Synthesis and Characterisation of Activated Carbon from Agricultural Waste Materials in Enugu State

The conversion of agricultural waste materials into activated carbon represents an economically viable and environmentally sustainable approach to waste management, while simultaneously producing adsorbents for water treatment and industrial applications. This study synthesises activated carbon from rice husk and groundnut shell waste materials obtained from processing centres in Enugu State, South East Nigeria. Precursor materials were carbonised at 500 degrees Celsius and chemically activated using zinc chloride and phosphoric acid. The resulting activated carbon samples were characterised by Fourier-transform infrared spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller surface area analysis, iodine number, and methylene blue adsorption number. Adsorption efficiency was tested against methylene blue dye solution as a model pollutant using batch equilibrium experiments, and adsorption isotherms were fitted to Langmuir and Freundlich models. Results indicate that phosphoric acid-activated groundnut shell carbon exhibited the highest BET surface area and superior dye removal efficiency, achieving approximately 91 percent removal within 60 minutes at optimal conditions. Kinetic data followed the pseudo-second-order model. The study demonstrates that locally available agricultural residues in the South East can serve as low-cost precursors for functional adsorbent materials, supporting circular economy practices and contributing to water treatment applications in resource-limited settings. Keywords: activated carbon, agricultural waste, Enugu State, adsorption, water treatment