Removal of chromium (vi) from aqueous solution by ulmus leaves
The presence of heavy metals in thinking water sources and in edible agricultural crops can be harmful to human. It is well known that heavy metals can be toxic, e.g. they damage nerves, liver and bones and they block functional groups of vital enzymes (Ewan and Pamphlet, 1996). In the recent years, increasing awareness of water pollution and its far reaching effects has prompted efforts towards pollution abatement. Among the different heavy metals from toxic pollutants introduced into natural waters, chromium is of high concern (Donmez and Aksu, 2002). The two major sources chromium contamination are electroplating, metal finishing industries (hexavalent chromium) and tanneries (trivalent chromium). Chromium occurs most frequently as Cr (III) or Cr (VI) in aqueous solutions (Dakikiy et at., 2002). Both valences of chromium are potentially harmful but hexavalent chromium poses a greater risk due to its carcinogenic properties (Dakikiy et at., 2002).