An evaluation of microwave-assisted fusion and microwave-assisted acid digestion methods for determining elemental impurities in carbon nanostructures using inductively coupled plasma optical emission spectrometry

Shashikant P Patole; Filipa Simões; Tahir F Yapici; Bashir H Warsama; Dalaver H Anjum; Pedro M F J Costa

doi:10.1016/j.talanta.2015.10.053

An evaluation of microwave-assisted fusion and microwave-assisted acid digestion methods for determining elemental impurities in carbon nanostructures using inductively coupled plasma optical emission spectrometry

Talanta. 2016 Feb 1:148:94-100. doi: 10.1016/j.talanta.2015.10.053. Epub 2015 Oct 21.

Authors

Shashikant P Patole¹, Filipa Simões², Tahir F Yapici³, Bashir H Warsama³, Dalaver H Anjum⁴, Pedro M F J Costa²

Affiliations

¹ Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia. Electronic address: Shashikant.Patole@kaust.edu.sa.
² Physical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
³ Analytical Core Laboratory, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.
⁴ Advanced Imaging and Characterization Laboratory, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia.

PMID: 26653428
DOI: 10.1016/j.talanta.2015.10.053

Abstract

It is common for as-prepared carbon nanotube (CNT) and graphene samples to contain remnants of the transition metals used to catalyze their growth; contamination may also leave other trace elemental impurities in the samples. Although a full quantification of impurities in as-prepared samples of carbon nanostructures is difficult, particularly when trace elements are intercalated or encapsulated within a protective layer of graphitic carbon, reliable information is essential for reasons such as quantifying the adulteration of physico-chemical properties of the materials and for evaluating environmental issues. Here, we introduce a microwave-based fusion method to degrade single- and double-walled CNTs and graphene nanoplatelets into a fusion flux thereby thoroughly leaching all metallic impurities. Subsequent dissolution of the fusion product in diluted hydrochloric and nitric acid allowed us to identify their trace elemental impurities using inductively coupled plasma optical emission spectrometry. Comparisons of the results from the proposed microwave-assisted fusion method against those of a more classical microwave-assisted acid digestion approach suggest complementarity between the two that ultimately could lead to a more reliable and less costly determination of trace elemental impurities in carbon nanostructured materials.

Keywords: Carbon nanotubes; Graphene nanoplatelets; Inductively coupled plasma optical emission spectrometry; Metrology; Microwave-assisted acid digestion; Microwave-assisted fusion.