbons in wastewaters. All experiments were carried out at 250 bar with an oxygen coefficient n = 1 and a temperature of 400 °C. Each experiment was carried out at five different residence times (2, 4, 6, 8 and 10 s). Once the best configuration had been determined, the effect of temperature (400–550 °C), initial organic concentration (5–30 mM), oxygen coefficient (0.5–3) and residence time (2–10 s) was investigated in the SCWO process of DMF.     

Effect of NaOH on the decomposition of halogenated hydrocarbon by supercritical water oxidation

To protect alloys from corrosion phenomena in the supercritical water oxidation (SCWO) process, the effects of neutralizer on the conversion and corrosion were investigated. The surface morphologies of all the alloy coupons exposed to 2,4-Dichlorophenol (2,4-DCP) in the SCWO were significantly changed in microscopic images. The theoretical amount of NaOH as a neutralizer was calculated under the assumption of complete oxidation of 2,4-DCP. The pre-dosed NaOH in the range of 100% to 300% stoichiometric amount could not affect significantly the pH value in the SCWO. Moreover, the pH = 7 was not achieved until 700% stoichiometric amount of NaOH was pre-dosed to the reactor. It is noted that the conversion rate recorded over 99% without oxidant when 800% of NaOH was pre-dosed into the reactor. In addition, under the addition of H₂O₂ as an oxidant, the increased amount of NaOH led to the improvement of conversion rate. The pre-dosed NaOH may contribute to the conversion rate of 2,4-DCP in the SCWO. However, due to low solubility of salt in the SCWO, the fouling problem should be solved in the SCWO process.     

氧化剂对硫化砷渣稳定化固化影响的初步研究

通过氧化剂种类及添加量的对比,探究了氧化剂对硫化砷渣稳定化固化的影响。确定了硫化砷渣稳定化固化的最佳氧化剂及添加量。结果表明：采用30%过氧化氢作为氧化剂对硫化砷渣进行氧化处理,处理效果最好,重金属浸出质量浓度可达到安全填埋《危险废物填埋污染物控制标准》(GB18598-2019)中的要求。在过氧化氢作为氧化剂,添加量25%,稳定化固化反应时间2 h,养护48 h的条件下,硫化砷渣稳定化固化效果最佳,砷的浸出质量浓度为0.003 mg/L。