Comparison of Biotic and Abiotic Sorption of Cu(II) and Zn(II) by Geothite

Abstract

In the present work, the abilities of natural and synthetic samples of goethite to remove Cu(II)and Zn(II) from the aqueous solutions were studied. Addition of bacteria was investigated to enhance the sorption properties of goethite samples. Synthetic goethite (GS) was prepared in laboratory conditions by hydrolysis of Fe3+ from acid solution. The bacterial strain Bacillus cereus used for adsorption experiments was isolated from the heavy metal polluted waste water of an industry plant. The effect of initial pH, initial metal ion concentration and addition of bacteria on the adsorption of copper and zinc ions onto the iron oxide has been studied. The Langmuir linearized model was applied to interpret the experimental data. Synthetic goethite had a higher sorption capacity for both metals than natural goethite. Cu(II) showed a higher affinity to both samples compare to Zn(II). The addition of bacteria increased the sorption capacity of the natural sample and decreased the sorption capacity of the synthetic sample dependent on the solution pH. The maximum value of adsorption capacity was achieved for the synthetic goethite: 2.85mg Cu(II) /g and 1.72mg Zn(II) /g. The addition of bacteria increased the maximum sorption capacity of GS to 3.29 and 2.47mg/g for Cu(II) and Zn(II), respectively.