Characterization of Chemically Activated Pyrolytic Carbon Black Derived from Waste Tires as a Candidate for Nanomaterial Precursor.

Reyna Berenice González-González,Alberto Mendoza,Lucy T González,Mario Moisés Alvarez,Everardo González-González,Marc Madou,Sigfrido Iglesias-González,Sergio O Martinez-Chapa

doi:10.3390/nano10112213

Reyna Berenice González-González, Alberto Mendoza + Show 6 more

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https://doi.org/10.3390/nano10112213

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Abstract

Pyrolysis is a feasible solution for environmental problems related to the inadequate disposal of waste tires, as it leads to the recovery of pyrolytic products such as carbon black, liquid fuels and gases. The characteristics of pyrolytic carbon black can be enhanced through chemical activation in order to produce the required properties for its application. In the search to make the waste tire pyrolysis process profitable, new applications of the pyrolytic solid products have been explored, such as for the fabrication of energy-storage devices and precursor in the synthesis of nanomaterials. In this study, waste tires powder was chemically activated using acid (H2SO4) and/or alkali (KOH) to recover pyrolytic carbon black with different characteristics. H2SO4 removed surface impurities more thoroughly, improving the carbon black’s surface area, while KOH increased its oxygen content, which improved the carbon black’s stability in water suspension. Pyrolytic carbon black was fully characterized by elemental analysis, inductively coupled plasma–optical emission spectrometry (ICP-OES), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), N2 adsorption/desorption, scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDS), dynamic light scattering (DLS), and ζ potential measurement. In addition, the pyrolytic carbon black was used to explore its feasibility as a precursor for the synthesis of carbon dots; synthesized carbon dots were analyzed preliminarily by SEM and with a fluorescence microplate reader, revealing differences in their morphology and fluorescence intensity. The results presented in this study demonstrate the effect of the activating agent on pyrolytic carbon black from waste tires and provide evidence of the feasibility of using waste tires for the synthesis of nanomaterials such as carbon dots.

Highlights

The environmental problems related to the inadequate disposal of 1.2 billion waste tires annually worldwide, in addition to another four billion already accumulated in landfills and stockpiles, have led to an urgent need for their proper utilization and valorization [1]
The waste tire powder used as feedstock was analyzed through proximal and elemental analysis to identify which changes generated in the waste tire powder were due solely to the activation process
The decrease in ash content has been previously studied by some authors [15,56], who reported that H2SO4 demonstrated good performance as a demineralization agent

Summary

Introduction

The environmental problems related to the inadequate disposal of 1.2 billion waste tires annually worldwide, in addition to another four billion already accumulated in landfills and stockpiles, have led to an urgent need for their proper utilization and valorization [1]. Additives, such as sulfur and other chemicals, are added to render a crosslinked structure that enhances some physical properties of the final product, such as durability, wear resistance, abrasion and weathering resistance, and mechanical properties [4,5,6].

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