Phosphate effects on cadmium(II) sorption to ferrihydrite
2016 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 471, 103-111 p.Article in journal (Refereed) PublishedText
Hypothesis: Phosphate influences the sorption of metals to iron (hydr)oxides. An enhanced formation of inner-sphere complexes on the (hydr)oxide surface can be attributed to electrostatic interactions and/or to changes in metal coordination on the iron (hydr)oxide surface. Phosphate was expected to increase cadmium(II) sorption on ferrihydrite. It should be possible to identify changes in cadmium(II) coordination upon phosphate addition by Extended X-ray absorption fine structure (EXAFS) spectroscopy and implement the identified complexes in a surface complexation model (SCM). Experiments: The effect of phosphate addition on cadmium(II) sorption to ferrihydrite was studied by a series of batch experiments covering the pH range from 4 to 8. EXAFS spectroscopy was performed on ferrihydrite from the batch experiments at the cadmium K edge. The identified surface complexes were incorporated in the Charge distribution multisite complexation (CD-MUSIC) model, and new surface complexation constants were optimized. Findings: Without phosphate addition cadmium(II) formed inner-sphere bidentate complexes on the ferrihydrite surface. With phosphate there was an increased cadmium(II) sorption that could not be explained by electrostatic interactions alone. The enhancement was best explained by the formation of a ternary complex including cadmium(II), phosphate and ferrihydrite surface groups.
Place, publisher, year, edition, pages
Academic Press Inc. , 2016. Vol. 471, 103-111 p.
Adsorption, Cadmium (Cd), Charge distribution multisite complexation (CD-MUSIC), Extended X-ray absorption spectroscopy (EXAFS), Iron hydroxide, Iron oxide, Phosphate, Surface complex, Cadmium, Charge distribution, Coordination reactions, Electrostatics, Extended X ray absorption fine structure spectroscopy, Hydraulic servomechanisms, Iron, Iron oxides, Phosphates, Sorption, X ray absorption spectroscopy, Cadmiums (Cd), Extended x-ray absorption spectroscopies, Iron hydroxides, Multi-site, Iron compounds
Chemical Engineering Geochemistry
Research subject Land and Water Resources Engineering
IdentifiersURN: urn:nbn:se:kth:diva-186957DOI: 10.1016/j.jcis.2016.03.016ISI: 000374511900014ScopusID: 2-s2.0-84960923174OAI: oai:DiVA.org:kth-186957DiVA: diva2:930566
QC 201605242016-05-242016-05-162016-06-20Bibliographically approved