Adsorption of Gold(I) and Gold(III) Using Multiwalled Carbon Nanotubes
Carbon nanotubes are materials that have been investigated for diverse applications including the adsorption of metals. However, scarce literature has described their behavior in the case of the adsorption of precious metals. Thus, this work reports the efficient adsorption of gold from cyanide or c...
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doaj-187d7d0128734c85893809e49b72f2622020-11-25T00:37:13ZengMDPI AGApplied Sciences2076-34172018-11-01811226410.3390/app8112264app8112264Adsorption of Gold(I) and Gold(III) Using Multiwalled Carbon NanotubesFrancisco Jose Alguacil0Centro Nacional de Investigaciones Metalurgicas (CSIC), Avda. Gregorio del Amo 8, 28040 Madrid, SpainCarbon nanotubes are materials that have been investigated for diverse applications including the adsorption of metals. However, scarce literature has described their behavior in the case of the adsorption of precious metals. Thus, this work reports the efficient adsorption of gold from cyanide or chloride media on multiwalled carbon nanotubes (MWCNTs). In a cyanide medium, gold was adsorbed from alkaline pH values decreasing the adsorption as the pH values were increased to more acidic values. In a chloride medium, the MWCNTs were able to load the precious metal and an increased HCl concentration (0.1⁻10 M), in the aqueous solution, had no effect on the gold uptake onto the nanotubes. From both aqueous media, the metal adsorption was well represented by the pseudo-second order kinetic model. In the cyanide medium, the film-diffusion controlled process best fitted the rate law governing the adsorption of gold onto the nanotubes, whereas in the chloride medium, the adsorption of the metal onto the nanotubes is best represented, both at 20 °C and 60 °C, by the particle-diffusion controlled process. With respect to the elution step, in cyanide medium gold loaded onto the nanotubes can be eluted with acidic thiourea solutions, whereas in the chloride medium, and due to that the adsorption process involved the precipitation of zero valent gold onto the multiwalled carbon nanotubes, the elution has been considered as a leaching step with aqua regia. From the eluates, dissolved gold can be conveniently precipitated as zero valent gold nanoparticles.https://www.mdpi.com/2076-3417/8/11/2264multiwalled carbon nanotubesgold(I)gold(III)adsorptionelutiongold nanoparticles |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Francisco Jose Alguacil |
spellingShingle |
Francisco Jose Alguacil Adsorption of Gold(I) and Gold(III) Using Multiwalled Carbon Nanotubes Applied Sciences multiwalled carbon nanotubes gold(I) gold(III) adsorption elution gold nanoparticles |
author_facet |
Francisco Jose Alguacil |
author_sort |
Francisco Jose Alguacil |
title |
Adsorption of Gold(I) and Gold(III) Using Multiwalled Carbon Nanotubes |
title_short |
Adsorption of Gold(I) and Gold(III) Using Multiwalled Carbon Nanotubes |
title_full |
Adsorption of Gold(I) and Gold(III) Using Multiwalled Carbon Nanotubes |
title_fullStr |
Adsorption of Gold(I) and Gold(III) Using Multiwalled Carbon Nanotubes |
title_full_unstemmed |
Adsorption of Gold(I) and Gold(III) Using Multiwalled Carbon Nanotubes |
title_sort |
adsorption of gold(i) and gold(iii) using multiwalled carbon nanotubes |
publisher |
MDPI AG |
series |
Applied Sciences |
issn |
2076-3417 |
publishDate |
2018-11-01 |
description |
Carbon nanotubes are materials that have been investigated for diverse applications including the adsorption of metals. However, scarce literature has described their behavior in the case of the adsorption of precious metals. Thus, this work reports the efficient adsorption of gold from cyanide or chloride media on multiwalled carbon nanotubes (MWCNTs). In a cyanide medium, gold was adsorbed from alkaline pH values decreasing the adsorption as the pH values were increased to more acidic values. In a chloride medium, the MWCNTs were able to load the precious metal and an increased HCl concentration (0.1⁻10 M), in the aqueous solution, had no effect on the gold uptake onto the nanotubes. From both aqueous media, the metal adsorption was well represented by the pseudo-second order kinetic model. In the cyanide medium, the film-diffusion controlled process best fitted the rate law governing the adsorption of gold onto the nanotubes, whereas in the chloride medium, the adsorption of the metal onto the nanotubes is best represented, both at 20 °C and 60 °C, by the particle-diffusion controlled process. With respect to the elution step, in cyanide medium gold loaded onto the nanotubes can be eluted with acidic thiourea solutions, whereas in the chloride medium, and due to that the adsorption process involved the precipitation of zero valent gold onto the multiwalled carbon nanotubes, the elution has been considered as a leaching step with aqua regia. From the eluates, dissolved gold can be conveniently precipitated as zero valent gold nanoparticles. |
topic |
multiwalled carbon nanotubes gold(I) gold(III) adsorption elution gold nanoparticles |
url |
https://www.mdpi.com/2076-3417/8/11/2264 |
work_keys_str_mv |
AT franciscojosealguacil adsorptionofgoldiandgoldiiiusingmultiwalledcarbonnanotubes |
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1725301941220671488 |