Spectroscopic analysis of Sri Lankan vein graphite, industrially purified using green and chemical approaches

Sri Lanka is well known for high-quality vein graphite, which can be exported with value addition at a higher price than the raw form to remain competitive in the global market. The present study aims at industrial scale production of Sri Lankan vein graphite above 99.9% purity level using ecofriendly and chemical methods. For the first time a novel mechanical floatation method was followed to purify vein graphite above 99% on mass scale. Acid leaching method was followed subsequently to remove most of the impurities from graphite at industrial scale as well. Subsequently, alkali-acid method was followed for further purification of graphite. The raw and treated graphite were subjected to X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis to verify any structural change resulting from the treatment process. XRD analysis showed that the crystalline structure of graphite has not significantly changed upon treatment. XPS and FTIR spectroscopic analysis also revealed that there is no apparent functional groups attached to graphite structure after treatment. SEM images demonstrated a flaky appearance of graphite without any clear changes in morphology even after the treatment with acids at commercial level quantitates. The results illustrated that combination of the flotation technique and chemical treatment allow graphite purification well above 99.9% carbon without significant structural changes.