Electrochemical investigation of contact angle and of flotation in the presence of alkylxanthates. I. Platinum and gold surfaces

Abstract

The contact angle between a nitrogen bubble and platinum or gold electrode surfaces immersed in xanthate solutions has been determined as a function of the quantity of dixanthogen on the metal surface for the methyl, ethyl and butyl compounds. Significant angles result from fractional coverages, but multilayers are required before the maximum angle, characteristic of the particular alkyldixanthogen, is reached. The quantity of dixanthogen required to float a particulate bed electrode of gold spheres was determined for a number of alkylxanthates. The required quantity varied from multilayers for methyl to low fractional coverages for the longer chain compounds. Nevertheless the static contact angle corresponding to these coverages was in each case found to be close to 55� for the three alkyldixanthogens studied. When butyl- or pentyl-xanthates were used at typical concentration levels applicable to practical situations (10 p.p.m.), flotation was inhibited when the quantity of dixanthogen formed was more than two to four times greater than the minimum amount necessary for flotation to occur. This inhibition arose from flocculation of the gold particles.