Synthesis and Characterisation of Activated Carbon from Rice Husk for Water Treatment Applications in Ebonyi State

Rice husk constitutes a major agro-industrial waste stream in Ebonyi State, South East Nigeria, where large-scale paddy processing generates millions of tonnes annually. This study synthesises activated carbon from Ebonyi rice husk via pyrolysis at 500 degrees Celsius followed by chemical activation with potassium hydroxide solution. Activated carbon samples were characterised using proximate analysis, BET surface area measurement, scanning electron microscopy, and Fourier-transform infrared spectroscopy. Adsorption performance was evaluated using methyl orange dye and chromium (VI) ions at varying concentrations, contact times, and pH conditions. The prepared activated carbon exhibited a BET surface area of 1,024 m2/g, significantly higher than unactivated rice husk char. Methyl orange removal efficiency reached 94.2% within 60 minutes under optimal conditions, while chromium removal efficiency attained 87.6% at pH 3. Equilibrium adsorption data conformed to the Freundlich isotherm model, and kinetic studies indicated pseudo-second-order behaviour. Comparative performance tests against commercial activated carbon revealed that the rice husk-derived product achieved 85 to 92% of the commercial benchmark at a fraction of the production cost. The findings validate rice husk from Ebonyi State as a sustainable precursor for low-cost water treatment adsorbents, with implications for improving access to safe water in rural South East Nigerian communities. Keywords: rice husk, activated carbon, adsorption, water treatment, Ebonyi State