Fe^ⅡEDTA络合-Na2SO3还原吸收NO性能

Experimental Study on Complexing Absorption of NO Using Fe^ⅡEDTA Solution and Reduction with Na_2SO_3 Solution

为研究Fe^ⅡEDTA络合-Na2SO3还原吸收NO性能,对制备参数〔pH、V（Fe^ⅡEDTA）（Fe^ⅡEDTA溶液用量）、初始c（Fe^ⅡEDTA）、n（Fe^Ⅱ）∶n（EDTA）〕和操作条件〔温度、φ（O2）、烟气流量、入口ρ（NO）〕及SO32-〔以c（Na2SO3）计〕进行了考察,并采用FT-IR（傅里叶红外光谱仪）和Raman（拉曼光谱仪）等表征手段对吸收体系进行表征.结果表明：1pH和初始c（Fe^ⅡEDTA）对NO络合吸收量影响较显著,V（Fe^ⅡEDTA）和n（Fe^Ⅱ）∶n（EDTA）次之.在pH为3^9的范围内,NO络合吸收量先增加后降低,pH为7时达到最大（0.502 mol/mol）;初始c（Fe^ⅡEDTA）由0.005 mol/L增至0.025 mol/L,NO络合吸收量随之增加了0.198 mol/mol.2温度和φ（O2）的升高不利于NO吸收,当温度由30℃升至60℃、φ（O2）从0%增至6%,NO络合吸收量却分别降低了71.69%、63.3%;此外,烟气流量和入口ρ（NO）的增加对NO络合吸收量也无显著影响.3SO32-的存在显著提高了Fe^ⅡEDTA高效络合NO吸收时间.结合试验结果确定最佳反应条件：pH为7、V（Fe^ⅡEDTA）为550 m L、初始c（Fe^ⅡEDTA）为0.020 mol/L、n（Fe^Ⅱ）∶n（EDTA）为1∶1.0、温度为30℃、烟气流量为900 m L/min、无氧、c（Na2SO3）为0.20 mol/L,此时,NO络合吸收量为1.099 mol/mol,NO最大脱除率达到96.98%.研究显示,溶液中n（Fe^ⅡEDTA）∶n（NO）对络合吸收NO起到主导作用,同时SO32-对Fe^ⅡEDTA（NO）还原作用是促进NO吸收的重要机制.

In order to study the abilities of absorbing NO,Fe^ⅡEDTA complex coupled with Na2SO3 was used as reductant. The influences of the preparation parameters（ e. g.,pH value,volume of the Fe^ⅡEDTA solution,initial concentration of the Fe^ⅡEDTA solution and Fe^Ⅱ/EDTA molar ratio）,operation conditions（ e. g.,temperature,oxygen content,gas flow rate and NO concentration of the entrance）and the concentration of SO32-were investigated. FT-IR and Raman spectroscopy were used to characterize the absorption solution. The results showed that：（ 1） The pH value and the initial concentration of the Fe^ⅡEDTA solution significantly affected the complex absorption of NO,while the volume of the Fe^ⅡEDTA solution and the Fe^Ⅱ/EDTA molar ratio were less important. When the pH value of the solution was varied from 3 to 9,NO absorption increased at first and then decreased slightly,and the maximum absorption reached 0. 502 mol/mol when the pH value was 7. NO absorption increased by 0. 198 mol/mol when the initial concentration of the Fe^ⅡEDTA solution was increased from 0. 005 to 0. 025 mol/L.（ 2） A higher temperature and oxygen content were not favorable to the absorption of NO. NO absorption decreased by 71. 69% and 63. 3% when the temperature increased from 30 ℃ to 60 ℃ and the oxygen content increased from0% to 6%. The effects of the gas flow rate and the entrance NO concentration on absorption of NO were insignificant.（ 3） The existence of the SO32-component improved the capacity of absorbing NO.The optimal conditions of absorbing NO were determined as follows： pH was 7,volume of the Fe^ⅡEDTA solution was 550 m L,initial concentration of Fe^ⅡEDTA solution was 0. 020 mol/L,Fe^Ⅱ/EDTA molar ratio was 1∶ 1,temperature was 30 ℃,gas flow rate was 900 m L/min,concentration of O2 volume should be 0%,and concentration of the Na2SO3 solution was 0. 20 mol/L. NO absorption and the maximum removal efficiency were 1. 099 mol/mol and96. 98%,respectively. The research showed that the molar ratio of Fe^ⅡEDTA to NO had a crucial effect on absorbing NO. Meanwhile,the existence of SO32-could promote the reduction of the Fe^ⅡEDTA（ NO） and lead to better complex absorption of NO.