Thermodynamic and Kinetic Studies: Adsorption of Fe (III) onto Corncob

Heavy metals released into the surface and ground water has been a major preoccupation for many years because of their increased discharge, acute toxicity, non-biodegradable nature and tendency for bioaccumulation [1-3]. Iron a common contaminant enters the water bodies through effluents of industries such as electroplating, mining, steel processing etc. The presence of Fe (II) in water results in undesirable color, odour and taste which makes water unfit for industry and domestic consumption [4]. Different methods of treating wastewater containing heavy metal ions have been developed over years which include coagulation, ion exchange, membrane separation, reverse osmosis, solvent extraction, chemical precipitation, electroflotation etc. [5]. Although, the above-mentioned methods are efficient in treating high concentration of heavy metal ions, nevertheless these techniques also have disadvantages including incomplete metal removal, high consumption of reagent and very high cost incurred in the process. For the lower concentration of heavy metal ions, adsorption is a much preferable technique and activated carbon has been widely applied for treating industrial wastewater [6]. Low-cost agricultural waste byproducts, such as sugarcane bagasse [7], rice husks [8], sawdust [9], coconut husks [10], and oil palm shell [11], have been investigated to eliminate heavy metals from wastewater. Agricultural residues are usually composed of lignin and cellulose as the major constituents with other polar functional groups such as alcohols, aldehydes, ketones, carboxylic acids and ethers that facilitate metal complexation resulting biosorption of heavy metal ions [12] from wastewaters. The purpose of the present study was to investigate the removal of Fe (III) ions on corncob powder (CCP) from aqueous solution. The experiments were carried out in a batch system and iron adsorption was investigated with respect to contact time, initial metal ion concentration, pH, adsorbent dose and temperature. The adsorption isotherm, kinetics and thermodynamics of the sorption process were studied.