%0 Journal Article
%T Adsorption of Hexavalent Chromium from Aqueous Solution Using Chemically Activated Carbon Prepared from Locally Available Waste of Bamboo (Oxytenanthera abyssinica)
%A Tamirat Dula
%A Khalid Siraj
%A Shimeles Addisu Kitte
%J ISRN Environmental Chemistry
%D 2014
%R 10.1155/2014/438245
%X This study reports on the adsorption of Hexavalent Chromium from aqueous solutions using activated carbon prepared from bamboo (Oxytenanthera abyssinica) waste by KOH activation heating in an electrical furnace at 1073£¿K for 3£¿hrs. Batch adsorption experiments were also carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage, and temperature of the solution. Kinetic studies of the data showed that the adsorption follows the pseudo-second-order kinetic model. Thermodynamic parameters showed that adsorption on the surface of BWAC was feasible, spontaneous in nature, and exothermic between temperatures of 298 and 318£¿K. The equilibrium data better fitted the Freundlich isotherm model for studying the adsorption behavior of Hexavalent Chromium by BWAC. IR spectrum for loaded and unloaded BWAC was obtained using FT-IR spectrophotometer. Adsorption efficiency and capacity of Hexavalent Chromium were found to be 98.28% at pH 2 and 59.23£¿mg/g at 300£¿K. 1. Introduction Out of the various toxic pollutants chromium and its compounds are considered as the most dangerous inorganic water pollutants. Chromium compounds present in the effluents as a result of electroplating, metal finishing, magnetic tapes, wood preservation, leather tanning, pigments, and chemical manufacturing industries [1, 2]. They can also present in rocks, soils, plants, and animals. This heavy metal occurs in the environment in two oxidation states: trivalent Cr(III) and hexavalent Cr(VI). Cr(III) is considered as an essential trace nutrient for human, while Cr(VI), in turn, is highly toxic [3, 4]. Because of its mutagenic and carcinogenic properties, it includes skin irritation to lung cancer, as well as kidney, liver, and gastric damage [5]. Owing to the different toxicities of Cr(VI), there is a great interest in the speciation and determination of chromium species in environment. A number of treatment methods for the removal of chromium ions from aqueous solutions have been reported, mainly reduction, ion exchange, electrodialysis, electrochemical precipitation, evaporation, solvent extraction, reverse osmosis, chemical precipitation, and adsorption. Most of these methods suffer from drawbacks such as high operational costs and incomplete removal or the disposal of the residual metal sludge [6]. Adsorption by activated carbon is one of the effective techniques for Cr(VI) ion removal from wastewater because of the high surface area, highly porous character, and relatively low cost of the adsorbent [7, 8]. Activated carbon is especially known for
%U http://www.hindawi.com/journals/isrn.environmental.chemistry/2014/438245/