臭氧在对硝基苯酚溶液中的吸收与模拟过程

研究了鼓泡塔中臭氧在对硝基苯酚溶液中的吸收传质过程。首先探讨了pH值和气速对对硝基苯酚降解速率的影响。在 298K下,臭氧被连续通入对硝基苯酚溶液中,臭氧的传质速率因为溶解臭氧与对硝基苯酚的快速反应而大大加强。然后运用与实验条件相同的操作参数,进行了臭氧在鼓泡塔中吸收过程的模拟研究,采用MATLAB软件求解吸收过程的质量平衡方程,模拟了吸收过程中臭氧和对硝基苯酚浓度的变化,并与实验值进行了比较。结果表明,在短的鼓泡塔中,应用全混流模型来描述气相和液相的流体状态是可行的,在 80%的对硝基苯酚降解之前,模拟值和实验值能很好地一致。     

Kinetics of the absorption of carbon dioxide into aqueous ammonia solutions

Experiments were performed in a customized double stirred tank reactor to study the kinetics of CO₂ absorption into NH₃ solutions at concentrations ranging from 0.42 to 7.67 kmol·m^?3 and temperatures between 273.15 and 293.15 K. The results show that the reactive absorption was first order with respect to CO₂ but fractional order (1.6–1.8) with respect to ammonia. Experimental data can be satisfactorily interpreted by a termolecular mechanism using and . © 2016 American Institute of Chemical Engineers AIChE J, 62: 3673–3684, 2016     

Mass transfer and selectivity of ozone reactions

The present research concerns the behavior of mass transport in absorption of ozone accompanied by decomposition and ozonation reactions in aqueous solutions. On the basis of the film theory, a mathematical model has been formulated for the transport process taking into account molecular diffusion and the simultaneous decomposition and ozonation reactions of different orders. Analytical approximate and finite difference methods have been employed to predict concentration profiles, enhancement factor and selectivity of the chemical mass transfer in gas-liquid systems. The rate of mass transfer is enhanced by the chemical reactions as well as the availability of liquid reactant in the aqueous phase. When the ozonation reaction is much faster than the decomposition reaction, a large fraction of the absorbed ozone is utilized effectively in reacting with the liquid constituent and a high selectivity of the gas-liquid reactions can be obtained. Calculated results indicate that removal of certain organic pollutants by the oxidation process may be effective only in acidic or neutral solutions where a high mass transfer rate and selectivity is achieved.     

吸收过程的界面传质机理

Based on the method of molecular thermodynamics ,the mass transfer mechanism at gas-liquid interface is studied theoretically,and a nowe mathematical model is proposed,Using laser holographic interference technique,the hydrodynamics and mass transfer characteristics of CO2 absorption are measured,It is shown that the calculated results are in good agreement with the experimental data.     

Absorption of carbon monoxide with reversible reaction in cualcl4-toluene-complex solutions

The absorption of CO in CuAlCl₄-toluene-complex solutions was studied in a stirred reactor. The reaction was found to occur in a fast reaction regime. The effect of CO partial pressure, CuAlCl₄-toluene-complex concentration and temperature on the rate of absorption was studied. The results have been interpreted using a theoretical model for mass transfer with reversible chemical reaction and the rate parameters were determined. The equilibrium constants were also determined experimentally. An interesting observation showing a decrease in the rate with an increase in temperature was made for this system. This is explained on the basis of a higher activation energy for the reverse reaction. The activation energies evaluated for the forward and reverse reactions are 32.93 and 97.42 kJ/mol, respectively.     

Ozonation kinetics of iron and manganese in aqueous solution

Ozonation kinetics of iron and manganese in aqueous solution is experimentally investigated. The effects of pH, initial ion concentration and the ozone dosage on the kinetic rate parameters are examined. It has been found that ozonation of those ions in general follows zero order kinetics.     

活性炭/水浆料中CO2吸收过程的增强

针对分散相微粒增强难溶气体的吸收过程,提出了一个一维非稳态非均相传质的二区模型,并进行了理论求解。根据表面更新理论,得到了增强因子的数学表达式。利用恒温反应釜,对活性炭/水浆料中发生的CO2吸收过程进行了实验研究,测定了不同颗粒浓度及转速下的增强因子。实验结果与模型预测值吻合良好,表明本文模型具有很高的预测精度。     

Kinetics of CO2 absorption by aqueous 3‐(methylamino)propylamine solutions: Experimental results and modeling

Experimental data and a model for the initial kinetics of CO₂ into 3‐(methylamino)propylamine (MAPA) solutions are presented in work. MAPA has been tested as an activator for tertiary amines with encouraging results. The measurements were performed in a string of discs contactor and, as no initial kinetics data are available in literature, additional measurements were carried out and in a wetted wall column. The obtained overall mass‐transfer coefficients from both apparatuses are in reasonable agreement. To obtain values for the observed kinetic constant, , the experimental results were interpreted using a two‐film mass‐transfer model and invoking the pseudo‐first order assumption. Needed experimental values for density, viscosity, and Henry's law coefficient for CO₂ were measured and are given. The results indicate that MAPA is almost twice as fast as piperazine, eight times faster than 2‐(2‐aminoethyl‐amino)ethanol (AEEA), and 15 times faster than monoethanolamine, when comparing unloaded 1 M solutions at 25°C. The observed kinetic constant was modeled using the direct mechanism. The final expression for can be applied for any concentration and temperature within the experimental data range, and, together with the presented physical data, comprises a complete model for calculating absorption fluxes. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3792–3803, 2014     

多孔电极臭氧发生器氧化废水中有机物的吸收和反应动力学分析(英文)

A novel electrode design for the in situ generation of ozone in the reaction zone of a tubular reactor is described in this work.The ozone generator uses a porous inner electrode tube in the corona discharge assembly,and the ozone generated around the outer periphery of the porous tube diffuses into the tubular reactor and reacts with the contaminants in the fluid that is being treated.A mathematical model that includes absorption and second order reaction in the film is developed to describe ozonation kinetics of a contaminant dye in the tubular reactor.The model describes the experimental data for dye decolorization,oxidation byproducts,dissolved ozone,and ozone gas concentrations well.Model analysis indicates that the fast dye decolorization reaction occurs partly in the liquid film and partly in the bulk fluid.The model can be used in the selection of appropriate gas-liquid contactors for efficient oxidation of contaminants in effluents.     

吸收过程的界面非平衡传质机理

针对气体吸收过程,以分子热力学为基础,结合普遍化的化学势推动力通量方程,导出了传质存在时两相界面处的浓度关系,并针对不同情况进行了求解.提出了一个反映液相侧动力学状况的无因次数群Biot数Yo,Yo数越大界面处两相越偏离平衡.界面浓度是与Yo和液相主体浓度密切相关的.对于气相阻力可以忽略的吸收过程,两相传质速率的大小主要取决于液相的溶质界面浓度和液膜厚度.采用激光显微全息干涉技术对甲醇,乙醇,正丙醇静止吸收CO2时的界面浓度进行了测定,试验结果表明了本研究模型的正确性.     

Kinetics of oxygen absorption in aqueous sodium dithionite solutions

The absorption and reaction of oxygen in aqueous alkaline solutions of sodium dithionite has been experimentally investigated in a novel gas-liquid contactor. The novel gas-lift bubble column contactor was used to study the kinetics over wide ranges of reactant concentrations, temperature, and pH. The oxygen-sodium dithionite reaction was found to be first-order with respect to dithionite in the range of dithionite concentration < 0.1 M, and second-order in the range of dithionite concentration > 0.1 M. The reaction with respect to oxygen was found to be zero-order for all dithionite concentrations. These results and experimental investigations of the effect of solution alkalinity and temperature on the reaction rate are consistent with previous findings obtained in different gas-liquid contactors. The results thus confirm the feasibility of using the gas-lift bubble column for the kinetics of gas-liquid reactions.     

臭氧降解水中邻苯二甲酸二甲酯的效能及动力学

利用臭氧降解含较高浓度邻苯二甲酸二甲酯(DMP)的模拟废水,考察了pH、DMP初始浓度、臭氧投加量和温度对臭氧降解DMP效果的影响,并对臭氧降解DMP的效能及动力学进行了研究。结果表明,pH为5～10时DMP的降解效果较好;DMP初始浓度越大,DMP降解率越小,但DMP降解量增加;臭氧投加量的增加有利于DMP降解,但臭氧利用效率降低;温度低时,升高温度DMP降解率增大,24℃后提高温度对DMP降解率影响不大。在pH为5～10、DMP初始浓度为14～66 mg·L^-1、O₃投加量为14～24 mg·min^-1、20～30℃条件下反应40 min,DMP降解率达85%以上。在实验条件范围内,臭氧降解DMP符合拟一级动力学,建立了幂指数表达的动力学模型。在pH为2～12范围内,因臭氧反应机理不同,表观动力学常数k_obs与pH不呈线性关系,pH为2～5时,k_obs快速增加,pH为5～9时,k_obs缓慢增加,pH大于9时k_obs反而降低,pH为9时k_obs最大,为0.0929 min^-1。     

Ozonation of chloronitrobenzenes in aqueous solution: kinetics and mechanism

BACKGROUND: Chloronitrobenzenes (ClNBs) are a family of toxic and bio‐resistant organic compounds. Ozone treatment is specifically suitable for partial or complete oxidation of non‐biodegradable components. However, few studies on the decomposition of ClNBs by ozone are available, and kinetics and mechanisms of ClNBs ozonation have not been thoroughly investigated. The kinetics and mechanism of ozonation degradation of ClNBs in aqueous solution were investigated, and the contribution of both molecular ozone and hydroxyl radicals was also evaluated. RESULTS: The results demonstrated that the decomposition of ClNBs was a pseudo‐first‐order reaction with respect to the pollutant concentration and the overall rate constant increased with an increase in pH. It declined, however, with an increase in pollutant and radical scavenger concentration. Furthermore, TOC removal rate was significantly lower than that of ClNBs, but the same order o‐ClNB < m‐ClNB < p‐ClNB was followed. Ozonation could not reduce TOC significantly, p‐chlorophenol, p‐nitrophenol, 2‐chloro‐5‐nitrophenol and 5‐chloro‐2‐nitrophenol were detected as primary degradation intermediates in ozonation of p‐ClNB. Rate constants of the direct reaction between ozone and ClNBs at 25 °C had been found to be lower than 1 M^?1S^?1. More than 95% of ClNBs removal was due to hydroxyl radical oxidation at pH ≥ 7. CONCLUSION: Advanced oxidation processes may be the preferred choice for the elimination of ClNBs from the environment. Copyright © 2008 Society of Chemical Industry     

臭氧化去除水中对硝基氯苯动力学及机理

引言 对硝基氯苯(pCNB)广泛应用于农药、染料、医药、防腐剂等工业领域.随着工业废水的排放,我国一些主要水体中均有pCNB的检出[1-2].     

Kinetics of carbon dioxide chemical absorption into cyclic amines solutions

Chemical reaction kinetics between carbon dioxide with two cyclic amines (pyrrolidine and piperidine) have been studied using a stirred tank reactor with a planar interfacial area. The operational variables considered in this work have been the amine concentration in the liquid phase and the reaction temperature. Specific absorption rates have been determined under different experimental conditions. Results indicate that the absorption process occurs in a pseudo first reaction regime exhibited first‐order kinetic with respect carbon dioxide and a second order for both cyclic amines. The reaction‐rate constant was determined under the different experimental conditions, and it was correlated depending on the temperature by means of an Arrhenius type equation. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

微通道内醇胺/离子液体复配水溶液吸收CO2的传质特性

研究了微通道内醇胺[单乙醇胺(MEA)和甲基二乙醇胺(MDEA)]与离子液体[1-丁基-3-甲基咪唑四氟硼酸([Bmim][BF₄])和1-羟乙基-3-甲基咪唑甘氨酸([C₂OHmim][GLY])]复配水溶液吸收CO₂的传质特性。考察了醇胺/离子液体浓度比(c_AA∶c_IL)对液相体积传质系数(k_La)的影响,发现k_La随反应速率的增大而增大。为进一步阐释复配水溶液吸收CO₂的传质机理,分析了比表面积、扩散速率、增强因子和液弹循环对传质速率的影响。结果表明,四种复配溶液中,反应速率和循环频率(f_cir)分别在低流率和高流率下对传质速率起主导作用。k_La可表示为f_cir的函数,低气相流率下k_La与f_cir呈线性关系,斜率与反应速率成正相关,高气相流率下,液弹循环因膜弹传递困难而对整体传质速率的影响减弱,k_La与f_cir呈指数关系,幂律指数小于1。     

双搅拌釜中半胱氨酸亚铁溶液吸收NO的传质-反应动力学

以半胱氨酸亚铁络合物Fe(Ⅱ)(CyS)₂作为吸收剂,在双搅拌釜内探讨了NO吸收反应动力学.实验结果表明：在pH=8.0,T=323 K实验条件下,半胱氨酸亚铁溶液吸收NO气体为快速拟一级反应,得到二级反应速率常数k₂=1.18×10⁵ m³&#8226;mol^-1&#8226;s^-1.3种理论模型即膜模型、Danckwerts表面更新模型、Higbie渗透模型应用于该拟一级反应,增强因子的计算结果是相同的.实验获得的增强因子与模型计算值吻合较好,最大相对偏差不超过13％.     

The pH dependence of the ozone absorption kinetics in aqueous phenol solutions

Using a wetted wall laboratory absorber, the rate of ozone absorption in aqueous phenol solutions has been measured in the pH range 1.75–12.The phenol concentration was varied in a wide range (7–800 ppM) and the ozone partial pressure over a six-fold range. The temperature and the liquidThe results were interpreted by assuming that the rate determining step of a reaction sequence is different in acid and basic solutions.     

T型微通道内吸收H2S实验研究

在水力学直径为1.00 mm的方形T型微通道内,采用质量分数为40%的N-甲基二乙醇胺(MDEA)吸收含有体积分数为0.12%的H2S混合气体。实验发现,在微通道内可以获得很高的H2S脱除效率,在气液体积比为200∶1时,其脱除效率可以达到99.5%。在微通道内的H2S传质过程中,H2S传质的阻力主要集中在气侧,而且气侧体积传质系数随着气体和液体表观速率的增加而增加。提出了在过渡区的二相流型中,气侧体积传质系数的量纲一经验关联式,其计算值和实验值吻合得很好。通过比较发现,微通道比其他传统设备的气侧体积传质系数高出1—2个数量级。