Details
| Original language | English |
|---|---|
| Pages (from-to) | 650-657 |
| Number of pages | 8 |
| Journal | European Journal of Soil Science |
| Volume | 68 |
| Issue number | 5 |
| Early online date | 26 Jul 2017 |
| Publication status | Published - Sept 2017 |
Abstract
Aggregation properties of iron oxide particles have received much attention because of their environmental importance in soil and aquatic environments. The effects of silicic acid on the pH-dependent surface charges that govern the aggregation of goethite have received little attention. In this study we determined the effect of silicic acid as a function of pH and ionic strength (IS) on the aggregation of a synthetic goethite by a combination of particle-size analysis using dynamic light scattering and test tube experiments to quantify particles in suspension. We investigated silicic acid adsorption on goethite quantitatively by batch adsorption isotherms, and the changes in surface charge on the adsorption of silicic acid were identified by the zeta potential (ζ). Our results revealed that silicic acid can lead to a significant decrease in ζ. A change in the pHiep (iep: isoelectric point) from 8.5 to lower pH values, typically pH 4–5.5, in the presence of silicic acid suggests enhanced aggregation of goethite in the acidic pH range. At alkaline pH, both goethite and silicic acid were negatively charged because of strong deprotonation, and silicic acid adsorption promoted goethite dispersion. Ionic strength affected the aggregation of goethite by shifting ζ towards the iep and it can also obscure the role of silicic acid. Highlights: Effect of silicic acid on surface charge and aggregation of goethite was investigated. Adsorption of silicic acid reduces ζ and allows goethite to aggregate at lower pH. Ionic strength can also affect aggregation of goethite by shifting ζ towards the isoelectric point. Silicic acid in soil might maintain goethite particles in an aggregated state.
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Soil Science
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In: European Journal of Soil Science, Vol. 68, No. 5, 09.2017, p. 650-657.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Effect of silicic acid on the aggregation properties of goethite
AU - Nguyen, Minh N.
AU - Picardal, F.
AU - Dultz, Stefan
AU - Nguyen-Thanh, Lan
AU - Dam, Than T.N.
AU - Nguyen, Khai M.
N1 - Funding information: This research was funded by the Vietnam National Foundation for Science & Technology Development (Project 105.09-2015.01). We would also like to thank the School of Public and Environmental Affairs and the Office of the Vice President of International Affairs, Indiana University, for funding assistance, and Professors David Bish and Erika Elswick, Department of Geological Sciences, Indiana University, for their helpful analytical guidance. We are grateful to Elisabeth Andrews for editorial assistance.
PY - 2017/9
Y1 - 2017/9
N2 - Aggregation properties of iron oxide particles have received much attention because of their environmental importance in soil and aquatic environments. The effects of silicic acid on the pH-dependent surface charges that govern the aggregation of goethite have received little attention. In this study we determined the effect of silicic acid as a function of pH and ionic strength (IS) on the aggregation of a synthetic goethite by a combination of particle-size analysis using dynamic light scattering and test tube experiments to quantify particles in suspension. We investigated silicic acid adsorption on goethite quantitatively by batch adsorption isotherms, and the changes in surface charge on the adsorption of silicic acid were identified by the zeta potential (ζ). Our results revealed that silicic acid can lead to a significant decrease in ζ. A change in the pHiep (iep: isoelectric point) from 8.5 to lower pH values, typically pH 4–5.5, in the presence of silicic acid suggests enhanced aggregation of goethite in the acidic pH range. At alkaline pH, both goethite and silicic acid were negatively charged because of strong deprotonation, and silicic acid adsorption promoted goethite dispersion. Ionic strength affected the aggregation of goethite by shifting ζ towards the iep and it can also obscure the role of silicic acid. Highlights: Effect of silicic acid on surface charge and aggregation of goethite was investigated. Adsorption of silicic acid reduces ζ and allows goethite to aggregate at lower pH. Ionic strength can also affect aggregation of goethite by shifting ζ towards the isoelectric point. Silicic acid in soil might maintain goethite particles in an aggregated state.
AB - Aggregation properties of iron oxide particles have received much attention because of their environmental importance in soil and aquatic environments. The effects of silicic acid on the pH-dependent surface charges that govern the aggregation of goethite have received little attention. In this study we determined the effect of silicic acid as a function of pH and ionic strength (IS) on the aggregation of a synthetic goethite by a combination of particle-size analysis using dynamic light scattering and test tube experiments to quantify particles in suspension. We investigated silicic acid adsorption on goethite quantitatively by batch adsorption isotherms, and the changes in surface charge on the adsorption of silicic acid were identified by the zeta potential (ζ). Our results revealed that silicic acid can lead to a significant decrease in ζ. A change in the pHiep (iep: isoelectric point) from 8.5 to lower pH values, typically pH 4–5.5, in the presence of silicic acid suggests enhanced aggregation of goethite in the acidic pH range. At alkaline pH, both goethite and silicic acid were negatively charged because of strong deprotonation, and silicic acid adsorption promoted goethite dispersion. Ionic strength affected the aggregation of goethite by shifting ζ towards the iep and it can also obscure the role of silicic acid. Highlights: Effect of silicic acid on surface charge and aggregation of goethite was investigated. Adsorption of silicic acid reduces ζ and allows goethite to aggregate at lower pH. Ionic strength can also affect aggregation of goethite by shifting ζ towards the isoelectric point. Silicic acid in soil might maintain goethite particles in an aggregated state.
UR - http://www.scopus.com/inward/record.url?scp=85026326484&partnerID=8YFLogxK
U2 - 10.1111/ejss.12453
DO - 10.1111/ejss.12453
M3 - Article
AN - SCOPUS:85026326484
VL - 68
SP - 650
EP - 657
JO - European Journal of Soil Science
JF - European Journal of Soil Science
SN - 1351-0754
IS - 5
ER -