Chemical Modification of Imperata cylindrica Leaf Powder for Heavy Metal Ion Adsorption

Abstract

Imperata cylindrica leaf was used as raw material to prepare two different adsorbents through chemical modification by using sulfuric acid and phosphoric acid. These two adsorbents, sulfuric acid-modified I. cylindrica leaf-based adsorbent (SIC) and phosphoric acid-modified I. cylindrica leaf-based adsorbent (PIC), were used to adsorb nickel ions (Ni2+) from aqueous solutions. The I. cylindrica leaf-based adsorbent and modified I. cylindrica leaf-based adsorbents were characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). Different operational parameters such as initial solution pH, adsorbent size, adsorbent dosage, initial Ni2+ ion concentration, and temperature were studied. The adsorption isotherm and the adsorption kinetics were studied systematically. Based on the FT-IR spectrum before and after adsorption of Ni2+ ions, the adsorption mechanism involved both ion exchange and complexation between Ni2+ ions and functional groups on the surface of adsorbents. There was no sulfur and phosphorus detected in the aqueous solutions after adsorption. Therefore, SIC and PIC are effective in adsorbing Ni2+ ions and will not cause secondary pollution to the environment.