Adsorption Kinetics of Pentachloroethane by Iron-Bearing Smectites

Cervini-Silva, Javiera; Wu, Jun; Stucki, Joseph W.; Larson, Richard A.

doi:10.1346/ccmn.2000.0480116

Cited by 29 publications

(38 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Linear regression analysis of the data was performed using analysis of variance (ANOVA) with 95% confidence intervals. The results listed in Table 1 agree with previous work [13,14,19] in that the k obs increases with the reduction of the structural Fe of the clay. The trend of RCl adsorption in the presence of SWa-U ) differed from the trend of RCl…”

Section: Resultssupporting

confidence: 90%

“…h ϭ the number of degrees of freedom. vious reports [13,14] The trend in RCl reactivity in the presence of redox-manipulated smectites was compared to the trend in reactivity of RCl in the presence of other Fe(II)-bearing aqueous systems such as iron porphyrins, iron sulfide, or commercial Fe ( Table 4). The trend in reactivity of RCl toward SWa-R displayed acceptable correlation (r 2 ϭ 0.83, p Ͻ 0.5) only with the reported trend in reactivity of RCl toward FeS (10 g/L, t Յ 2,000 h, pH ϭ 8.3 [36,42]).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Linear free‐energy relationship analysis of the fate of chlorinated 1‐ and 2‐carbon compounds by redox‐manipulated smectite clay minerals

Cervini-Silva

2003

Enviro Toxic and Chemistry

Self Cite

View full text Add to dashboard Cite

This paper expands on earlier work on the effect of molecular structure on the fate of a series of chlorinated 1- and 2-carbon compounds (RCl), including carbon tetrachloride, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, trichloroethene, tetrachloroethene, trichloronitromethane, and trichloroacetonitrile, in the presence of unaltered (SWa-U) and reduced (SWa-R) ferruginous smectite. A linear free-energy relationships (LFERs) analysis was conducted to explain kinetic data for RCl adsorption and dechlorination. Correlation analyses based on RCl hydration energies, hydrolysis rate constants, or bond dissociation energies were significant (r2 > 0.87) for RCl adsorption by SWa-R but not so for RCl adsorption by SWa-U (r2 < 0.5). The most statistically significant relationships describing RCl kinetic data were achieved using multivariable regression analysis including RCl hydration energies (or hydrolysis rate constant) and bond dissociation energies for RCl heterolysis. The outcome of this study indicates that the oxidation state of structural Fe in the clay strongly influences RCl hydration. A mechanism consistent with the present LFERs analysis corresponds to RCl hydration as the limiting step for adsorption and dechlorination by redox-manipulated smectites.

show abstract

Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Linear free‐energy relationship analysis of the fate of chlorinated 1‐ and 2‐carbon compounds by redox‐manipulated smectite clay minerals

Cervini-Silva

2003

Enviro Toxic and Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…Surface alkalinity rather than surface acidity, however, may be the more correct surface property accounting for the effect of Fe oxidation state on atrazine sorption/degradation. Cervini‐Silva et al [36] recently reported that the Brønsted basicity of smectite surfaces is greater in the reduced than in the oxidized state. This is attributed to a greater electron density at basal oxygens due to reduction of Fe(III) to Fe(II) in the structure.…”

Section: Resultsmentioning

confidence: 99%

Fate of atrazine and alachlor in redox‐treated ferruginous smectite

Stucki

et al. 2001

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

The oxidation state of structural iron (Fe) in clay minerals exerts a large influence on clay surface chemistry and may affect the adsorption and degradation of pesticides in the environment. This effect, however, has been little investigated. In the present study, herbicides atrazine and alachlor were reacted with ferruginous smectite (sample SWa-1) in its oxidized, reduced (either chemically or bacterially), and reduced-reoxidized states. In some experiments the herbicide was labeled with 14C. Gas chromatography/mass spectrometry (GC-MS) was also used to detect alachlor degradation products. Compared to oxidized clays, reduction by both chemical and microbial treatments decreased the concentration of both herbicides in the surrounding solution. Reoxidized clay exhibited behavior similar to the oxidized clay. Hydrolysis-dechlorination of atrazine occurred in the presence of chemically reduced SWa-1, and GC-MS analysis of alachlor revealed at least 14 degradation products after treatment with reduced clay and only two with the oxidized clay. Interaction of atrazine and alachlor with the clay may be through a H bond with the waters of hydration surrounding interlayer cations, the extent of which should increase with increasing acidity; but under reduced conditions, the validity of this model is unclear. Reduction of structural Fe may affect pH-dependent phenomena in two ways: The increased surface charge density increases the number of hydrated interlayer cations, thereby enhancing surface acidity, and increased electron density at basal surface oxygens increases their Brønsted basicity. Atrazine could, therefore, adsorb and/or degrade through either acid or alkaline hydrolysis pathways. Increased reduction potential of the reduced clay surfaces may also promote degradation.

show abstract

“…Among them, metallic ions play a significant catalytic role during sorption (Cervini-Silva et al, 2000;Saidy et al, 2013). In addition to simple surface sorption, other studies have suggested that encapsulation into micro pore and nano pore spaces can also prevent bacterial enzyme access, aiding the preservation of "metabolizable" OM (Kaiser and Guggenberger, 2007;Curry et al, 2007;Mayer,2004).…”

Section: Introductionmentioning

confidence: 99%

Organic matter and clay interaction in a meromictic lake: Implications for source rock OM preservation (Lac Pavin, Puy-de-Dôme, France)

Ahmat

Boussafir

Milbeau

et al. 2017

Organic Geochemistry

View full text Add to dashboard Cite

International audienceInvestigation of organic matter (OM) preservation mechanisms is crucial for understanding organic accumulation in sedimentary environments. We focus here on the contribution of organo-clay interaction in such preservation. Most studies addressing this issue deal with organo-mineral complexes which have settled, omitting consideration of early aggregation within the water column. We therefore investigated the sorption of OM on montmorillonite (Na MMt) and kaolinite (Kaol) immersed in a permanently stratified water column (Lake Pavin, France). The two types of clay samples were kept immersed for different lengths of time and characterized via analytical methods suited for the organic phase [pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), GC-MS, Fourier transform infrared spectroscopy (FT-IR) and dissolved organic carbon (DOC) analysis, as well as for the mineral phase [X ray diffraction (XRD) and microprobe elementary cartography]. Results suggest that strong organo-clay interaction occurred within the water column to a varying extent depending on water physicochemical conditions and the mineral phase typology. A higher concentration of DOC was observed in the proximal environment of the clay traps, suggesting an attractive effect induced by the clay minerals. Lipid compounds sorbed during the immersion were essentially fatty acids and aromatic compounds. Their distributions were closer to a phytoplankton signature than allochtonous pedogenetic OM.The sorption was particularly efficient in the O2 transition zone, with a greater amount of OM on Na-MMt than Kaol. This was principally due to the high specific surface area and cationic exchange capacity (CEC) of the 2/1 clay mineral. Besides, XRD characterization revealed an increase in Na MMt interlayer spacing, which did not necessarily correspond to organic intercalation.The study confirms that the sorption of dissolved OM cannot alone explain the preservation of hydrocarbon-rich OM in such a lacustrine environment. Indeed, the sorbed OC was very low compared with the amount proposed by several authors as an expression of the monolayer equivalent principle

show abstract

Adsorption Kinetics of Pentachloroethane by Iron-Bearing Smectites

Cited by 29 publications

References 20 publications

Linear free‐energy relationship analysis of the fate of chlorinated 1‐ and 2‐carbon compounds by redox‐manipulated smectite clay minerals

Linear free‐energy relationship analysis of the fate of chlorinated 1‐ and 2‐carbon compounds by redox‐manipulated smectite clay minerals

Fate of atrazine and alachlor in redox‐treated ferruginous smectite

Organic matter and clay interaction in a meromictic lake: Implications for source rock OM preservation (Lac Pavin, Puy-de-Dôme, France)

Contact Info

Product

Resources

About