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Title: Mechanisms of Chromate Adsorption on Boehmite

Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0304-3894
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Hazardous Materials; Journal Volume: 281
Country of Publication:
United States

Citation Formats

Johnston, C, and Chrysochoou, M. Mechanisms of Chromate Adsorption on Boehmite. United States: N. p., 2015. Web. doi:10.1016/j.jhazmat.2014.09.050.
Johnston, C, & Chrysochoou, M. Mechanisms of Chromate Adsorption on Boehmite. United States. doi:10.1016/j.jhazmat.2014.09.050.
Johnston, C, and Chrysochoou, M. 2015. "Mechanisms of Chromate Adsorption on Boehmite". United States. doi:10.1016/j.jhazmat.2014.09.050.
title = {Mechanisms of Chromate Adsorption on Boehmite},
author = {Johnston, C and Chrysochoou, M},
abstractNote = {},
doi = {10.1016/j.jhazmat.2014.09.050},
journal = {Journal of Hazardous Materials},
number = ,
volume = 281,
place = {United States},
year = 2015,
month = 1
  • Reductive precipitation of hexavalent chromium (Cr(VI)) with magnetite is a well-known Cr(VI) remediation method to improve water quality. The rapid (< a few hr) reduction of soluble Cr(VI) to insoluble Cr(III) species by Fe(II) in magnetite has been the primary focus of the Cr(VI) removal process in the past. However, the contribution of simultaneous Cr(VI) adsorption processes in aged magnetite has been largely ignored, leaving uncertainties in evaluating the application of in situ Cr remediation technologies for aqueous systems. In this study, effects of common groundwater ions (i.e., nitrate and sulfate) on Cr(VI) sorption to magnetite were investigated using batchmore » geochemical experiments in conjunction with X-ray absorption spectroscopy. As a result, in both nitrate and sulfate electrolytes, batch sorption experiments showed that Cr(VI) sorption decreases with increasing pH from 4 to 8. In this pH range, Cr(VI) sorption decreased with increasing ionic strength of sulfate from 0.01 to 0.1 M whereas nitrate concentrations did not alter the Cr(VI) sorption behavior. This indicates the background electrolyte specific Cr(VI) sorption process in magnetite. Under the same ionic strength, Cr(VI) removal in sulfate containing solutions was greater than that in nitrate solutions. This is because the oxidation of Fe(II) by nitrate is more thermodynamically favorable than by sulfate, leaving less reduction capacity of magnetite to reduce Cr(VI) in the nitrate media. X-ray absorption spectroscopy analysis supports the macroscopic evidence that more than 75 % of total Cr on the magnetite surfaces was adsorbed Cr(VI) species after 48 h. In conclusion, this experimental geochemical study showed that the adsorption process of Cr(VI) anions was as important as the reductive precipitation of Cr(III) in describing the removal of Cr(VI) by magnetite, and these interfacial adsorption processes could be impacted by common groundwater ions like sulfate and nitrate. The results of this study highlight new information about the large quantity of adsorbed Cr(VI) surface complexes at the magnetite-water interface. It has implications for predicting the long-term stability of Cr at the magnetite-water interface.« less
  • This work is concerned with the adsorption of o-phthalate (1,2-benzenedicarboxylate) at the water-metal (hydr)oxide interface. Previously published infrared spectroscopic, potentiometric, and adsorption data characterizing the boehmite ({gamma}-AlOOH) system are compared with new data collected for o-phthalate adsorption on aged {gamma}-Al{sub 2}O{sub 3} and goethite ({alpha}-FeOOH). The study focuses on identifying bonding mechanisms, stoichiometries, and stabilities of the formed complexes, and comparing these among the three systems. Furthermore, the effects of ionic strength and composition of the ionic medium are investigated. The infrared spectroscopic data provided direct, molecular-level evidence for the existence of two dominating surface complexes on all three solids.more » One was shown to be a deprotonated outer-sphere species and the other was n inner-sphere surface complex. The inner-sphere complexes on the three solids were structurally related, and they were tentatively assigned to a mononuclear, chelating structure involving both carboxylate groups. The outer-spheres complexes were shown to increase in relative importance at high pH and low ionic strengths, while low pH and high ionic strengths favored the inner-sphere complexes. The information gained from the infrared spectroscopic investigations was used as qualitative input in the formulation of the surface complexation models. New models, based on the extended constant capacitance approach, were presented for the o-phthalate/aged {gamma}-Al{sub 2}O{sub 3} and o-phthalate/goethite systems.« less
  • No abstract prepared.