Removal of Dyes by using Rice Husk as Agricultural Solid Waste Adsorbent: Experimental investigation

In batch adsorption tests, Rice Husk (RH) Nano Activated Carbon (NAC) was employed to remove methylene blue (MB) and black B (BB) colours from synthetic solutions. For the two dyes of varying concentrations (50-300 mg/l), the influence of several operational parameters were tested, including pH (1-11), contact time (15-75 minutes), and temperatures (30-600C). The high adsorption capacity was achieved at 30°C and pH 3 for MB and pH 11 for BB. After 60 minutes, the adsorption equilibrium was reached. Adsorption isotherms were determined, and the results were examined using the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models. The Langmuir and Freundlich isotherm models were both advantageous for MB dye, whereas Langmuir was only favourable for BB dye. The researchers looked at two kinetic models: pseudo first order and pseudo second order kinetics. For both colours, the uptake rate of the NAC adsorbate obeyed a pseudo second order kinetic model, according to the findings.