Development of a chemical-free floatation technology for the purification of vein graphite and characterization of the products

Gamaralalage R A Kumara,Buddika Karunarathne,Hsin-Hui Huang,Masamichi Yoshimura,Rajapakse Mudiyanselage G Rajapakse,K Kanishka H De Silva,Mantilaka Mudiyanselage M G P G Mantilaka Mantilaka,Herath Mudiyanselage G T A Pitawala

doi:10.1038/s41598-021-02101-9

Abstract

A novel and simple flotation technique has been developed to prepare high-purity graphite from impure graphite. In this method, a suspension of pristine powdered graphite (PG) is dispersed and stirred in water without adding froth formers or supportive chemicals. This makes fine particles of graphite move upwards and float on water. X-ray diffraction (XRD) analysis reveals that the floated graphite (FG) has a lower c-axis parameter, indicating the removal of interlayer impurities. A notable increase in the intensity ratio of the D band to G band in the Raman spectra indicates that the FG has more edge defects due to their smaller crystallite sizes. Transmission electron microscopic (TEM) analysis shows the number of layers in FG has been reduced to 16 from 68 in PG. The absence of C=O vibration of Fourier Transformed Infrared (FT-IR) spectroscopy in treated and untreated samples suggests that their layers are not significantly oxidized. However, X-ray photoelectron spectroscopic (XPS) analysis shows the presence of C–O–C ether functionalities, possibly on edge planes. Further, the product has higher purity with increased carbon content. Therefore, the technique is helpful for the value enhancement of graphite, the reduction of the chemical cost of the conventional techniques, environmental friendliness, and improvement of its applications.

Highlights

A novel and simple flotation technique has been developed to prepare high-purity graphite from impure graphite
Graphite is one of the important naturally occurring minerals characterized by its inherent specific properties such as low hardness, metallic lustre, high lubricity, refractoriness, high heat and electrical conductivities, and ability to withstand to high temperatures
Out of 5.0 g of powdered graphite (PG) taken for floating in water 4.5 g of floated graphite (FG) was recovered

Summary

Introduction

A novel and simple flotation technique has been developed to prepare high-purity graphite from impure graphite. Graphite has specific gravity around 1.9–2.3, the hydrophobic nature of fine graphite particles aids the floatation process when water is used as the floating medium. We reveal an effective chemical-free, simple floatation technique developed to obtain highpurity and well-crystalline graphite products by floating fine particles of graphite on water.

Results

Conclusion