Dye removal by using activated carbon from rice husk: optimization by using Response Surface Methodology (RSM)

Abstract

Adsorption processes are being widely used in many industrial wastewater treatment for dyes removal. Despite of its wide application, commercial activated carbon is not feasible and need a high media replacement cost. Rice husk as a low-cost adsorbent was studied as an alternative for dyes removal. Adsorption of methyl orange (MO) onto rice husk pretreated with potassium hydroxide (RHC) and commercial activated carbon (AC) were investigated. The preparation of optimized RHC was determined by using Response Surface Methodology (RSM). The optimization preparation conditions of RHC suggested by RSM was impregnation ratio 1:4, activation temperature at 500 ºC and activation time of 4 hours. The removal efficiency (%) and adsorption capacity (mg/g) of MO influence by contact time, adsorbent dosages, initial concentration of solution and pH of solution were analyzed. The contact time for RHC to reach equilibrium was at 210 minutes. While the adsorbent dosages of RHC and initial concentration of MO solution to achieve maximum adsorption efficiency of MO was 0.6 g and 20 mg/L respectively. In addition, initial concentration at the pH of 10 is the optimum for MO removal by RHC.