Coulostatic Study of Residual Oxygen in Electro-Chemical Investigations

摘要

Residual oxygen concentrations of about 5 x 10 to the-7th power M were measured in nitrogen- and hydrogen-saturated buffer solutions by the coulostatic method using a hanging mercury drop electrode. Light pre-electrolysis of the buffer solutions was found to cause very little alteration of the measured values but under some conditions the apparent oxygen concentration became much smaller and other phenomena occurred. These phenomena were accentuated when the hydrogen used was strongly deoxygenated. In the region of the first oxygen wave a mass transfer-controlled oxidation was predominant, no oxygen reduction currents being observable, but at much more negative potentials a pseudocapacity was observed, a more or less stable rest potential (having a range of values) being attained in a few seconds almost regardless of the coulostatic charge applied. It is probable that a redox couple is responsible but the occurrence of similar phenomena in two different buffers makes an impurity effect less likely. An explanation in terms of the hydrogen molecule ion, produced in solution as the result of pre-electrolysis, is tentatively suggested. (Author)