Effect of surfactants on the rate of mass transfer at gas-evolving electrodes

The effect of sodium lauryl sulphate surfactant on the mass transfer coefficient of the cathodic reduction of ferricyanide ion and the anode oxidation of ferrocyanide ion at hydrogen- and oxygen-evolving electrodes, respectively, was studied. Also, the effect of sodium lauryl sulphate on the gas hold-up and cell voltage was studied. The presence of surfactant in the electrolyte was found to decrease the mass transfer coefficient by an amount ranging from 7.6 to 81% depending on the operating conditions. Gas hold-up and cell voltage were found to increase in the presence of surfactant.Nomenclature C concentration - F Faraday constant (96 487 C mol^–1) - I_I limiting current under natural convection - I current consumed in ferricyanide reduction or ferrocyanide oxidation during electrolysis with gas evolution - K mass transfer coefficient - V gas discharge rate - Z number of electrons involved in the reaction - gas hold-up