The effect of Pb(II) species, pH and dissolved carbonate on the zeta potential at the quartz/aqueous solution interface

✍ Scribed by R. Herrera-Urbina; D.W. Fuerstenau

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 695 KB
• Volume: 98
• Category: Article
• ISSN: 0927-7757
• DOI: 10.1016/0927-7757(95)03110-y

✦ Synopsis

The zeta potential of quartz has been measured in CO2-free and air-saturated aqueous lead solutions to delineate the effect of pH and atmospheric COz on the adsorption of Pb(II) at the oxide/solution interface. Under CO2-free conditions, an addition of 10 -4 M total lead causes the zeta potential of quartz to reverse its sign from negative to positive in the pH range from 7 to 11. If lead solutions are prepared with air-saturated water, this zeta potential reversal is not observed. Computations of thermodynamic equilibria for the systems Pb(II)-H20 and Pb(II)-H20-CO2 indicate the predominance of lead hydroxo complexes in the pH range of positive zeta potentials under CO2-free conditions, and the precipitation of lead carbonate in suspensions prepared with air-saturated water. The charge reversal of lead-activated quartz in CO2-free dispersions seems to be related to the adsorption of lead hydroxo complexes. In the presence of air or carbonate additives, the negative zeta potentials of lead-activated quartz in the pH range from 7 to 10 may be due to specific adsorption of the bicarbonate anion.