A short review on regulation of stability of aqueous suspensions of carbon nanotubes
This review analyses the authors’ recent and related works on electrokinetic properties and colloidal stability of aqueous suspension of multiwalled carbon nanotubes (CNTs) in the presence of surfactants and nanoparticles. Selected adsorptive properties of carbon nanotubes are also considered. The...
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Chuiko Institute of Surface Chemistry of NAS of Ukraine
2020-02-01
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| Series: | Хімія, фізика та технологія поверхні |
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| Online Access: | https://cpts.com.ua/index.php/cpts/article/view/537 |
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| author | M. V. Manilo N. I. Lebovka S. Barany |
| author_facet | M. V. Manilo N. I. Lebovka S. Barany |
| author_sort | M. V. Manilo |
| collection | DOAJ |
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This review analyses the authors’ recent and related works on electrokinetic properties and colloidal stability of aqueous suspension of multiwalled carbon nanotubes (CNTs) in the presence of surfactants and nanoparticles. Selected adsorptive properties of carbon nanotubes are also considered.
The applicability of classical theories of electrophoresis for description of electrophoretic mobility of carbon nanotubes is discussed. Examples on the ?-potential of CNTs in aqueous suspensions as a function of pH and concentration of electrolytes (KCl, CaCl2 and AlCl3) are given. Additions of cetyltrimethylammonium bromide (CTAB) cationic surfactant below the critical micelle formation concentration (CMC) values give a reduction and then an overcharging the CNT surface because of accumulation of the surfactant ions in the Stern layer. At concentrations above CMC the substantial drop in ? is observed. It is due to the shift of the shear plane toward solution as a result of formation of hemi-micelles on the surface. An increase in the mass ratio of artificial mineral Laponite (Lap) in suspension (X) from 0 to 0.4 results in a monotonic decrease of the ?-potential of CNT + Lap hybrids with reaching its plateau value ? –32 mV at X ? 0.4 that corresponds to the ? of “pure” Lap platelets. This evidences the high surface coverage of nanotubes surface with Lap at X ? 0.4.
The major methods to improve the dispersibility of carbon nanotubes, their colloidal stability and adsorptive properties are briefly discussed, namely: stabilization in mixtures of water and organic solvents; functionalization by chemical treatment; stabilization by additives of surfactants or polymers and hybridization by addition of supplementary stabilizing nanoparticles. CNTs can be significantly debundled in “good” solvents, such as 1-cyclohexyl-2-pyrrolidone, N,N-dimethylformamide, or N-methyl-2-pyrrolidone. It is demonstrated that the dispersibility of CNTs is a complex function of the type of surfactant, its concentration and the surfactant/CNTs ratio. The optimum concentration of CTAB to achieve homogeneous aqueous dispersion of carbon nanotubes was identified to be near the CMC. Additions of CTAB significantly modify the size distribution of CNTs and a sharp transition from small primary aggregates to large secondary aggregates at concentrations above CMC is observed. At optimal concentration of Lap the nanotube particles get well stabilized, and a stepwise increase of sedimentation stability is observed.
We have shown also that CNT + Lap hybrids can be effectively used for removal of methylene blue dye from aqueous systems. The kinetics and mechanisms of adsorption are elucidated.
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| format | Article |
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| institution | Kabale University |
| issn | 2079-1704 2518-1238 |
| language | English |
| publishDate | 2020-02-01 |
| publisher | Chuiko Institute of Surface Chemistry of NAS of Ukraine |
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| series | Хімія, фізика та технологія поверхні |
| spelling | doaj-art-16a6b3ab89b94cedaa3ca7cd54b1b1102025-08-20T03:31:19ZengChuiko Institute of Surface Chemistry of NAS of UkraineХімія, фізика та технологія поверхні2079-17042518-12382020-02-0111110.15407/hftp11.01.144A short review on regulation of stability of aqueous suspensions of carbon nanotubesM. V. Manilo0N. I. Lebovka1S. Barany2F.D. Ovcharenko Institute of Biocolloidal Chemistry of National Academy of Sciences of Ukraine / University of Miskolc, Research Institute of Applied Earth Sciences and MTA-ME Materials Science Research GroupF.D. Ovcharenko Institute of Biocolloidal Chemistry of National Academy of Sciences of UkraineUniversity of Miskolc, Research Institute of Applied Earth Sciences and MTA-ME Materials Science Research Group This review analyses the authors’ recent and related works on electrokinetic properties and colloidal stability of aqueous suspension of multiwalled carbon nanotubes (CNTs) in the presence of surfactants and nanoparticles. Selected adsorptive properties of carbon nanotubes are also considered. The applicability of classical theories of electrophoresis for description of electrophoretic mobility of carbon nanotubes is discussed. Examples on the ?-potential of CNTs in aqueous suspensions as a function of pH and concentration of electrolytes (KCl, CaCl2 and AlCl3) are given. Additions of cetyltrimethylammonium bromide (CTAB) cationic surfactant below the critical micelle formation concentration (CMC) values give a reduction and then an overcharging the CNT surface because of accumulation of the surfactant ions in the Stern layer. At concentrations above CMC the substantial drop in ? is observed. It is due to the shift of the shear plane toward solution as a result of formation of hemi-micelles on the surface. An increase in the mass ratio of artificial mineral Laponite (Lap) in suspension (X) from 0 to 0.4 results in a monotonic decrease of the ?-potential of CNT + Lap hybrids with reaching its plateau value ? –32 mV at X ? 0.4 that corresponds to the ? of “pure” Lap platelets. This evidences the high surface coverage of nanotubes surface with Lap at X ? 0.4. The major methods to improve the dispersibility of carbon nanotubes, their colloidal stability and adsorptive properties are briefly discussed, namely: stabilization in mixtures of water and organic solvents; functionalization by chemical treatment; stabilization by additives of surfactants or polymers and hybridization by addition of supplementary stabilizing nanoparticles. CNTs can be significantly debundled in “good” solvents, such as 1-cyclohexyl-2-pyrrolidone, N,N-dimethylformamide, or N-methyl-2-pyrrolidone. It is demonstrated that the dispersibility of CNTs is a complex function of the type of surfactant, its concentration and the surfactant/CNTs ratio. The optimum concentration of CTAB to achieve homogeneous aqueous dispersion of carbon nanotubes was identified to be near the CMC. Additions of CTAB significantly modify the size distribution of CNTs and a sharp transition from small primary aggregates to large secondary aggregates at concentrations above CMC is observed. At optimal concentration of Lap the nanotube particles get well stabilized, and a stepwise increase of sedimentation stability is observed. We have shown also that CNT + Lap hybrids can be effectively used for removal of methylene blue dye from aqueous systems. The kinetics and mechanisms of adsorption are elucidated. https://cpts.com.ua/index.php/cpts/article/view/537carbon nanotubesaqueous suspensioncolloidal stabilityzeta potentialsurfactantshybrids |
| spellingShingle | M. V. Manilo N. I. Lebovka S. Barany A short review on regulation of stability of aqueous suspensions of carbon nanotubes Хімія, фізика та технологія поверхні carbon nanotubes aqueous suspension colloidal stability zeta potential surfactants hybrids |
| title | A short review on regulation of stability of aqueous suspensions of carbon nanotubes |
| title_full | A short review on regulation of stability of aqueous suspensions of carbon nanotubes |
| title_fullStr | A short review on regulation of stability of aqueous suspensions of carbon nanotubes |
| title_full_unstemmed | A short review on regulation of stability of aqueous suspensions of carbon nanotubes |
| title_short | A short review on regulation of stability of aqueous suspensions of carbon nanotubes |
| title_sort | short review on regulation of stability of aqueous suspensions of carbon nanotubes |
| topic | carbon nanotubes aqueous suspension colloidal stability zeta potential surfactants hybrids |
| url | https://cpts.com.ua/index.php/cpts/article/view/537 |
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