Abstract

A novel carbonaceous adsorbent with heavy metal removal from aqueous solution was prepared from rice husk using sulfur impregnation. The rice husk was immersed in 0.05 - 3 M K₂S solution to prepare sulfur-immersed materials, and the immersed-materials were heated at 100 - 700 oC in nitrogen gas to produce the sulfur-impregnated carbonaceous adsorbent by pyrolysis. The contents of carbon and sulfur in the adsorbent and abilities of adsorbent to remove heavy metals from aqueous solution were examined. The product prepared from rice husk immersed in 1 M K2S solution by pyrolysis at 300 oC indicates a maximum removal for nickel ion. This product has the removal ability of the heavy metals, Ni²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Cu²⁺ and Fe³⁺. With increasing the pH of the solution, removal of heavy metal increase, and the order of increase for heavy metal removal is Fe³⁺ > Pb²⁺ ≒ Cu²⁺ > Zn²⁺> Cd²⁺ > Nⁱ²⁺. The order of selectivity of the adsorbent in the mixed solution indicates Fe³⁺ > Pb²⁺ > Cu²⁺ > Cd²⁺ > Zn²⁺≒ Ni²⁺, and the product can remove all metal ions in the mixed solution above pH 6.