Abstract
The magnetotactic bacteria have the properties of both capturing heavy metal ions and being quickly separated out from the wastewater, which makes them high quality adsorbents. The adsorption of ions usually shows selectivity in the multi component aqueous solutions. This paper investigated the mechanism of adsorption selectivity using the molecular dynamics method on the basis of periodic law of elements. A universal equation with respect to the mass, volume and charge of ions was deduced. Based on the analysis of the surficial properties, a model was built to describe the structure of magnetotactic bacteria using the organic groups. Then, the interface system of bacterium surface, aqueous solutions and heavy metal ions was developed and dynamics simulation was performed. It was found that the ion having smaller charge-mass ratio according to the periodic system of elements might be easier to be adsorbed. The ionic thermal motion could depress the adsorption of ions and might be one of the reasons which cause adsorption selectivity. Furthermore, the larger charge-mass ions were more inclined to be drifting away from the bacteria in the simulation. Key words: Magnetotactic bacteria, heavy metal, adsorption, charge-mass ratio, periodic law of elements, molecular simulation.
Highlights
The wastewater containing heavy metals has always been a troublesome problem in the fields of chemical, petrochemical and metallurgical industry
This paper investigated the mechanism of adsorption selectivity using the molecular dynamics method on the basis of periodic law of elements
A model cell of magnetotactic bacterium used in the wastewater treatment process was developed
Summary
The wastewater containing heavy metals has always been a troublesome problem in the fields of chemical, petrochemical and metallurgical industry. As a novel wastewater treatment technology in recent years, the biosorption-magnetic separation process has been used to extract the metals from aqueous solutions. Magnetotactic bacteria were used in this process to adsorb metals and external magnetic field was subsequently used to quickly draw the metal loaded microorganism out of the wastewater. Cu (II) and Ni (II) would be depressed in adsorption when they co-exist with Au (III) (Song et al, 2007). The magnetotactic bacteria are inclined to adsorb only one metal ion in the water system containing several cations. The industrial application of biosorption magnetic separation needs the knowledge of which metal would be extracted and which one would be depressed in the water treatment process
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