Nitric acid vapor phase oxidation of carbon nanotubes using Mg(NO3)(2)-HNO3-H2O ternary mixture is proposed as a further development and significant improvement of the method employing the sole azeotropic HNO3 solution. Based on the so-called "salt effect," the addition of Mg(NO3)(2) to HNO3-H2O solution allows varying the acid vapor concentration within a wide range, even beyond the azeotropic one (>68wt%). Ternary mixture containing 20wt% Mg(NO3) 2 and variable amount of liquid HNO3 (30-58wt%) is used for the functionalization process, achieving nitric acid vapor concentrations in the range 25-93wt%. The increase of acid concentration in vapor phase produces a significant augment of the functionalization degree and a linear increase of the concentration of carboxylic acids groups, which can thus be simply tuned.
Highly Versatile and Efficient Process for CNT Oxidation in Vapor Phase by Means of Mg(NO3)(2)-HNO3-H2O Ternary Mixture
MILONE, Candida;PIPEROPOULOS, Elpida;
2014-01-01
Abstract
Nitric acid vapor phase oxidation of carbon nanotubes using Mg(NO3)(2)-HNO3-H2O ternary mixture is proposed as a further development and significant improvement of the method employing the sole azeotropic HNO3 solution. Based on the so-called "salt effect," the addition of Mg(NO3)(2) to HNO3-H2O solution allows varying the acid vapor concentration within a wide range, even beyond the azeotropic one (>68wt%). Ternary mixture containing 20wt% Mg(NO3) 2 and variable amount of liquid HNO3 (30-58wt%) is used for the functionalization process, achieving nitric acid vapor concentrations in the range 25-93wt%. The increase of acid concentration in vapor phase produces a significant augment of the functionalization degree and a linear increase of the concentration of carboxylic acids groups, which can thus be simply tuned.Pubblicazioni consigliate
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