Ethyl xanthate chemisorption isotherms and Eh-pH diagrams for the silver + water + ethyl xanthate system

AFM force measurements between gold and silver surfaces treated in ethyl xanthate solutions: Effect of applied potentials

“…As shown, both the contact angle and the surface forces increase at potentials above À400 mV, indicating that the anodic current observed beginning at À350 mV is due to xanthate adsorption. This finding is consistent with the observation reported by Woods et al (1992Woods et al ( , 1994b) that chemisorption of ethyl xanthate begins at À350 mV. However, the FTIR spectra obtained by Woods et al (1992) did not show the presence of chemisorbed xanthate at potentials below À150 mV.…”

“…This finding is consistent with the observation reported by Woods et al (1992Woods et al ( , 1994b) that chemisorption of ethyl xanthate begins at À350 mV. However, the FTIR spectra obtained by Woods et al (1992) did not show the presence of chemisorbed xanthate at potentials below À150 mV. On the other hand, Leppinen et al (1991) observed absorption band at $1200 cm À1 below À200 mV, indicating the presence chemisorbed xanthate on silver.…”

“…This finding can be attributed to chemisorption (or under potential deposition) of xanthate, which is known to occur at potentials below the thermodynamic potential. It has been shown that the chemisorption of ethyl xanthate begins to occur approximately 150 mV below the reversible potential (Woods et al, 1992), which has also been found to be the case in the present work. Thus, the dixanthogen formed by anodic oxidation (Eq.…”

“…The measurements were conducted with gold-coated surfaces treated in 10 À3 M KEX solutions for 2 min. oxide formation as shown by E h -pH diagram (Woods et al, 1992). In the presence of xanthate, a strong anodic current peak was observed beginning at about À100 mV due to xanthate adsorption.…”

Comment on “In Situ and Ex Situ Infrared Studies of Nature and Structure of Thiol Monolayers Adsorbed on Cuprous Sulfide at Controlled Potential. Simulation and Experimental Results”

“…They state that “the single band at about 1225 cm -1 was observed also on silver and gold at a very low reducing potential”, i.e., below the region in which voltammetric studies show the prewave to commence. More recent studies at the VCCMP on the ethyl xanthate/silver system have demonstrated, however, that the band is absent at such potentials if care is taken to remove xanthate from the surface before exposure to the atmosphere. Thus, when the electrode surface was rinsed with deoxygenated xanthate-free solution immediately following opening of the circuit, the potential dependence of the intensity of the band closely paralleled that of voltammetric currents.…”