Abstract
The adsorption of Ca, Zn, and Cd ions at the solid/water interface was studied using second harmonic generation (SHG). Specifically, we used the SHG -(3) technique to assess and evaluate metal adsorption at a bare fused quartz/water interface, as well as at a carboxylic acid functionalized fused quartz/water interface. Adsorption isotherms were obtained for the metals at each interface and were fit with the diffuse layer and triple layer models to obtain adsorption free energies, interfacial potentials, absolute adsorbate number densities, and interfacial charge densities. The carboxylic acid functionalized interface displayed lower adsorption free energies but higher adsorbed metal number densities than the bare fused quartz/water interface. We suggest that metal binding at the bare fused quartz/water interface is driven by the initial number of deprotonated surface sites and that it proceeds through an outer-sphere mechanism. In contrast, metal binding at the carboxylic acid functionalized interface is associated with carboxylic acid deprotonation at a substantial free energy cost and proceeds directly through metal-carboxylate interactions.
Original language | English (US) |
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Pages (from-to) | 2041-2052 |
Number of pages | 12 |
Journal | Journal of Physical Chemistry C |
Volume | 113 |
Issue number | 6 |
DOIs | |
State | Published - Feb 12 2009 |
Funding
INPE (Instituto Nacional de Pesquisas Espaciais), PETROBRAS, FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo), CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico), and ERSDAC, supported this study. We are grateful to ANP (Agência Nacional do Petróleo), for providing information about an exploratory well drilled by PETROBRAS in Salgado do Melão area. The authors also thank Dr Ícaro Vitorello, Dr. Jeff R. Harris, and anonymous reviewers for constructive criticism of the manuscript.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- General Energy
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films