Preparation and Evaluation of Activated Carbon from Rice Husk for Methylene Blue Dye Removal in Borno State

The discharge of synthetic dyes from textile and dyeing industries is a major source of surface water pollution in many parts of North East Nigeria, and the development of low-cost, locally sourced adsorbents is an important environmental research priority. This study prepared activated carbon from rice husk, an abundantly available agricultural waste in Borno State, and evaluated its effectiveness for methylene blue dye removal from aqueous solution. Rice husk was carbonised at 600 degrees Celsius and chemically activated with potassium hydroxide at a 1:1.5 impregnation ratio. The product was characterised by BET surface area analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, and proximate analysis. Batch adsorption experiments were conducted to study the effects of initial dye concentration, contact time, pH, adsorbent dose, and temperature on removal efficiency. The prepared activated carbon had a BET surface area of 886 m2/g and an iodine number of 934 mg/g. Removal efficiency of 98.6 percent was achieved for methylene blue at 50 mg/L initial concentration with 1 g/L adsorbent dose at pH 8 and 60 minutes contact time. Adsorption equilibrium data fitted the Langmuir isotherm model better than the Freundlich model, with a maximum adsorption capacity of 142 mg/g. Pseudo-second-order kinetics described the adsorption process accurately. These results establish rice husk-derived activated carbon as a highly effective and economically attractive adsorbent for dye removal applicable in wastewater management contexts across North East Nigeria.

Keywords: activated carbon, rice husk, methylene blue, adsorption isotherm, Borno State