EXAFS study of chromated copper arsenate timber preservative in wood

Bull, David C.; Harland, Peter W.; Vallance, Claire; Foran, Garry J

doi:10.1007/bf00776457

Cited by 19 publications

(20 citation statements)

References 10 publications

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“…The As-Cr distance is ca. 3.25 Å [43] and is similar to that of As-Cu in the clinoclase and monoclinic olivenite structures [36,37]. In the presence of Zn, the number of Cu neighbours at 3.21 Å decreased by ca.…”

Section: Minerals and Precipitatessupporting

confidence: 61%

Arsenic speciation in multiple metal environments: I. Bulk-XAFS spectroscopy of model and mixed compounds

Gräfe

Tappero

Marcus

et al. 2008

Journal of Colloid and Interface Science

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X-ray absorption fine structure (XAFS) spectroscopy was employed to determine the bonding environment of As(V) in the presence of Cu(II) and Zn(II) on goethite and gibbsite. In addition, several mineral species and precipitates derived from homogeneous and heterogeneous (presence of α-Cr 2 O 3 ) super-saturations were studied. Structural parameters were determined after resolving the broad second shells in r-space by differential k-weighting (1, 2 or 3) and k-ranging (2.5-vs 3.5-12.75 Å) of the raw EXAFS functions. In precipitates, AsO 4 was incorporated in the metal-hydroxides forming clinoclase-like and koettigite-like structures in the presence of Cu(II) and Zn(II), respectively. In the presence of both Cu(II) and Zn(II), the clinoclase structure formed preferentially over the koettigite structure under homogeneous oversaturated solution conditions and in the presence of eskolaite (α-Cr 2 O 3 ). Silica promoted the formation of koettigite-like zinc-arsenate precipitates from initial As(V) and Zn(II) solution concentrations of 500 µM. On goethite and gibbsite, 750 µM As(V) formed mainly bidentate binuclear surface species in accordance with many previous findings even in the presence of equimolar Cu(II) and or Zn(II) concentrations. Copper was readily identified in the second shell environment of As(V) sorbed on gibbsite, but not on goethite. We hypothesize that this complex formed on the basis of Cu(II)'s ability to form polymeric species in solution and at the mineral-water interface in agreement with previous studies. The effects of Zn(II) on the coordination environment of As(V) on gibbsite and goethite could not be ascertained with As K-edge EXAFS spectroscopy. In addition to bidentate binuclear surface complexes, As(V) formed edge-sharing complexes with Fe, Al, and Cu atoms, which we could differentiate on the basis of the inter-atomic distances, phase shifts between wavefunctions of Fourier-filtered peaks, and differences in amplitude of the absorption envelopes. The analyses showed that of all data reduction steps, data presented in r-space and as wavefunctions of Fourier-filtered shells offer the greatest possibility for fingerprinting and inferring the influence of co-sorbing metal cations on the As(V) sorption complex. With regards to interpretations of micro-EXAFS data by abstract factor analyses and linear least-square combination fitting, analyses of As K-edge data should not be performed on the raw χ(k) data, but rather on consistently isolated second and higher-order shell features.

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Section: Minerals and Precipitatessupporting

confidence: 61%

Arsenic speciation in multiple metal environments: I. Bulk-XAFS spectroscopy of model and mixed compounds

Gräfe

Tappero

Marcus

et al. 2008

Journal of Colloid and Interface Science

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“…For the modelling purposes, we assumed that Cr is mainly present as Cr(III), Cr(OH) 2 + , because Cr(VI) is reduced to Cr(III) in the impregnation process and it is mainly leaching from CCA-wood as Cr(III) [35,39,43]. Based on the results, oxalic acid does not affect the speciation of Cr(III) and it is exclusively present as cations at pH ≤ 5.…”

Section: Removal Of Chromiummentioning

confidence: 98%

“…Furthermore, saturation indexes >1 suggest that some of Cu hydroxides [Cu(OH) 2 ] and tenorite (CuO) might precipitate and also trap As in the form of Cu 3 (AsO 4 ) 2 ·2H 2 O. Bull et al [35] have reported on the formation of a similar mineral, euchroite, Cu 2 (OH)AsO 4 ·3H 2 O. Thus, low pH conditions (<5) would be the most favourable for efficient electromigration of the small divalent Cu cations towards the cathode, and at least the maximum pH should be maintained at <10 to avoid precipitation of Cu hydroxides, co-precipitation of As and reversal in ionic charge.…”

Section: Removal Of Coppermentioning

confidence: 99%

“…Wood and lignin materials in general have a high sorption capacity for metals, which has been utilized for wastewater purification [33,34]. It is known that in wood that has been impregnated with CCA (CuO, CrO 3 , As 2 O 5 ), As(V) and Cr(VI) that has become reduced to Cr(III) exist predominantly as chromium(III)arsenate, chromium(III)hydroxide and copper(II)-wood carboxylate complexes [35,36]. As and Cr that leach from CCA-treated wood appear to be mainly in the oxidation states As(V) and Cr(III) [37][38][39].…”

Section: Introductionmentioning

confidence: 99%

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Sequential electrokinetic treatment and oxalic acid extraction for the removal of Cu, Cr and As from wood

Isosaari

Marjavaara

Lehmus

2010

Journal of Hazardous Materials

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“…However, dithionite extracts predominantly Al 3+ substituted for Fe 3+ in poorly and well crystalline iron oxides (26,27). Pyrophosphate is a selective extractant for organic complexes of Al and Fe, but Kaiser and Zech (28) showed that pyrophosphate can also extract some non-crystalline Al(OH) 3 .…”

Section: Methodsmentioning

confidence: 99%

Arsenic and Chromium Partitioning in a Podzolic Soil Contaminated by Chromated Copper Arsenate

Hopp

Nico

Marcus

et al. 2008

Environ. Sci. Technol.

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This research combined the use of selective extractions and x-ray spectroscopy to examine the fate of As and Cr in a podzolic soil contaminated by chromated copper arsenate (CCA). Iron was enriched in the upper 30 cm due to a previous one-time treatment of the soil with Fe(II). High oxalate-soluble Al concentrations in the Bs horizon of the soil and micro-XRD data indicated the presence of short-range ordered aluminosilicates (i.e. proto-imogolite allophane, PIA). In the surface layers, Cr, as Cr(III), was partitioned between a mixed Fe(III)/Cr(III) solid phase that formed upon the Fe(II) application (25-50%) and a recalcitrant phase (50-75%) likely consisting of organic material such as residual CCA-treated wood. Deeper in the profile Cr appeared to be largely in the form of extractable (hydr)oxides. Throughout the soil, As was present as As(V). In the surface layers a considerable fraction of As was also associated with a recalcitrant phase, probably CCA-treated woody debris, and the remainder was associated with (hydr)oxide-like solid phases. In the Bs horizon, however, XAS and XRF findings strongly pointed to the presence of PIA acting as an effective adsorbent for As. This research shows for the first time the relevance of PIA for the adsorption of As in natural soils.

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EXAFS study of chromated copper arsenate timber preservative in wood

Cited by 19 publications

References 10 publications

Arsenic speciation in multiple metal environments: I. Bulk-XAFS spectroscopy of model and mixed compounds

Arsenic speciation in multiple metal environments: I. Bulk-XAFS spectroscopy of model and mixed compounds

Sequential electrokinetic treatment and oxalic acid extraction for the removal of Cu, Cr and As from wood

Arsenic and Chromium Partitioning in a Podzolic Soil Contaminated by Chromated Copper Arsenate

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