Investigating the removal of hexavalent chromium from aqueous solutions by functionalized carbon derived from rice husk

Hexavalent chromium is a heavy metal with harmful effects on surface and ground water. Its removal from contaminated water and waste water has received great interest in recent years. This study aimed to evaluate the absorption of hexavalent chromium from aquatic environments using functionalized carbon produced from rice husk as an inexpensive and biological adsorbent.
This experimental study investigated the effects of pH (2-10), adsorbent dose (5-20 g/l), initial chromium concentration (5-20 mg/l), contact time (5-60 min), temperature (1-40 °C), and mixing rate (100-500 rpm) on removal of hexavalent chromium from aqueous solutions using functionalized carbon made from rice husk. The results of absorption in equilibrium conditions were analyzed by Langmuir isotherm model. UV/V Spectrophotometer T80 was employed to assess the obtained samples of hexavalent chromium at a wavelength of 540. The diagrams were drawn using the Excel software.
The most efficient removal of hexavalent chromium occurred at pH=2 and optimal dose of 10 g/l. As the initial hexavalent chromium concentration increased from 5 to 20 mg/lit, the removal percentage from reduced from 97.3 to 85.7%. Additionally, along with increased contact time and mixing speed, the removal efficiency improved.
Functionalized carbon derived from rice husk with a maximum efficiency of 97% is very effective in the removal of hexavalent chromium from aqueous solutions.