Enhancing Carbonaceous Char Derived from Cashew Shell Pyrolysis as a Renewable Coal Alternative

Abstract

Purpose: This paper aims to evaluate the potential of carbonaceous char from cashew nut shell pyrolysis as a sustainable alternative to coal. By converting agricultural waste into a valuable energy resource, this research aims to address two critical challenges: effective waste management and the development of sustainable energy alternatives.

Methodology: The research methodology focused on converting cashew nutshell waste into a renewable energy source through a systematic process. Raw cashew nut shells were cleaned, dried at 60°C for 24 hours, and ground to a uniform size of 2-3 mm for consistent pyrolysis. The shells underwent pyrolysis in an oxygen-free environment to produce carbonaceous char, which was then chemically activated using phosphoric acid. After reacting at room temperature for two hours, the mixture was heated at 650°C in a muffle furnace to enhance the char’s surface area and porosity. Post-activation, the char was washed with water and methanol, sonicated to remove impurities, and dried before being analysed using FTIR for structural changes. The ash content of the treated char was measured to evaluate its suitability as a coal substitute, ensuring precision throughout.

Results & Findings: The results of the study showed that the carbonaceous char derived from cashew nut shells exhibited significant improvements after undergoing chemical activation. The activation process using phosphoric acid (H₃PO₄) effectively increased the surface area and porosity of the char, which enhanced its adsorption properties. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of functional groups such as C=C, C=O, and C≡C, indicating successful structural modifications of the char post-activation. The ash content was reduced to 7%, a favourable result, as lower ash levels improve the char’s industrial applicability. The char demonstrated improved combustion properties, making it a promising renewable substitute for coal.

Originality/Value: The originality of this paper lies in its innovative use of cashew nut shells, a widely overlooked agricultural waste, to produce carbonaceous char as a renewable coal substitute. By optimizing the chemical activation process with phosphoric acid (H₃PO₄), the study enhances the char's surface area and adsorption capacity, significantly improving its potential for industrial applications.

Type of Paper: Exploratory research