Adsorption properties of carbon nanotubes depending on the temperature of their synthesis and subsequent treatment

A correlation between the temperature of the synthesis of carbon nanotubes (CNT) by method of catalytic pyrolysis from ethanol on a nickel catalyst and their ability for the modification of oxidation under various conditions and also their adsorption capacity to a number of metal ions is demonstrated. The study of infrared spectra in correlation with the total acidity of the CNT synthesized and modified under various conditions has shown that the samples synthesized at 400°C possess the maximum ability for modification. This can be explained by the higher deficiency of their structures at low synthesis temperatures. Adsorption isotherms of silver, copper, lead, cadmium, zinc, iron, and magnesium ions under batch and dynamic modes were studied, depending on pH and element concentration in the solution. It was found that CNT synthesized at 400°C and treated with conc. HNO3 in an autoclave at 110–120°C possess the maximum adsorption capacity of all the studied elements, which exceeds the capacity of active coal, traditionally used for these purposes, by several times. The attained adsorption capacity is 5–10 times higher than that reported in the literature for carbon nanotubes in relation to the same elements. Prospects of using CNT as collectors for the preconcentration of trace impurities in spectroscopic methods of analysis are considered.