Bridging the Gap between Macroscopic and Spectroscopic Studies of Metal Ion Sorption at the Oxide/Water Interface:  Sr(II), Co(II), and Pb(II) Sorption to Quartz

Abstract

Metal sorption mechanisms were investigated for strontium, cobalt, and lead using sodium chloride, sodium nitrate, and sodium perchlorate as background electrolytes and quartz as the adsorbent. Spectroscopic analyses of concentrated sorption samples were evaluated for their ability to provide insight into the controlling sorption process for more dilute systems. For strontium, outersphere complexes identified using X-ray absorption spectroscopy (XAS) of concentrated samples were consistent with macroscopic sorption data collected in more dilute systems. XAS results indicated that cobalt formed a new solid phase upon sorption to silica. Macroscopic studies of cobalt sorption supported the spectroscopic data for total cobalt concentrations of 10 -5 M, regardless of the background electrolyte composition or concentration. At a lower total cobalt concentration (10 -7 M), adsorption appeared to be the prevailing mechanism of cobalt removal. Spectroscopic results suggested that lead adsorbed as an inner-sphere complex on silica. The decrease of lead removal with increasing chloride concentration was attributed to competition with aqueous lead-chloride complexes, based on thermodynamic calculations.

Surface complexation modeling of Co(II) adsorption on mixtures of hydrous ferric oxide, quartz and kaolinite

“…The Co sorption edges measured on quartz in this study are generally in good agreement with those reported in the literature (Table EA-3). X-ray absorption spectroscopy has also been used to investigate Co sorption on quartz under a range of pH, background electrolyte and sorbate/sorbent conditions (Charlet and Manceau, 1994;O'Day et al, 1996;Manceau et al, 1999;Chen et al, 2006). O'Day et al (1996) used surface coverages of 0.77 to 9.21 lmol/ m 2 , considerably higher than the surface coverages of 0.05 to 0.50 lmol/m 2 used in this study.…”

“…5). Adsorption decreases with increasing ionic strength, with the pH 50 dropping from $8.4 at 0.1 M to $6.9 at 0.001 M. The increase in Co sorption observed at low pH, particularly for the low ionic strength and sorbate/sorbent ratios, may indicate the presence of a second phase, e.g., Fe or Al oxide, as the quartz was not prewashed (Kohler et al, 1996;Chen et al, 2006). However, X-ray diffraction patterns of quartz did not change after repeated washing in concentrated nitric acid (data now shown) and ICP analyses of supernatants showed no detectable Co, Cd, Cu, Mn, Ni, Pb or Sb and <10 ppb Tl, Fe, As or Ba.…”

“…The adsorption of Co as a function of pH has been studied using macroscopic laboratory methods on simple solids including hydrous ferric oxide (Kurbatov et al 1951a,b;Kurbatov and Wood, 1952;Duval and Kurbatov, 1952;Benjamin and Bloom, 1981;Benjamin, 1983;Dzombak and Morel, 1990;Ainsworth et al, 1994), kaolinite (Angove et al, 1998;Benyahya and Garnier, 1999;Chen and Hayes, 1999;Ikhsan et al, 1999) and quartz or silica (James and Healy, 1972;O'Day et al 1996;Chen and Hayes, 1999;Berka and Banyai, 2001;Chen et al, 2006). X-ray absorption spectroscopy has been used to characterize the nature of Co surface complexes on quartz (Charlet and Manceau, 1994;O'Day et al, 1996;Manceau et al, 1999;Chen et al, 2006) and several clay minerals (Chisholm-Brause et al, 1990;O'Day et al, 1994;Charlet and Manceau, 1994;Chen and Hayes, 1999;Schlegel et al, 1999a,b;Thompson et al, 1999Thompson et al, , 2000.…”

“…X-ray absorption spectroscopy has been used to characterize the nature of Co surface complexes on quartz (Charlet and Manceau, 1994;O'Day et al, 1996;Manceau et al, 1999;Chen et al, 2006) and several clay minerals (Chisholm-Brause et al, 1990;O'Day et al, 1994;Charlet and Manceau, 1994;Chen and Hayes, 1999;Schlegel et al, 1999a,b;Thompson et al, 1999Thompson et al, , 2000. These data have aided the development of surface complexation models to describe Co adsorption on a variety of sorbents.…”

The use of short‐lived radionuclides to quantify transitional bed material transport in a regulated river

“…Because 7 Be 2+ is electronegative, it will tend to form strong covalent bonds with oxygen atoms at these grain boundaries. Direct evidence of trace metal adsorption to inorganic silica, alumina and iron mineral surfaces is given by numerous X-ray studies (Cheah et al, 1998(Cheah et al, , 2000Chen et al, 2006)). Furthermore, You et al (1989) measured the partitioning coefficient (K d ) of 7 Be on a range of natural substances, including river sands (presumably dominated by quartz and feldspar), lake muds, soils, crushed carbonate mineral separates, and crushed beryl mineral separates.…”