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Title: Adsorption Study of Al 3+, Cr 3+, and Mn 2+ onto Quartz and Corundum using Flow Microcalorimetry, Quartz Crystal Microbalance, and Density Functional Theory

Abstract

The adsorption of aqueous ions onto natural mineral surfaces controls numerous mineral–water interactions and is governed by, among other numerous factors, ion dehydration and hydrolysis. This work explored the extent to which dehydration and hydrolysis affect the adsorption of three metal cations, Al 3+, Cr 3+, and Mn 2+, onto quartz (SiO2) and corundum (Al 2O 3) surfaces at pH 3.8 through the integration of flow microcalorimetry (FMC), quartz crystal microbalance with dissipation (QCM-D) measurements and density functional theory (DFT) calculations. At pH 3.8, negligible amounts of Mn 2+ and Al 3+ are hydrolyzed, while 78% of Cr 3+ exist in hydrolyzed species. QCM-D and FMC measurements showed that Al 3+ and Cr 3+ adsorb to both surfaces, while Mn 2+ adsorbed only to Al 2O 3. DFT bond energy calculations confirmed the favorable bonding between the mineral surfaces and Al 3+ and Cr 3+, and that Mn 2+ adsorption onto SiO 2 was unfavorable. Furthermore, FMC showed that on both surfaces, the adsorption of Al 3+ was endothermic and reversible, while that of Cr 3+ was exothermic and partially irreversible. Through the integration of experimental and computational methods, this work suggested that the reversible adsorption of unhydrolyzed cations (Mnmore » 2+ and Al 3+) occurred through weak electrostatic interactions. The large energy cost required to dehydrate unhydrolyzed cations resulted in an endothermic adsorption process. Meanwhile, hydrolyzed Cr 3+ species can adsorb on quartz and corundum through covalent-bond formation, and thus, their adsorption was partially irreversible. Furthermore, the hydrolysis of Cr 3+ lowered the dehydration energy during adsorption, resulting in an exothermic adsorption. By using bond energies as a guide to indicate the possibility of thermodynamically favored adsorption, there was a strong agreement between the DFT and experimental techniques. The findings presented here contribute to understanding and predicting various mineral–water interfacial processes in the natural environment.« less

Authors:
 [1];  [2]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]
  1. Georgia State Univ., Atlanta, GA (United States). Dept. of Chemistry
  2. Univ. of Houston, TX (United States). Dept. of Civil and Environmental Engineering
  3. Univ. of Texas at El Paso, TX (United States). Dept. of Geological Sciences
  4. Georgia State Univ., Atlanta, GA (United States). Dept. of Chemistry and Dept. of Geosciences
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1606776
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ACS Earth and Space Chemistry
Additional Journal Information:
Journal Volume: 3; Journal Issue: 3; Journal ID: ISSN 2472-3452
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; flow microcalorimetry (FMC); quartz crystal microbalance with dissipation (QCM-D); density functional theory (DFT) calculations; endothermic and exothermic; reversibility; ion hydrolysis; ion dehydration; bond energy

Citation Formats

Allen, Nicholas, Dai, Chong, Hu, Yandi, Kubicki, James D., and Kabengi, Nadine. Adsorption Study of Al3+, Cr3+, and Mn2+ onto Quartz and Corundum using Flow Microcalorimetry, Quartz Crystal Microbalance, and Density Functional Theory. United States: N. p., 2019. Web. doi:10.1021/acsearthspacechem.8b00148.
Allen, Nicholas, Dai, Chong, Hu, Yandi, Kubicki, James D., & Kabengi, Nadine. Adsorption Study of Al3+, Cr3+, and Mn2+ onto Quartz and Corundum using Flow Microcalorimetry, Quartz Crystal Microbalance, and Density Functional Theory. United States. doi:10.1021/acsearthspacechem.8b00148.
Allen, Nicholas, Dai, Chong, Hu, Yandi, Kubicki, James D., and Kabengi, Nadine. Wed . "Adsorption Study of Al3+, Cr3+, and Mn2+ onto Quartz and Corundum using Flow Microcalorimetry, Quartz Crystal Microbalance, and Density Functional Theory". United States. doi:10.1021/acsearthspacechem.8b00148. https://www.osti.gov/servlets/purl/1606776.
@article{osti_1606776,
title = {Adsorption Study of Al3+, Cr3+, and Mn2+ onto Quartz and Corundum using Flow Microcalorimetry, Quartz Crystal Microbalance, and Density Functional Theory},
author = {Allen, Nicholas and Dai, Chong and Hu, Yandi and Kubicki, James D. and Kabengi, Nadine},
abstractNote = {The adsorption of aqueous ions onto natural mineral surfaces controls numerous mineral–water interactions and is governed by, among other numerous factors, ion dehydration and hydrolysis. This work explored the extent to which dehydration and hydrolysis affect the adsorption of three metal cations, Al3+, Cr3+, and Mn2+, onto quartz (SiO2) and corundum (Al2O3) surfaces at pH 3.8 through the integration of flow microcalorimetry (FMC), quartz crystal microbalance with dissipation (QCM-D) measurements and density functional theory (DFT) calculations. At pH 3.8, negligible amounts of Mn2+ and Al3+ are hydrolyzed, while 78% of Cr3+ exist in hydrolyzed species. QCM-D and FMC measurements showed that Al3+ and Cr3+ adsorb to both surfaces, while Mn2+ adsorbed only to Al2O3. DFT bond energy calculations confirmed the favorable bonding between the mineral surfaces and Al3+ and Cr3+, and that Mn2+ adsorption onto SiO2 was unfavorable. Furthermore, FMC showed that on both surfaces, the adsorption of Al3+ was endothermic and reversible, while that of Cr3+ was exothermic and partially irreversible. Through the integration of experimental and computational methods, this work suggested that the reversible adsorption of unhydrolyzed cations (Mn2+ and Al3+) occurred through weak electrostatic interactions. The large energy cost required to dehydrate unhydrolyzed cations resulted in an endothermic adsorption process. Meanwhile, hydrolyzed Cr3+ species can adsorb on quartz and corundum through covalent-bond formation, and thus, their adsorption was partially irreversible. Furthermore, the hydrolysis of Cr3+ lowered the dehydration energy during adsorption, resulting in an exothermic adsorption. By using bond energies as a guide to indicate the possibility of thermodynamically favored adsorption, there was a strong agreement between the DFT and experimental techniques. The findings presented here contribute to understanding and predicting various mineral–water interfacial processes in the natural environment.},
doi = {10.1021/acsearthspacechem.8b00148},
journal = {ACS Earth and Space Chemistry},
issn = {2472-3452},
number = 3,
volume = 3,
place = {United States},
year = {2019},
month = {1}
}

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