CVD Synthesis of Solid, Hollow, and Nitrogen-Doped Hollow Carbon Spheres from Polypropylene Waste Materials

Pranav K Tripathi,Neil J Coville,Shane Durbach

doi:10.3390/app9122451

Pranav K Tripathi, Neil J Coville + Show 1 more

Open Access

https://doi.org/10.3390/app9122451

Copy DOI

Journal: Applied Sciences	Publication Date: Jun 15, 2019
Citations: 10	License type: CC BY 4.0

Affiliation: University of the Witwatersrand

Abstract

Plastic waste leaves a serious environmental footprint on the planet and it is imperative to reduce this. Consequently, recycling has been regarded as an important approach in providing one solution to this problem. In this study, we enhanced the value of polypropylene (PP) plastic waste by using it as a hydrocarbon source to synthesize a variety of spherical carbon nanomaterials. Here, a CVD method was used to decompose the PP initially into a hydrocarbon gas (propylene). Thereafter, PP was employed to synthesize solid carbon spheres (SCSs), hollow carbon spheres (HCSs), and nitrogen-doped hollow carbon spheres (NHCSs). The latter two were made using a silica template while the N-doping was achieved by the addition of melamine to PP. Yields obtained were between 12–20%. The SCSs (d = 800 nm to 1200 nm), HCSs (id = 985 nm; shell width = 35 nm), and NHCSs (id = ca. 1000 nm; shell width = 40 nm) were all characterized by TEM, SEM, TGA, laser Raman spectroscopy, and XPS.

Highlights

The disposal of plastic waste material ranging from the nano- to the macro-scale has become a serious contemporary environmental issue [1,2,3]
The conversion of the solid plastic waste investigated in this study, that is, used polypropylene centrifuge tubes, required a two-stage CVD furnace for the synthesis of carbon materials
TEMspheres, data revealed that the carbonscarbon to make similar

Summary

Introduction

The disposal of plastic waste material ranging from the nano- to the macro-scale has become a serious contemporary environmental issue [1,2,3]. Approaches to the disposal of plastic waste vary and include: 1) Generating polymers that will decompose with time via built-in chemical procedures [5,6], 2) The development of enzymes/bacteria that will decompose polymers [7], 3) Landfill options, and 4) Thermal decomposition by combustion [8]. In this latter option, the possibility exists to convert these waste plastics into high-value materials that could be re-used by society [9,10]. We report on the use of used PP centrifuge tubes as a carbon source to make SCSs, HCSs, and nitrogen-doped HCSs (NHCSs)

Chemicals

Synthesis of SCSs

Synthesis of HCSs

Nitrogen-Doped HCSs

Results and Discussion

High magnification

Conclusions