Unravelling the properties of microzonal carbon from waste hard rubber by selective thermal transformation via conventional heating and microwave irradiation

Abstract

Concerns regarding resource limitations and environmental pollution have led humankind towards a circular economy, where the primary objective is to convert waste into resources. In solidarity with the principles of the circular economy, for the first time, we have reported the synthesis of microzonal carbon by microrecycling of waste hard rubber using a conventional furnace (500 °C - 1500 °C; for 20min) and a microwave furnace (500 °C - 950 °C; for 5min). Microzonal carbon has been unveiled here as a hybrid carbon structure composed of ordered and disordered carbons. This study reveals the aspects of micorzonal carbon and analogises the effectiveness and performance of two different heating methods by way of various material characterisations. The overall analysis summarises that due to selective and rapid heating mechanism, the rate of change of structural properties of microzonal carbon, such as d-spacing (d002), crystallite size (Lc), and ID/IG band ratio, as well as the surface morphology, takes place rapidly in microwave heating than conventional heating. And it has been found that with the rise of temperature, the features of microzonal carbon become more prominent, such as the number of ordered carbon zone and mesopore volume increased, while micropore volume, surface area and interlayer spacing decreased. These evolving adjustments of features with temperature eventually ended up producing near-spherical shaped agglomerated microzonal carbon, with approximately 35–45 nm size. Waste hard rubber can have negative impacts on the environment unless they are disposed of properly. Synthesis of microzonal carbon via microrecycling of waste hard rubber can protect the environment from harsh consequences of waste hard rubber and ensure material sustainability to some extent or another. Therefore, microrecycling of waste hard rubber can fabricate a new horizon in the field of renewable carbon material synthesis, in the form of microzonal carbon.