Rice Husk Silica Adsorbent for Removal of Hexavalent Chromium Pollution from Aquatic Solutions

The present study investigates the effectiveness of a new adsorbent prepared from agriculturalwastes, namely rice husk silica as well as raw rice husk and rice bran to remove Cr +6 from aquatic solutions.The raw rice husk was collected from North of Iran. But rice husk silica was prepared by burning of clean ricehusk inside a muffle furnace at a temperature of 800°C for 4 hours after acid leaching. The effects of fourparameters: contact time (30 to 90 min), pH values (2 to 9), adsorbents dosages (0.5 to 1.5 g/L) and initialconcentration (1.0 to 15 mg/L) were investigated to remove Cr+6. The silica derived from rice husk showed ahigh percentage of SiO2 up to 94.24%. But