核黄素丁酸酯在汞电极上的吸附伏安特性及其反应速率常数的测定

Adsorptive Voltammetric Behavior of Riboflavine Tetrabutyrate and Its Measurement of Rate Constant at the Mercury Electrode

循环伏安法表明，在ＮａＯＨ底液中核黄素丁酸酯（ｒｉｂｏｆｌａｖｉｎｅ ｔｅｔｒａｂｕｔｙｒａｔｅ，ＲＴ）在汞电极上有一对氧化还原峰，其峰电位Ｅｐｃ＝Ｅｐａ＝－０．６４Ｖ（ｖｓ．Ａｇ／ＡｇＣｌ）。本文用多种电化学手段对ＲＴ的吸附特性进行了较详细的研究。吸附粒子为ＲＴ中性分子，测得ＲＴ在汞电极上的饱和吸附量为５．４２×１０－１１ｍｏｌ／ｃｍ２，每个ＲＴ分子所占电极面积为３．０６ｎｍ２，ＲＴ在悬汞电极上的吸附符合Ｆｒｕｍｋｉｎ等温式。测得吸附系数β＝４．６×１０５，吸引因素γ＝ １． １０，吸附自由能△Ｇ°＝－ ３２． ３０ ｋＪ／ｍｏｌ。本文还用循环伏安法研究了ＲＴ的电极反应动力学性质，测定了其在汞电极上的反应速率常数。

Cyclic voltammetry shows that, in a supporting electrolyte of NaOH, riboflavine tetrabutyrate (RT) has a pair of cathodic and anodic peaks at Hg electrode. The peak potentials E-pc = E-pa = - 0.64 V(vs. Ag/Agcl). The adsorptive characteristics of RT are explored in details with various methods. The adsorbed species is most probably neutral molecule of RT. The saturated adsorption amount of RT at Hg electrode is 5.42 x 10(-11) mol/cm(2) and every RT molecule occupied 3.06 nm(2). On the surface of HMDE, the adsorption of RT obeys Frumkin dasorption isotherm. The adsorptive coefficient beta, the attractive factor gamma are 4.60 x 10(5), 1.10 and the adsorption free energy DeltaG ', is - 32.30 kJ/mol, respectively. The electrode process kinetic behavior has also been studied by using cyclic voltammetry. Under the experimental conditions the rate constants for electron transfer are determined. The values of k(s) are in good agreement with literature's results.