Precipitate formation during sea water electrolysis

A small experimental cell was used to study factors affecting the cathodic fouling of nickel electrodes during the electrolysis of recirculated synthetic sea water. The electrolyte concentration ranged from 12 to 3 times that of normal sea water. Flow rate and current density were varied to determine the effects on both bulk and surface precipitate formation. The effect of electrolyte concentration on the amount of precipitation was predicted using a mass transfer approach for fixed flow rates. Increasing current density did not affect total precipitate formation but did reduce surface precipitate formation for the more concentrated solutions. High fluid flow rate was effective in reducing total precipitate formation and, to some extent, adhered precipitate formation but the amount was not readily predictable, although it apparently decreased linearly with increasing flow rate. The initiation of the adhered precipitate formation did not take place randomly but began at specific surface sites and spread with growth rate depending on surface potential.