β-苯胺基苯丙酮在铁电极上吸附动力学的研究

A Study of Adsorption Kinetics of β-phenylaminopropiophenone on Iron in Acid Solution

用计时电流法研究了０．５ｍｏｌ／ＬＨ２ＳＯ４溶液中β－苯胺基苯丙酮（ＰＡＰ）、卤素离子（Ｃｌ－，Ｉ－）在铁电极上的吸附动力学行为以及Ｃｌ－对ＰＡＰ吸、脱附速度的影响，求得了吸、脱附速度常数ｋａ、ｋｄ和吸附自由能参数ｆ值．结果表明，当ＰＡＰ发生化学吸附时，ｋａ比ｋｄ约大２个数量级，吸附粒子间存在吸引力．在电极表面已吸附有Ｃｌ－的条件下，且当ＰＡＰ浓度较低时发生静电吸附，ｋａ比ｋｄ约大４个数量级，吸附粒子间存在排斥力；浓度高时则发生化学吸附．

The adsorption kinetics of β-phenylaminopropiophenone (PAP) on iron electrode in 0.5 mol/L H_2SO_4 solution with or without Cl^- were investigated by chronoamperometry. According to the following adsorption kinetic equation dθ/dt=kaCen-1(1-θ)nexp(fθ/2)-kdθexp(-fθ/2)The rate constants ka, kd as well as the adsorption free energy parameter f of PAP in sulfuric acid soltuion was calculated by used a computerized curve fitting program, the calculated ka, kd are in the order of 10^-1 mol/L s~-1 and 10^-3 s-1, respectively, f>0 in the concentration region of 5×10^-5 to 1×10^-3 mol/L of PAP. While in the 0.5 mol/L H_2SO_4 solution with 0.1 mol/L Cl-,the values of ka, kd are 66 mol/L s^-1 and 1.8×10^-3 s-1, respectively, f<0 when CPAP=2×^-5 mol/L, but the ka, kd equal to 1.2×10^-2 mol/L s^-1, 4.9×10^-4 s^-1, and f>0 when CPAP=1×10^-3 mol/L. Otherwhere, authors proved that the PAP occurred electrostatic adsorption under former condition, and it is chemisorbed on the iron surface under latter condition.