Characterization of acid functional groups of carbon dots by nonlinear regression data fitting of potentiometric titration curves

被引:55
作者
Alves, Larissa A. [1 ]
de Castro, Arthur H. [1 ]
de Mendonca, Fernanda G. [2 ]
de Mesquita, Joao P. [1 ]
机构
[1] Fed Univ Jequitinhonha & Mucuri Valleys, Dept Chem, Rodovia MGT 367 Km 583,5000 Alto da Jacuba, BR-39100000 Diamantina, MG, Brazil
[2] Univ Fed Minas Gerais, Dept Chem, Ave Antonio Carlos,6627 Pampulha, BR-31270901 Belo Horizonte, MG, Brazil
关键词
Nanostructures; Oxidized carbon dots; Acids functional groups; Potentiometric titration; Electrochemical techniques; Nonlinear regression; TEMPERATURE-PROGRAMMED DESORPTION; SURFACE-CHEMISTRY; ACTIVATED CARBONS; PHOSPHORIC-ACID; QUANTUM DOTS; AUTOMATIC TITRATIONS; BIODIESEL PRODUCTION; EQUIVALENCE VOLUMES; ELECTRON-TRANSFER; AQUEOUS SULFIDE;
D O I
10.1016/j.apsusc.2016.02.128
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The oxygenated functional groups present on the surface of carbon dots with an average size of 2.7 +/- 0.5 nm were characterized by a variety of techniques. In particular, we discussed the fit data of potentiometric titration curves using a nonlinear regression method based on the Levenberg-Marquardt algorithm. The results obtained by statistical treatment of the titration curve data showed that the best fit was obtained considering the presence of five Brensted-Lowry acids on the surface of the carbon dots with constant ionization characteristics of carboxylic acids, cyclic ester, phenolic and pyrone-like groups. The total number of oxygenated acid groups obtained was 5 mmol g(-1), with approximately 65% (similar to 2.9 mmol g(-1)) originating from groups with pKa < 6. The methodology showed good reproducibility and stability with standard deviations below 5%. The nature of the groups was independent of small variations in experimental conditions, i.e. the mass of carbon dots titrated and initial concentration of HCl solution. Finally, we believe that the methodology used here, together with other characterization techniques, is a simple, fast and powerful tool to characterize the complex acid-base properties of these so interesting and intriguing nanoparticles. (C) 2016 Elsevier B.V. All rights reserved.
引用
收藏
页码:486 / 495
页数:10
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