Aggregation and Stability of Reduced Graphene Oxide: Complex Roles of Divalent Cations, pH, and Natural Organic Matter

Indranil Chowdhury, Nikhita D. Mansukhani, Linda M. Guiney, Mark C Hersam, Dermont Bouchard

Research output: Contribution to journalArticle

108 Citations (Scopus)

Abstract

The aggregation and stability of graphene oxide (GO) and three successively reduced GO (rGO) nanomaterials were investigated. Reduced GO species were partially reduced GO (rGO-1h), intermediately reduced GO (rGO-2h), and fully reduced GO (rGO-5h). Specifically, influence of pH, ionic strength, ion valence, and presence of natural organic matter (NOM) were studied. Results show that stability of GO in water decreases with successive reduction of functional groups, with pH having the greatest influence on rGO stability. Stability is also dependent on ion valence and the concentration of surface functional groups. While pH did not noticeably affect stability of GO in the presence of 10 mM NaCl, adding 0.1 mM CaCl2 reduced stability of GO with increased pH. This is due to adsorption of Ca2+ ions on the surface functional groups of GO which reduces the surface charge of GO. As the concentration of rGO functional groups decreased, so did the influence of Ca2+ ions on rGO stability. Critical coagulation concentrations (CCC) of GO, rGO-1h, and rGO-2h were determined to be '200 mM, 35 mM, and 30 mM NaCl, respectively. In the presence of CaCl2, CCC values of GO and rGO are quite similar, however. Long-term studies show that a significant amount of rGO-1h and rGO-2h remain stable in Call's Creek surface water, while effluent wastewater readily destabilizes rGO. In the presence NOM and divalent cations (Ca2+, Mg2+), GO aggregates settle from suspension due to GO functional group bridging with NOM and divalent ions. However, rGO-1h and rGO-2h remain suspended due to their lower functional group concentration and resultant reduced NOM-divalent cation bridging. Overall, pH, divalent cations, and NOM can play complex roles in the fate of rGO and GO.

Original languageEnglish
Pages (from-to)10886-10893
Number of pages8
JournalEnvironmental Science and Technology
Volume49
Issue number18
DOIs
Publication statusPublished - Sep 15 2015

Fingerprint

Graphite
Divalent Cations
Biological materials
Oxides
Agglomeration
cation
oxide
organic matter
Functional groups
functional group
Ions
ion
Coagulation
coagulation
Surface charge
Ionic strength
Surface waters
Nanostructured materials

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

Cite this

Aggregation and Stability of Reduced Graphene Oxide : Complex Roles of Divalent Cations, pH, and Natural Organic Matter. / Chowdhury, Indranil; Mansukhani, Nikhita D.; Guiney, Linda M.; Hersam, Mark C; Bouchard, Dermont.

In: Environmental Science and Technology, Vol. 49, No. 18, 15.09.2015, p. 10886-10893.

Research output: Contribution to journalArticle

Chowdhury, Indranil ; Mansukhani, Nikhita D. ; Guiney, Linda M. ; Hersam, Mark C ; Bouchard, Dermont. / Aggregation and Stability of Reduced Graphene Oxide : Complex Roles of Divalent Cations, pH, and Natural Organic Matter. In: Environmental Science and Technology. 2015 ; Vol. 49, No. 18. pp. 10886-10893.
@article{a5b615559a10477ea71c7025b89c872c,
title = "Aggregation and Stability of Reduced Graphene Oxide: Complex Roles of Divalent Cations, pH, and Natural Organic Matter",
abstract = "The aggregation and stability of graphene oxide (GO) and three successively reduced GO (rGO) nanomaterials were investigated. Reduced GO species were partially reduced GO (rGO-1h), intermediately reduced GO (rGO-2h), and fully reduced GO (rGO-5h). Specifically, influence of pH, ionic strength, ion valence, and presence of natural organic matter (NOM) were studied. Results show that stability of GO in water decreases with successive reduction of functional groups, with pH having the greatest influence on rGO stability. Stability is also dependent on ion valence and the concentration of surface functional groups. While pH did not noticeably affect stability of GO in the presence of 10 mM NaCl, adding 0.1 mM CaCl2 reduced stability of GO with increased pH. This is due to adsorption of Ca2+ ions on the surface functional groups of GO which reduces the surface charge of GO. As the concentration of rGO functional groups decreased, so did the influence of Ca2+ ions on rGO stability. Critical coagulation concentrations (CCC) of GO, rGO-1h, and rGO-2h were determined to be '200 mM, 35 mM, and 30 mM NaCl, respectively. In the presence of CaCl2, CCC values of GO and rGO are quite similar, however. Long-term studies show that a significant amount of rGO-1h and rGO-2h remain stable in Call's Creek surface water, while effluent wastewater readily destabilizes rGO. In the presence NOM and divalent cations (Ca2+, Mg2+), GO aggregates settle from suspension due to GO functional group bridging with NOM and divalent ions. However, rGO-1h and rGO-2h remain suspended due to their lower functional group concentration and resultant reduced NOM-divalent cation bridging. Overall, pH, divalent cations, and NOM can play complex roles in the fate of rGO and GO.",
author = "Indranil Chowdhury and Mansukhani, {Nikhita D.} and Guiney, {Linda M.} and Hersam, {Mark C} and Dermont Bouchard",
year = "2015",
month = "9",
day = "15",
doi = "10.1021/acs.est.5b01866",
language = "English",
volume = "49",
pages = "10886--10893",
journal = "Environmental Science & Technology",
issn = "0013-936X",
publisher = "American Chemical Society",
number = "18",

}

TY - JOUR

T1 - Aggregation and Stability of Reduced Graphene Oxide

T2 - Complex Roles of Divalent Cations, pH, and Natural Organic Matter

AU - Chowdhury, Indranil

AU - Mansukhani, Nikhita D.

AU - Guiney, Linda M.

AU - Hersam, Mark C

AU - Bouchard, Dermont

PY - 2015/9/15

Y1 - 2015/9/15

N2 - The aggregation and stability of graphene oxide (GO) and three successively reduced GO (rGO) nanomaterials were investigated. Reduced GO species were partially reduced GO (rGO-1h), intermediately reduced GO (rGO-2h), and fully reduced GO (rGO-5h). Specifically, influence of pH, ionic strength, ion valence, and presence of natural organic matter (NOM) were studied. Results show that stability of GO in water decreases with successive reduction of functional groups, with pH having the greatest influence on rGO stability. Stability is also dependent on ion valence and the concentration of surface functional groups. While pH did not noticeably affect stability of GO in the presence of 10 mM NaCl, adding 0.1 mM CaCl2 reduced stability of GO with increased pH. This is due to adsorption of Ca2+ ions on the surface functional groups of GO which reduces the surface charge of GO. As the concentration of rGO functional groups decreased, so did the influence of Ca2+ ions on rGO stability. Critical coagulation concentrations (CCC) of GO, rGO-1h, and rGO-2h were determined to be '200 mM, 35 mM, and 30 mM NaCl, respectively. In the presence of CaCl2, CCC values of GO and rGO are quite similar, however. Long-term studies show that a significant amount of rGO-1h and rGO-2h remain stable in Call's Creek surface water, while effluent wastewater readily destabilizes rGO. In the presence NOM and divalent cations (Ca2+, Mg2+), GO aggregates settle from suspension due to GO functional group bridging with NOM and divalent ions. However, rGO-1h and rGO-2h remain suspended due to their lower functional group concentration and resultant reduced NOM-divalent cation bridging. Overall, pH, divalent cations, and NOM can play complex roles in the fate of rGO and GO.

AB - The aggregation and stability of graphene oxide (GO) and three successively reduced GO (rGO) nanomaterials were investigated. Reduced GO species were partially reduced GO (rGO-1h), intermediately reduced GO (rGO-2h), and fully reduced GO (rGO-5h). Specifically, influence of pH, ionic strength, ion valence, and presence of natural organic matter (NOM) were studied. Results show that stability of GO in water decreases with successive reduction of functional groups, with pH having the greatest influence on rGO stability. Stability is also dependent on ion valence and the concentration of surface functional groups. While pH did not noticeably affect stability of GO in the presence of 10 mM NaCl, adding 0.1 mM CaCl2 reduced stability of GO with increased pH. This is due to adsorption of Ca2+ ions on the surface functional groups of GO which reduces the surface charge of GO. As the concentration of rGO functional groups decreased, so did the influence of Ca2+ ions on rGO stability. Critical coagulation concentrations (CCC) of GO, rGO-1h, and rGO-2h were determined to be '200 mM, 35 mM, and 30 mM NaCl, respectively. In the presence of CaCl2, CCC values of GO and rGO are quite similar, however. Long-term studies show that a significant amount of rGO-1h and rGO-2h remain stable in Call's Creek surface water, while effluent wastewater readily destabilizes rGO. In the presence NOM and divalent cations (Ca2+, Mg2+), GO aggregates settle from suspension due to GO functional group bridging with NOM and divalent ions. However, rGO-1h and rGO-2h remain suspended due to their lower functional group concentration and resultant reduced NOM-divalent cation bridging. Overall, pH, divalent cations, and NOM can play complex roles in the fate of rGO and GO.

UR - http://www.scopus.com/inward/record.url?scp=84937860679&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84937860679&partnerID=8YFLogxK

U2 - 10.1021/acs.est.5b01866

DO - 10.1021/acs.est.5b01866

M3 - Article

C2 - 26280799

AN - SCOPUS:84937860679

VL - 49

SP - 10886

EP - 10893

JO - Environmental Science & Technology

JF - Environmental Science & Technology

SN - 0013-936X

IS - 18

ER -