Adsorption and polymerisation of silicic acid on ferrihydrite, and its effect on arsenic adsorption

Swedlund, Peter J.

doi:10.1016/s0043-1354(99)00055-x

Cited by 327 publications

(338 citation statements)

References 16 publications

Supporting

Mentioning

304

Contrasting

Unclassified

Order By: Relevance

“…A considerable increase in the adsorption of silicate occurred from pH 11 to 9, whereas a decrease in pH from 9 to 7 only contributed a minor change in spectral intensity. It is well known that silicate sorption onto iron oxyhydroxides has a maximum at a pH value around 9 [8,10,21,22], but this is not reflected in our spectra. The observed sorption should already have passed its maximum when reaching pH 7.…”

Section: The Effect Of Ph On Sorption and Desorption Of The Silicatesmentioning

confidence: 65%

“…However, in the reversed flotation of apatite from magnetite, Su et al observed that the selectivity of sodium silicate as depressant decreased when the dosage increased from 300 g t −1 (2.4 × 10 −4 mol L −1 ) to 500 g t −1 (4 × 10 −4 mol L −1 ) resulting in a less efficient dephosphorization of magnetite fines and proposed that the dispersion effect of sodium silicate played a key role at such a low concentration rather than the depressant effect [7]. Knowledge about silicate-metal oxide reactions is of course also important to better understand other industrial applications than 0021 flotation such as the synthesis of zeolites and iron oxide-silicate composites as well as interfacial reactions in environmental systems [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…Stumm and colleagues were among the pioneers, who elaborated a ligand-exchange model to explain and predict the adsorption of H 4 SiO 4 on goethite [8]. Other authors [10,19,20] have used but also developed this ligand-exchange model. Very recently, Hiemstra et al modelled silicate sorption onto goethite from 1.0 × 10 −4 to 1.0 × 10 −3 mol L −1 solutions using a modified surface complex model (CD-MUSIC distribution model) [21].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A study of sodium silicate in aqueous solution and sorbed by synthetic magnetite using in situ ATR-FTIR spectroscopy

Yang

Roonasi

Holmgren

2008

Journal of Colloid and Interface Science

167

105

View full text Add to dashboard Cite

The sorption of sodium silicate by synthetic magnetite (Fe 3 O 4 ) at different pH conditions (pH 7-11) and initial silicate concentrations (1 × 10 −3 and 10 × 10 −3 mol L −1 ) was studied using in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The analysis of infrared spectra of sodium silicate in solution as well as adsorbed on magnetite nano-particles clearly showed the evolution of different silicate species depending on pH and silica concentration. The silicate concentration studied (10 × 10 −3 mol L −1 ) contained polymeric or condensed silicate species at lower pH as well as monomers at high pH, as evident from infrared spectra. Condensation of monomers resulted in an increased intensity of absorptions in the high frequency part (>1050 cm −1 ) of the spectral region, which contains information about both silicate in solution and sorbed silicate viz. 1300 cm −1 -850 cm −1 . In the pH range studied, infrared spectra of sorbed silicate and sorbed silicate during desorption both indicated the presence of different types of surface complexes at the magnetite surface. The sorption mechanism proposed is in accordance with a ligand exchange reaction where both monodentate and bidentate complexes could exist at low surface loading level, the relative proportion of the complexes being due to both pH and concentration in solution. Oligomerization occurred on the magnetite surface at higher surface loading.

show abstract

Section: The Effect Of Ph On Sorption and Desorption Of The Silicatesmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A study of sodium silicate in aqueous solution and sorbed by synthetic magnetite using in situ ATR-FTIR spectroscopy

Yang

Roonasi

Holmgren

2008

Journal of Colloid and Interface Science

167

105

View full text Add to dashboard Cite

show abstract

“…It is well known that the concentration, modulus, and pH of sodium silicate solutions are the main factors determining selective silicate sorption on mineral surfaces and that the properties of the modifying agent is strongly influenced by the distribution of silicate species in solution viz. monomers, oligomers, higher polymers, and colloidal silica [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Kinetics of silicate sorption on magnetite and maghemite: An in situ ATR-FTIR study

Yang

Roonasi

Jolsterå

et al. 2009

Colloids and Surfaces A: Physicochemical and Engineering Aspect

View full text Add to dashboard Cite

a b s t r a c tAttenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to monitor the in situ sorption of sodium metasilicate from aqueous solution onto synthesized magnetite and maghemite particles in the pH range of 10.8-7.0 using silicate concentrations between 0.1 mM and 5 mM. The spectral data showed that both pH and silicate concentration had great influence on the interfacial reaction between soluble silicate and the iron oxide surfaces, regarding the amount adsorbed per unit mass of iron oxide and the surface species formed. A pH dependent sorption of silicate on iron oxides was observed, implying that a maximum sorption took place in the pH range of 9.5-7.0. All experiments showed a fast initial increase in the absorption intensity followed by a slower sorption stage which was strongly dependent on the concentration of silicate in solution and the pH value. The amount of sorption onto magnetite was 3-5 times larger than onto maghemite, but there was no significant difference in the line shape of corresponding absorption bands. At pH 8.5 and low concentration (≤0.1 mM), the silicate monomers dominate in solution and on the iron oxide surface also monomeric species were dominating as evident from the infrared band at 950 cm −1 . However, at higher concentration (0.4-5.0 mM), the dominating absorption band at about 1000 cm −1 shifted to higher frequency during the sorption indicating that oligomeric surface silicate species were formed on the iron oxide surface. Desorption of silicate from the surface of the iron oxides was easier to accomplish at low silicate concentration, whilst the highest concentration showed a comparatively low relative amount of desorbed silicate, suggesting that polymerized species had a stronger affinity for the iron oxide surface as compared to monomeric species.

show abstract

“…Afterwards, when FeOOH precipitated from the aqueous solution and coated on the surface of the residual fly ash, Fe-Si surface complex (typically, Fe-O-Si(OH) 3 ) formed in situ as reported in the previous literatures [21,22], hence blocked or retarded the transformation of initially formed FeOOH to crystalline iron oxides such as ferrihydrite, goethite and hematite.…”

Section: Stability Of Amorphous Feoohmentioning

confidence: 81%

Catalytic oxidation of Methyl Orange by an amorphous FeOOH catalyst developed from a high iron-containing fly ash

Zhang

2010

Chemical Engineering Journal

109

View full text Add to dashboard Cite

Adsorption and polymerisation of silicic acid on ferrihydrite, and its effect on arsenic adsorption

Cited by 327 publications

References 16 publications

A study of sodium silicate in aqueous solution and sorbed by synthetic magnetite using in situ ATR-FTIR spectroscopy

A study of sodium silicate in aqueous solution and sorbed by synthetic magnetite using in situ ATR-FTIR spectroscopy

Kinetics of silicate sorption on magnetite and maghemite: An in situ ATR-FTIR study

Catalytic oxidation of Methyl Orange by an amorphous FeOOH catalyst developed from a high iron-containing fly ash

Contact Info

Product

Resources

About