Waste-Derived Carbon Nanostructures

An exponential and unorthodox growth in global population has led to unorthodox and exponential growth in universal development, and thus, the demands related to universal development are increasing, leading to an exponential increase in the production of waste materials. Recent scientific articles estimate annual global waste production at between 7 to 8 billion tons. This waste, with its harmful environmental and health effects, poses a significant challenge to the scientific community. A number of measures need to be taken for pollution control and population control, as well as allocation of substantial funding for projects on converting waste into value-added products. In this regard, several scientific communities have reported some unique research in this area, such as efficient waste management and cost-effective carbon nanomaterial production [1]. A multitude of applications have made carbon materials more and more popular in recent years including sensing, catalysis, energy storage, gene therapy, drug delivery, bioimaging, and metal adsorption. There are various types of carbon materials used for all these purposes, including nanodiamonds, carbon nanotubes, graphene, fullerenes, reduced graphene oxide, graphitic carbon nitride, graphene oxide, activated carbon, and carbon nanofibers [2]. Many methods are reported for synthesizing carbon material such as microwave-assisted pyrolysis, hydrothermal carbonation, molten salt process, the Bball milling method, and single-step pyrolysis under inert atmosphere [3]. Mukesh et al. synthesized graphene by using rice husk in microwave-assisted pyrolysis [4]. Chen et al. (2018) derived carbonaceous nanomaterials using the hydrothermal carbonization method [5]. Xie et al. (2020) used molten salt process for the synthesis of nitrogen-doped biochar nanosheets and checked their catalytic activity for organic pollutants [6]. Tran et al. (2018) convertedchitin biomass into organo-dispersible strong nanofibers using the ball milling method [7]. Various types of waste are used in the production of carbon materials like biomass waste, such as rice husk, fruits peels, sugarcane waste, shell waste, seeds waste etc. Another type is plastic waste in which includes various type of waste such as polyvinyl chloride (PVC), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS) etc., and also there are waste vehicle tires which are used in the synthesis of carbon nanostructure. Throughout the last ten years, researchers have developed excellent ideas for fabricating waste-to-value products [8].