PMID- 26280799
OWN - NLM
STAT- MEDLINE
DCOM- 20160425
LR  - 20181202
IS  - 1520-5851 (Electronic)
IS  - 0013-936X (Linking)
VI  - 49
IP  - 18
DP  - 2015 Sep 15
TI  - Aggregation and Stability of Reduced Graphene Oxide: Complex Roles of Divalent 
      Cations, pH, and Natural Organic Matter.
PG  - 10886-93
LID - 10.1021/acs.est.5b01866 [doi]
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 Ca(2+) 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 Ca(2+) ions on rGO stability. Critical 
      coagulation concentrations (CCC) of GO, rGO-1h, and rGO-2h were determined to be 
       approximately  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 (Ca(2+), Mg(2+)), 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.
FAU - Chowdhury, Indranil
AU  - Chowdhury I
AD  - Department of Civil and Environmental Engineering, Washington State University , 
      Pullman, Washington 99164, United States.
FAU - Mansukhani, Nikhita D
AU  - Mansukhani ND
AD  - Departments of Materials Science and Engineering, Chemistry, and Medicine, 
      Northwestern University , Evanston, Illinois 60208, United States.
FAU - Guiney, Linda M
AU  - Guiney LM
AD  - Departments of Materials Science and Engineering, Chemistry, and Medicine, 
      Northwestern University , Evanston, Illinois 60208, United States.
FAU - Hersam, Mark C
AU  - Hersam MC
AD  - Departments of Materials Science and Engineering, Chemistry, and Medicine, 
      Northwestern University , Evanston, Illinois 60208, United States.
FAU - Bouchard, Dermont
AU  - Bouchard D
AD  - National Exposure Research Laboratory, Ecosystems Research Division, United 
      States Environmental Protection Agency , Athens, Georgia 30605, United States.
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
DEP - 20150901
PL  - United States
TA  - Environ Sci Technol
JT  - Environmental science & technology
JID - 0213155
RN  - 0 (Cations, Divalent)
RN  - 0 (Oxides)
RN  - 0 (Water Pollutants, Chemical)
RN  - 059QF0KO0R (Water)
RN  - 451W47IQ8X (Sodium Chloride)
RN  - 7782-42-5 (Graphite)
SB  - IM
MH  - Adsorption
MH  - Cations, Divalent/chemistry
MH  - Graphite/*chemistry
MH  - Hydrogen-Ion Concentration
MH  - Nanostructures/*chemistry
MH  - Osmolar Concentration
MH  - Oxidation-Reduction
MH  - Oxides/chemistry
MH  - Sodium Chloride
MH  - Water
MH  - Water Pollutants, Chemical
EDAT- 2015/08/19 06:00
MHDA- 2016/04/26 06:00
CRDT- 2015/08/18 06:00
PHST- 2015/08/18 06:00 [entrez]
PHST- 2015/08/19 06:00 [pubmed]
PHST- 2016/04/26 06:00 [medline]
AID - 10.1021/acs.est.5b01866 [doi]
PST - ppublish
SO  - Environ Sci Technol. 2015 Sep 15;49(18):10886-93. doi: 10.1021/acs.est.5b01866. 
      Epub 2015 Sep 1.