Fe(Ⅲ)-EDTA吸收H2S反应动力学的实验研究

本文采用双搅拌无梯度气液反应器实验研究了Fe(III)-EDTA吸收H2S的反应动力学.建立并求解了H2S吸收数学模型 ,实验确定 Fe(III)-EDTA吸收H2S的化学反应速度常数为     

Fe(Ⅲ)-EDTA吸收羰基硫动力学研究

<正>在合成氨原料气中,羰基硫(COS)占有机硫的80%左右,天然气中COS亦高达500ppm,为了经济有效地脱除COS,作者经过筛选实验发现乙二胺四乙酸络合铁(Fe(Ⅲ)-EDTA)可以脱除COS,故对Fe(Ⅲ)-EDTA吸收COS的动力学进行了研究,揭示了该过程的控制步骤,建立了其数学模型,并提出了对该方法进行改进的可行性方案.     

Fe（Ⅱ）-EDTA/K2S2O8降解苯酚及反应动力学分析

考察了Fe(Ⅱ)-EDTA/K2S2O8体系降解苯酚的影响因素,并对体系中苯酚的降解机理和反应动力学进行了初步分析。结果表明,铁离子、氧化剂形态以及紫外光辐照、螯合剂的存在对氧化体系作用效果影响显著。EDTA剂量为0.5 mmol/L、Fe(Ⅱ)剂量为1.0 mmol/L、K2S2O8剂量为2.0 mmol/L、溶液初始pH值为7.0、温度为60℃的条件下反应60 min,浓度为100 mg/L的苯酚降解率为71.48%,同样条件下紫外光辐照时降解率可达89.38%。降解机理与动力学分析表明,苯酚在Fe(Ⅱ)-EDTA/K2S2O8体系中降解途径以与Fe4+络合降解为主。     

Mechanism and kinetics analysis of the phenol degradation by Fe(Ⅱ)-EDTA/K2S2O8 process

考察了Fe(Ⅱ)-EDTA/K2S2O8体系降解苯酚的影响因素,并对体系中苯酚的降解机理和反应动力学进行了初步分析。结果表明,铁离子、氧化剂形态以及紫外光辐照、螯合剂的存在对氧化体系作用效果影响显著。EDTA剂量为0.5 mmol/L、Fe(Ⅱ)剂量为1.0 mmol/L、K2S2O8剂量为2.0 mmol/L、溶液初始pH值为7.0、温度为60 ℃的条件下反应60 min,浓度为100 mg/L的苯酚降解率为71.48%,同样条件下紫外光辐照时降解率可达89.38%。降解机理与动力学分析表明,苯酚在Fe(Ⅱ)-EDTA/K2S2O8体系中降解途径以与Fe4+络合降解为主。     

三乙烯四胺合钴溶液脱除烟气中NO的实验研究

采用三乙烯四胺合钴溶液作为吸收液,在填料塔内,对模拟烟气进行了湿法脱硝的实验研究.主要考察了不同吸收液的NO脱除能力,以及温度和氧体积分数对NO脱除效率的影响.研究结果表明:无氧条件下,三乙烯四胺合钴溶液脱除NO的能力比Fe2+-乙二胺四乙酸(EDTA)溶液脱除NO的能力强;气相中的氧体积分数对NO的脱除影响显著,气相...     

NO与Co(NH_3)_6~(2+)气液反应动力学

用Co(NH3 ) 2 + 6的氨水溶液可同时实现NO的氧化和吸收过程 .NO与Co(NH3 ) 2 + 6气液反应动力学研究表明 ,NO与Co(NH3 ) 2 + 6的反应为瞬间反应 ,当Co(NH3 ) 2 + 6浓度低于 2 0mmol·L-1时过程为双膜控制 ,当Co(NH3 ) 2 + 6浓度大于 2 0mmol·L-1时过程逐渐变为气膜控制 .NO的吸收速度随温度的升高而降低 ,气相中氧的存在有利于NO的吸收 ,但当氧的含量高于 5 2 %后再继续增加氧的含量NO吸收速率提高不大 .经研究建立了有氧时NO与Co(NH3 ) 2 + 6气液反应动力学方程     

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％.     

曝气循环Fe~(3+)/UV光催化降解酸性橙Ⅱ

研究了曝气作用下Fe3+的UV光催化体系(Fe3+/UV/O2)对染料酸性橙Ⅱ的降解效果。试验结果表明,在该体系中染料的降解主要通过Fe3+光解反应产生.OH来完成。此外,曝气导致了Fe2+的光氧化并实现了降解反应的持续进行。在紫外灯功率为15 W、Fe3+的投加量为10 mg/L的条件下,经过180 min的反应,初始质量浓度为100 mg/L的酸性橙Ⅱ溶液能够完全降解。进一步的动力学分析表明酸性橙Ⅱ的降解符合一级反应动力学模型。     

亚硝酰亚铁螯合物(Ⅲ)Fe~Ⅱ(EDTMP)(NO)与亚硫酸钠的反应动力学研究

本文用快速混合法研究了水溶液中乙二胺四甲叉膦酸根亚硝酰铁(Ⅱ)与亚硫酸钠之间的反应动力学.在pH=5.88和离子强度0.3mol/1的条件下,上述反应为二级反应.测得20,25,30和35℃时的反应速率常数k分别为1.95,3.03,5.48和7.05 1/mol·min,表观反应活化能为68.6kJ/mol,比FeⅡ(EDTA)(NO)体系的活化能要小.讨论了溶液酸度对k的影响.     

NO与Co(NH3)2+6气液反应动力学

用Co(NH₃)²⁺₆的氨水溶液可同时实现NO的氧化和吸收过程.NO 与Co(NH₃)²⁺₆气液反应动力学研究表明,NO与Co(NH₃)²⁺₆的反应为瞬间反应,当Co(NH₃)²⁺₆浓度低于20mmol&#8226;L^-1时过程为双膜控制,当Co(NH₃)²⁺₆浓度大于20mmol&#8226;L^-1时过程逐渐变为气膜控制.NO的吸收速度随温度的升高而降低,气相中氧的存在有利于NO的吸收,但当氧的含量高于5.2%后再继续增加氧的含量NO吸收速率提高不大.经研究建立了有氧时NO 与Co(NH₃)²⁺₆气液反应动力学方程.     

Removal of nitric oxide and sulfur dioxide from flue gases using a FeII-ethylenediamineteraacetate solution

The combined absorption of NO and SO₂ into the Fe(II)-ethylenediamineteraacetate(EDTA) solution has been realized. Activated carbon is used to catalyze the reduction of Fe^III-EDTA to Fe^II-EDTA to maintain the ability to remove NO with the Fe-EDTA solution. The reductant is the sulfite/bisulfite ions produced by SO₂ dissolved into the aqueous solution. Experiments have been performed to determine the effects of activated carbon of coconut shell, pH value, temperature of absorption and regeneration, O₂ partial pressure, sulfite/bisulfite and chloride concentration on the combined elimination of NO and SO₂ with Fe^II-EDTA solution coupled with the Fe^II-EDTA regeneration catalyzed by activated carbon. The experimental results indicate that NO removal efficiency increases with activated carbon mass. There is an optimum pH of 7.5 for this process. The NO removal efficiency increases with the liquid flow rate but it is not necessary to increase the liquid flow rate beyond 25 ml min^?1. The NO removal efficiency decreases with the absorption temperature as the temperature is over 35 °C. The Fe²⁺ regeneration rate may be speeded up with temperature. The NO removal efficiency decreases with O₂ partial pressure in the gas streams. The NO removal efficiency is enhanced with the sulfite/bisulfite concentration. Chloride does not affect the NO removal. Ca(OH)₂ and MgO slurries have little influence on NO removal. High NO and SO₂ removal efficiencies can be maintained at a high level for a long period of time with this heterogeneous catalytic process.     

Absorption of nitrogen monoxide in aqueous solutions containing sulfite and transition-metal chelates such as Fe (II)-EDTA,Fe (II)-NTA,Co (II)-Trien and Co (II)-Treten

For wet denitrification processes nitrogen monoxide is the crucial component owing to its low water solubility. By addition of transition-metal complexes, able to form nitrosyls, the effective NO concentration in the liquid phase is enhanced. Kinetic (reaction orders and rate constants) as well as thermodynamic (stability constants) data for nitrosylation have been established. It has been found that Fe(II)-EDTA and Fe(II)-NTA react very fast to form stable NO complexes and are widely pH independent. The formation of Fe(III)-EDTA nitrosyl is found to be rapid, but the large deviation in the measured data prevents reliable evaluation. While the equilibrium constants of the Co(II)-trien and Co(II)-tetren nitrosyls are largely pH independent, the rate of formation is influenced markedly by pH. Each nitrosyl shows individual behavior towards sulfite. Fe(II)-EDTA and Fe(III)-EDTA exhibit the highest absorption capacities. The CO(II) polyamines convert the absorbed NO mainly to gaseous N₂O rather than to liquid-phase products.     

Reduction of Fe(II)EDTA‐NO using Paracoccus denitrificans and changes of Fe(II)EDTA in the system

BACKGROUND: In the BioDeNO_X technology for NO_X removal from flue gas, bioreduction of Fe(II)EDTA‐NO and Fe(III)EDTA are core processes. In this study, a newly isolated strain, Paracoccus denitrificans, was used to reduce Fe(II)EDTA‐NO with glucose and Fe(II)EDTA as donor electrons. To better understand the change law of Fe(II)EDTA, the process of Fe(II)EDTA‐NO reduction by P. denitrificans with glucose and Fe(II)EDTA as electron donors was investigated, and the factors that might affect Fe(II)EDTA concentration were studied. RESULTS: For the bioreduction process of Fe(II)EDTA‐NO, P. denitrificans could use glucose and Fe(II)EDTA as electron donors. At different stages, primary electron donors were different, thereby affecting the concentration of Fe(II)EDTA in the system. It was also proved that this strain not only reduced Fe(III)EDTA with glucose as the electron donor but also secreted several substances that reacted with Fe(III)EDTA, resulting in increased Fe(II)EDTA concentration in the solution. CONCLUSIONS: This work has shown that P. denitrificans can reduce Fe(II)EDTA‐NO and Fe(III)EDTA simultaneously to regenerate NO_X absorption solution. © 2012 Society of Chemical Industry     

Nitrosymmetallochelates—I. Mechanism of FeNO—EDTA complex formation and its oxidation

A nitrosyliron(II) complex with EDTA was produced by reaction of the Fe(II)—EDTA complex and nitrous acid in citric acid—phosphate buffer solution. The experimental results pointed out that nitrous acid is reduced to nitrous oxide by Fe(II)—EDTA complex followed by the formation reaction of nitrosyliron(II) EDTA complex. The composition of this complex was determined to be Fe(II) (NO)₂EDTA by both electrochemical and spectroscopic methods.A mechanism of the oxidation of Fe(II) (NO)₂EDTA was proposed in which nitrous oxide breaks away from the iron ion. The photoeffect on this reaction is discussed.     

Metal chelate absorption coupled with microbial reduction for the removal of NOx from flue gas

A novel process for the removal of NO_x from flue gas by a combined Fe(II)EDTA absorption and microbial reduction has been demonstrated. Fe(II)EDTA–NO and Fe(III)EDTA (EDTA: ethylenediaminetetraacetate) can be effectively reduced to the active Fe(II)EDTA in the reactor containing microorganisms. In a steady‐state absorption and regeneration process, the final removal efficiency of NO is up to 88%. The effects of four main parameters (i.e. NO, O₂ and SO₂ concentrations, and the amount of cyclic solution) on NO_x removal efficiency were experimentally investigated at 50 °C. The results provide some insight into conditions required for the successful removal of NO_x from flue gas using the approach of Fe(II)EDTA absorption combined with microbial reduction. Copyright © 2005 Society of Chemical Industry     

An indirect electrochemical process for the removal of NOx from industrial waste gases

The development of a new electrochemical process for the absorption of NOx from industrial waste gases is described. Conversion of NO was performed by an indirect outer cell process using dithionite as the redox mediator and Fe(II)EDTA as the complexing agent. The absorption process, involving complex formation with Fe(II)EDTA in the absence and presence of dithionite, was investigated using a packed bubble column. In semibatch experiments the dependence of different system parameters on the degree of NO conversion was studied: concentration of dithionite and Fe(II)EDTA, gas flow rate, oxygen content, and temperature. The reaction products in the gas phase and in the liquid phase were analyzed using gas chromatography and ion chromatography, respectively. This analysis proved that, instead of N2 or N2O, ammonia and amidosulfonic acid are the main reaction products in the solution. The kinetics and the conditions for the regeneration of dithionite by electrochemical reduction of sulfite were studied on RDE and by experiments in a divided cell. For the dithionite production a current efficiency of about 80% was found in 0.2 m Na2SO4 at pH 5.6. By combining the chemical NO absorption in a gas/liquid contactor with the electrochemical regeneration of dithionite in a divided plate and frame cell a degree of NO conversion better than 90% under continuous operation can be obtained.     

Denitrification in aqueous FeEDTA solutions

The biological reduction of nitric oxide (NO) in aqueous solutions of FeEDTA is an important key reaction within the BioDeNOx process, a combined physico‐chemical and biological technique for the removal of NO_x from industrial flue gasses. To explore the reduction of nitrogen oxide analogues, this study investigated the full denitrification pathway in aqueous FeEDTA solutions, ie the reduction of NO₃^?, NO₂^?, NO via N₂O to N₂ in this unusual medium. This was done in batch experiments at 30 °C with 25 mmol dm^?3 FeEDTA solutions (pH 7.2 ± 0.2). Also Ca²⁺ (2 and 10 mmol dm^?3) and Mg²⁺ (2 mmol dm^?3) were added in excess to prevent free, uncomplexed EDTA. Nitrate reduction in aqueous solutions of Fe(III)EDTA is accompanied by the biological reduction of Fe(III) to Fe(II), for which ethanol, methanol and also acetate are suitable electron donors. Fe(II)EDTA can serve as electron donor for the biological reduction of nitrate to nitrite, with the concomitant oxidation of Fe(II)EDTA to Fe(III)EDTA. Moreover, Fe(II)EDTA can also serve as electron donor for the chemical reduction of nitrite to NO, with the concomitant formation of the nitrosyl‐complex Fe(II)EDTA–NO. The reduction of NO in Fe(II)EDTA was found to be catalysed biologically and occurred about three times faster at 55 °C than NO reduction at 30 °C. This study showed that the nitrogen and iron cycles are strongly coupled and that FeEDTA has an electron‐mediating role during the subsequent reduction of nitrate, nitrite, nitric oxide and nitrous oxide to dinitrogen gas. Copyright © 2004 Society of Chemical Industry