碳酸盐缓冲体系中HS-电化学氧化机理及动力学性质  

Electrochemical oxidation mechanism and kinetic properties of HS-in carbonate buffer system

作　　者：薛敏华[1] 张震[1] 钱福军 莫友彬 曹家兴[1] XUE Min-hua1, ZHANG-zhen1 , QIAN Fu-jun1, MO You-bin2, CAO Jia-xing1(1. College of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China ;Guangxi Research Institute of Chemical Industry, Nanning 530001, China)

机构地区：[1]广西大学化学化工学院,广西南宁530004 [2]广西化工研究院,广西南宁530001

出　　处：《天然气化工—C1化学与化工》2018年第5期56-62,共7页Natural Gas Chemical Industry

基　　金：国家自然科学基金(21266003);广西教育厅自然科学基金(项目批准号201106LX026项目编号20110733)

摘　　要：采用电化学方法,考察HS^-在铂片电极上的循环伏安特性,并以循环伏安法、计时电量法、计时电流法测定其电极过程的动力学参数。结果表明:在Na2_CO_3-Na HCO_3缓冲溶液中,HS^-的循环伏安曲线在-0.05V电位值处有一个氧化峰,无还原峰;其氧化峰电流值I_p与扫描速率的开方(v^(1/2))呈线性关系(R=0.989),表明HS^-在电极上的氧化反应为受扩散控制的不可逆过程;初步推断其电极反应得失电子数为1、质子不参与反应,电极反应产物为S_2^(2-),S_2^(2-)可能进一步氧化产生S_4^(2-)。在20～60℃范围内,其HS^-的扩散系数D值随温度升高由1.33×10^(-6)cm^2/s增大至7.20×10^(-6)cm^2/s,HS^-的反应速率常数kf值由6.99×10^(-3)s^(-1)增大至1.70×10^(-2)s^(-1),当脱硫工艺温度为40℃时,其相应D值为3.07×10^(-6)cm^2/s、k_f值为1.09×10^(-2)s^(-1),反应级数为0.257;HS^-在电极上电化学氧化的平均活化能E_η=17.3kJ/mol。Electrochemical method was used to investigate the cyclic voltammetric behavior of HS^-on platinum electrode. And the kinetic parameters of the electrode process were measured by cyclic voltammetry, chronoamperometry and chronoamperometry.The results show that in the Na2 CO3-NaHCO3 buffer solution, the cyclic voltammogram of HS^-has an oxidation peak at the potential of -0.05 V and no reduction peak, and the oxidation peak current value Ipis linear with the square root of the scan rate（v^（1/2））（R=0.989）, which indicates that the oxidation of HS^-on the electrode is an irreversible process controlled by diffusion. It is preliminarily inferred that the number of transferred electrons in the electrode reaction is 1, protons do not participate in the reaction, and the electrode reaction product is S2^（2-）, which may be further oxidized to produce S4^（2-）. In the range of 20 to 60℃, the diffusion coefficient D value of HS^-increases from 1.33 ×10^（-6） cm^2/s to 7.20 ×10^（-6） cm^2/swith increasing temperature,and the reaction rate constant kfof HSincreases from 6.99×10^（-3） s^（-1） to 1.70×10^（-2） s^（-1） with increasing temperature.When the temperature of desulfurization process is 40℃, the values of D,kfand reaction order are 3.07 ×10^（-6） cm^2/s, 1.09 ×10^（-2） s^（-1） and 0.257, respectively.The average activation energy of the electrochemical oxidation of HS^-on the electrode（Eη） is 17.3 kJ/mol.

关 键 词：硫化物 多硫化物 循环伏安法 计时电量法 计时电流法 电化学动力学 

分 类 号：TQ546.5[化学工程—煤化学工程] O646.542[理学—物理化学]