Removing Methylene Blue from Aqueous Solutions Using Rice Husk Silica Adsorbent

The main goal of this study is to investigate the efficiency of the silica derived from the raw rice husk in the removal of methylene blue from aqueous solutions. The effects of initial concentrations of methylene blue, pH, the adsorbent dose, and the contact time on methylene blue removal efficiency were carried out in batch reactors. The silica derived from the raw rice husk was prepared in a furnace at 800 degrees C for 4 hours after acid leaching with sulfuric acid and chloridric acid. The rice husk silica showed more porosity than the raw rice husk with a median pore radius of 2.4 nm and a high specific surface area up to 226.3 m(2)g(-1). The maximum removal efficiency of methylene blue by the rice husk silica under the initial concentration of 10 mgL(-1) methylene blue, 1 gL(-1) adsorbent mass, 60 min contact time, and pH 8 was 96.7%. Correlation coefficients of the adsorption models have shown a better matching of methylene blue adsorption by the rice husk silica with the Langmuir isotherm model. The results of this study show that the rice husk silica can be applied to remove environmental pollutants such as methylene blue due to the low cost and availability of rice husks.