Chemically Activated Carbon Synthesized from Rice Husk for Adsorption of Methylene Blue in Polluted Water

Abstract

Rice husk (RH)-based activated carbons (ACs) were successfully manufactured and used as an adsorbent for the removal of methylene blue (MB) dye from polluted water. ACs were created by impregnating RH char with sodium hydroxide and then activating it for 1 h in a nitrogen environment at various activation temperatures. The characteristics of the obtained ACs were confirmed using Brunauer-Emmett-Teller analysis, scanning electron microscopy, X-ray diffraction analysis, and Fourier-transform infrared spectroscopy. The prepared ACs' pore volume and surface area increased with increasing temperature. The maximum specific surface area of the ACs sample was 729.4 m2/g at 900°C activation temperature. Adsorption was used to remove MB dye from polluted water using the obtained product. The effect of experimental parameters like adsorbent dosage, initial MB dye concentration, contact time, temperature, and pH of the MB dye solution was studied. The synthesized ACs were found to remove 80% of the MB dye under optimal conditions of pH (8), initial concentration (50 mg/L), and contact time (120 min). To represent the fitness of the adsorption data, the Langmuir and Freundlich isotherm models were used. The Langmuir model was found to be the best fit to equilibrium data, with R2 = 0.9972. Similarly, using pseudo first-order and pseudo second-order kinetic models, MB dye adsorption on ACs followed the pseudo-second order with an R2 value of 0.99719. The results show that synthesized RH-based ACs have a high potential for use as an effective adsorbent for removing dye from polluted water.