HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (37) Citing Articles via Google Scholar Google Scholar Articles by Su, C. Articles by Suarez, D. L. Search for Related Content PubMed Articles by Su, C. Articles by Suarez, D. L. GeoRef GeoRef Citation Agricola Articles by Su, C. Articles by Suarez, D. L.

Selenate and Selenite Sorption on Iron Oxides

An Infrared and Electrophoretic Study

^a ManTech Environmental Research Services Corp., R.S. Kerr Environmental Research Center, 919 Kerr Research Drive, Ada, OK 74821-1198 USA
^b USDA-ARS, U.S. Salinity Lab., 450 W. Big Springs Road, Riverside, CA 92507-4617 USA

View larger version (25K): [in a new window]   Fig. 1 Percent of the total Se added to solution that is sorbed to am-Fe(OH)3 as a function of pH and ionic strength with (a) 0.1 mM total Se, and (b) 1.0 mM total Se. The solid concentration was 4.0 g L-1

View larger version (25K): [in a new window]   Fig. 2 Percent of the total Se added to solution that is sorbed to goethite as a function of pH and ionic strength with (a) 0.1 mM total Se, and (b) 1.0 mM total Se. The solid concentration was 4.0 g L-1

View larger version (24K): [in a new window]   Fig. 3 Sorption–desorption isotherms for am-Fe(OH)3 in 0.01 M NaCl at pH 5.0, showing natural logarithm of Se sorbed as a function of the logarithm of the equilibrium Se concentration: (a) selenate and (b) selenite. The solid concentration was 4.0 g L-1. Desorption was performed following centrifugation of suspensions after a 24-h equilibration for sorption. Each desorption process involved a 24-h equilibration in 0.01 M NaCl at pH 5.0 followed by centrifugation. Numbers in parantheses represent initial selenate concentrations of 4, 6, 8, and 10 mM

View larger version (26K): [in a new window]   Fig. 4 Sorption–desorption isotherms for goethite in 0.01 M NaCl at pH 5.0: (a) selenate and (b) selenite. Experimental conditions were the same as in Fig. 3 except that the initial Se concentrations were one-tenth of those for am-Fe(OH)3

View larger version (31K): [in a new window]   Fig. 5 Electrophoretic mobility of (a) am-Fe(OH)3 and (b) goethite in 0.01 M NaCl with and without added Se. The suspensions were acidified to pH 3.0 with HCl and then titrated with 0.01 M NaOH. Initial solid concentration was 0.2 g L-1

View larger version (29K): [in a new window]   Fig. 6 The attenuated total reflectance–Fourier transform infrared (ATR–FTIR) difference spectra of selenate and selenite in aqueous solution (spectrum of 0.1 M Na2SeO4 or 1.0 M Na2SeO3 in 1.0 M NaCl at pH 5.0 or 8.0 - spectrum of 1.0 M NaCl at pH 5.0 or 8.0). The subtraction factor was unity. The spectra are offset for clarity

View larger version (30K): [in a new window]   Fig. 7 The attenuated total reflectance–Fourier transform infrared (ATR–FTIR) difference spectra of am-Fe(OH)3 equilibrated at pH 5.0 with (a) 0.1 M Na2SeO4 + 1.0 M NaCl, (b) 0.05 M Na2SeO4 + 1.0 M NaCl, and (c) 1.0 M NaCl alone. The BET N2 surface area of am-Fe(OH)3 was 250 m2 g-1.The subtracted reference spectra were the supernatant solutions. The initial solid concentration was 200 g L-1 before centrifugation and the solid concentration in the ATR reservoir was 1000 g L-1. The interfacial selenate spectra were presented as (a–c) and (b–c), respectively

View larger version (17K): [in a new window]   Fig. 8 Spectral deconvolution of the attenuated total reflectance–Fourier transform infrared (ATR–FTIR) difference spectra (b–c) from Fig. 7

View larger version (30K): [in a new window]   Fig. 9 Diffuse reflectance infrared Fourier transform (DRIFT) difference spectra of sorbed selenate on am-Fe(OH)3 reacted at pH 5.0 with (a) 0.10 M Na2SeO4 + 1.0 M NaCl, and (b) 0.05 M Na2SeO4 + 1.0 M NaCl. The reference spectrum for (a) and (b) was the am-Fe(OH)3 equilibrated with 1.0 M NaCl. The solid to KBr ratio was 5 to 95 mg. Regent grade Na2SeO4 (c) was included for comparison. The BET N2 surface area of am-Fe(OH)3 was 250 m2 g-1

View larger version (21K): [in a new window]   Fig. 10 Diffuse reflectance infrared Fourier transform (DRIFT) difference spectra of sorbed selenate on am-Fe(OH)3 reacted at pH 5.0 with 0.01 M Na2SeO4 + 1.0 M NaCl. Spectra were collected for both wet (40% water by weight) and air-dried Fe oxide suspensions using a Bio-Rad FTS-175C immediately after mixing with KBr at a solid to KBr ratio of 5 to 95 mg

View larger version (40K): [in a new window]   Fig. 11 Diffuse reflectance infrared Fourier transform (DRIFT) spectra of goethite reacted at pH 5.0 with (a) 0.10 M Na2SeO4 + 1.0 M NaCl, and (b) 1.0 M NaCl alone, and the difference spectrum (a–b). The solid to KBr ratio was 5 to 95 mg. The BET N2 surface area of goethite was 21.8 m2 g-1

View larger version (28K): [in a new window]   Fig. 12 Attenuated total reflectance–Fourier transform infrared (ATR–FTIR) difference spectra of am-Fe(OH)3 equilibrated at pH 5.0 with (a) 0.5 M Na2SeO3 + 1.0 M NaCl, and (b) 1.0 M NaCl alone. The subtracted reference spectra were the supernatant solutions. The initial solid concentration was 200 g L-1 before centrifugation and the solid concentration in the ATR reservoir was 1000 g L-1. The interfacial Se(IV) spectrum was presented as (a–b)

View larger version (29K): [in a new window]   Fig. 13 Diffuse reflectance infrared Fourier transform (DRIFT) difference spectra of sorbed selenite on am-Fe(OH)3 reacted with 0.05 M Na2SeO3 + 1.0 M NaCl at pH 5.0. The reference spectrum was the am-Fe(OH)3 equilibrated with 1.0 M NaCl

View larger version (32K): [in a new window]   Fig. 14 Diffuse reflectance infrared Fourier transform (DRIFT) difference spectra of sorbed selenite on am-Fe(OH)3 at pH 8.0: (a) analytical grade Na2SeO3 and (b) am-Fe(OH)3 reacted with 0.05 M Na2SeO3 + 1.0 M NaCl. The reference spectrum for (b) was the am-Fe(OH)3 equilibrated with 1.0 M NaCl