Oxalate sorption

Mesuere and Fish (1992) found that oxalate diminished the sorption of chromate onto goethite most effectively at low pH and when sorbate concentrations were near surface-saturation levels. Chromate significantly inhibited oxalate sorption over a wide range of pH (from 4 to 10). Balistrieri and Chao (1987) suggested that for a given anion concentration ratio, the competition sequence... 

This interpretation has been supported by a study of oxalate sorption on corundum modelled by the CD-MUSIC model involving ATR-IR spedroscopy (Johnson et al., 2004). A mononuclear bidentate complex was found up to 14 pmol/m, whereupon oxalate additionally adsorbed as an outer-sphere complex. Sorption of oxalate has also been studied on boehmite and corundum by Yoon et al. (2004) The peaks assigned to the inner-sphere complex in previous works (near 1286,1418,1700 and 1720 cmi) were claimed to arise from the presence of several species. Evidence for this phenomenon comes from the observation that peaks at 1286 and 1418 cm-i are shifted to 1297 and 1408 cm-i as the oxalate surface coverage increases. The authors finally postulated the existence of two species species "A" at 1286 and 1418 cmi, and species "B" at 1297 and 1408 cm-i, respectively, which were... 

Although in many. soils with tow P availability, significant desorption of sparingly soluble Pi forms requires at least millimolar concentration levels of specific carboxylates (e.g., citrate, oxalate) in the soil solution, much lower concentrations (0.1 mM) were necessary to reduce. soil adsorption of Pi, which was applied simultaneously with carboxylates (100). Thus, competition of carboxylates with Pi for P sorption sites in the soil matrix may be a mechanism that can. 

The effect of other inorganic anions (sulfate, molybdate, silicate), low molecular mass organic ligands (LMMOLs, such as oxalate, malate, citrate, tartrate and succinate), and fulvic or humic acid on the sorption of arsenate and arsenite onto variable charge minerals and soils has been studied (Roy et al. 1986 Grafe et al. 2001 Liu et al. 2001 Violante et al. 2005a,b). 

Fig. 8.45 Sorption of Cu on montmoriilonite as a function of (a) pH and (b) time-dependent release of soil-absorbed Cu by EDTA, citrate, and oxalate. (Lehman and Harter, 1984)...

Fig. 12.12 Top Fe and Fe release from syn- tion of goethite in 0.2 M H2C2O4/K2C2O4 mix-thetic goethite, CO2 production and con- tures underthe influence of UV light as measured sumption as a function oftime in the presence of by the level of consumed. Insert oxalate ad-0.025 M oxalate at pH 2.6 and 25 °C. Bottom The sorption by goethite as a function of pH (Cornell effect of pH on the rate of photochemical dissolu- Schindler, 1987, with permission).

Music, S. Gessner, M. Wolf, R.H.H. (1979b) Sorption of trace amounts of gallium(III) on iron(III) oxide. Radiodiim. Acta 26 51-53 Music, S. Gotic, M. Popovic, S. (1994) Formation of y-Fe203 by thermal decomposition of a mixture of Fe(II)- and Fe(III)-oxalate salts. 

The relative efficiency of various reagents in retrieving Cu, Pb, Cd or Zn ions presorbed onto clay suspension has been investigated [254], It was found that a few extractants (e.g., EDTA, oxalic acid) recovered all of the adsorbed metal ion. However, in most of the systems examined the extraction yield varied with the type of clay, the metal ion and the pH and concentration of the extractant, as well as with the pH during the initial sorption stage. 

Whereas several specific soil attributes are advocated as being responsible for DOC sorption in the mineral soil (Table V), it appears that the greater the clay or aluminum and iron oxide content of a soil, the greater its adsorptive capacity for DOC. For example, there is a positive correlation between m (the measure of the affinity of a substance for the sorbent or the partition coefficient) and soil clay content, dithionite extractable iron (Fej), and oxalate extractable aluminum (Al0) (Moore et al., 1992 Nelson et al., 1993 Kaiser and Zech, 1998). Direct measurements of the surface area of soil particles also correlate very well with DOC adsorption capacity (Nelson et al., 1993). Furthermore, Nelson et al. (1993) report that riverine DOC concentrations are negatively correlated to the clay content of watershed... 

Oxalic acid in the feed does not affect the sorption behavior of Cr + and Ni + ions on the cation resin. However, about 75% of the Ni(ll) ions were in the sorption and wash effluents because resin affinity for Ni + ion is lower than that for Cr + and Am + ions. 

Xia, K. Pierzynski, G. Competitive Sorption between Oxalate and Phosphate in Soil An En-... 

At 2x10" and 8x10" mol dm" of both ions presence of oxalate does not affect sorption of chromate, but sorption of oxalate is depressed in the presence of chromate. The uptake of chromate is depressed at a 4x excess of oxalate. 

Figure 5.5. Effect of increasing concentrations of oxalate (OX) on the sorption of Cu onto goethite and Pb onto ferrihydrite. The initial concentration of Cu and Pb was 40 and 117 mmol kg, respectively. (Modified from Zhou et al., 1999 and Violante et al., 2003.)...

The influence of LMMOLs on the sorption of Pb onto different metal oxides as affected by the sequence of addition of Pb and LMMOLs [oxalate (OX) or tartrate (TR)] on the sorbents was studied by Violante et al. (2003). These authors determined the amounts of Pb sorbed at pH 4.0 when added alone (Pb) or in the... 

Plutonium(III) oxalate. If the plutonium solution from fuel reprocessing is concentrated by sorption on a cation-exchange resin, the plutonium eluent will be a nitrate solution of stabilized trivalent plutonium. This solution may be a logical candidate for the relatively simple precipitation of Pu(III) oxalate. The Pu(III) oxalate Puj(C2 04)3 9H2 0 can be easily precipitated by adding oxalic acid, either as a solution or a solid. Precipitation conditions are not critical, and the Pu(III)... 

FIGURE 9,33 Relationship between oxalate-extractable iron and aluminum and phosphate sorption maximum of mineral wetland soils. (Adapted from Reddy et al., 1995.)... 

FIGURE 9.34 Relationship between oxalate-extractable aluminum and phosphate sorption in mineral and peat-based wetlands. (Adapted from Richardson, 1985.)... 

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