PMID- 19031888
OWN - NLM
STAT- MEDLINE
DCOM- 20090114
LR  - 20190715
IS  - 0013-936X (Print)
IS  - 0013-936X (Linking)
VI  - 42
IP  - 21
DP  - 2008 Nov 1
TI  - Aggregation kinetics of multiwalled carbon nanotubes in aquatic systems: 
      measurements and environmental implications.
PG  - 7963-9
AB  - The initial aggregation kinetics of multiwalled carbon nanotubes (MWNTs) were 
      examined through time-resolved dynamic light scattering. Aggregation of MWNTs was 
      evaluated by varying solution pH and the concentration of monovalent (NaCl) and 
      divalent (CaCl2 and MgCl2) salts. Suwannee River humic acid (SRHA) was used to 
      study the effect of background natural organic matter on MWNT aggregation 
      kinetics, Increasing salt concentration and addition of divalent calcium and 
      magnesium ions induced MWNT aggregation by suppressing electrostatic repulsion, 
      similar to observations with aquatic colloidal particles. The critical 
      coagulation concentration (CCC) values for MWNTs were estimated as 25 mM NaCI, 
      2.6 mM CaCl2, and 1.5 mM MgCl2. An increase in solution pH from acidic (pH 3) to 
      basic (pH 11) conditions resulted in a substantial (over 2 orders of magnitude) 
      decrease in MWNT aggregation kinetics, suggesting the presence of ionizable 
      functional groups on the MWNT carbon scaffold. The presence of humic acid in 
      solution markedly enhanced the colloidal stability of MWNTs, reducing the 
      aggregation rate by nearly 2 orders of magnitude. The enhanced MWNT stability in 
      the presence of humic acid is attributable to steric repulsion imparted by 
      adsorbed humic acid macromolecules. Our results suggest that MWNTs are relatively 
      stable at solution pH and electrolyte conditions typical of aquatic environments.
FAU - Saleh, Navid B
AU  - Saleh NB
AD  - Department of Chemical Engineering, Yale University, New Haven, Connecticut 
      06520-8286, USA.
FAU - Pfefferle, Lisa D
AU  - Pfefferle LD
FAU - Elimelech, Menachem
AU  - Elimelech M
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - United States
TA  - Environ Sci Technol
JT  - Environmental science & technology
JID - 0213155
RN  - 0 (Cations, Divalent)
RN  - 0 (Cations, Monovalent)
RN  - 0 (Electrolytes)
RN  - 0 (Humic Substances)
RN  - 0 (Nanotubes, Carbon)
RN  - 0 (Solutions)
RN  - 451W47IQ8X (Sodium Chloride)
SB  - IM
MH  - Cations, Divalent/chemistry
MH  - Cations, Monovalent/chemistry
MH  - Electrolytes/chemistry
MH  - Electrophoresis
MH  - *Environment
MH  - Humic Substances
MH  - Hydrogen-Ion Concentration/drug effects
MH  - Kinetics
MH  - Motion
MH  - Nanotubes, Carbon/*chemistry/ultrastructure
MH  - Rivers/*chemistry
MH  - Sodium Chloride/chemistry
MH  - Solutions
EDAT- 2008/11/27 09:00
MHDA- 2009/01/15 09:00
CRDT- 2008/11/27 09:00
PHST- 2008/11/27 09:00 [pubmed]
PHST- 2009/01/15 09:00 [medline]
PHST- 2008/11/27 09:00 [entrez]
AID - 10.1021/es801251c [doi]
PST - ppublish
SO  - Environ Sci Technol. 2008 Nov 1;42(21):7963-9. doi: 10.1021/es801251c.