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Surface engineered magnetic nanoparticles for removal of toxic metal ions and bacterial pathogens

Singh, Sarika, Barick, K.C., Bahadur, D.
Journal of hazardous materials 2011 v.192 no.3 pp. 1539-1547
Escherichia coli, Fourier transform infrared spectroscopy, X-ray diffraction, arsenic, bacteria, cadmium, chromium, cobalt, copper, electrostatic interactions, ion exchange, iron oxides, lead, metal ions, nanoparticles, nickel, pathogens, succinic acid, temperature, thiols, toxicity, transmission electron microscopy, zeta potential
Surface engineered magnetic nanoparticles (Fe₃O₄) were synthesized by facile soft-chemical approaches. XRD and TEM analyses reveal the formation of single-phase Fe₃O₄ inverse spinel nanostructures. The functionalization of Fe₃O₄ nanoparticles with carboxyl (succinic acid), amine (ethylenediamine) and thiol (2,3-dimercaptosuccinic acid) were evident from FTIR spectra, elemental analysis and zeta-potential measurements. From TEM micrographs, it has been observed that nanoparticles of average sizes about 10 and 6nm are formed in carboxyl and thiol functionalized Fe₃O₄, respectively. However, each amine functionalized Fe₃O₄ is of size ∼40nm comprising numerous nanoparticles of average diameter 6nm. These nanoparticles show superparamagnetic behavior at room temperature with strong field dependent magnetic responsivity. We have explored the efficiency of these nanoparticles for removal of toxic metal ions (Cr³⁺, Co²⁺, Ni²⁺, Cu²⁺, Cd²⁺, Pb²⁺ and As³⁺) and bacterial pathogens (Escherichia coli) from water. Depending upon the surface functionality (COOH, NH₂ or SH), magnetic nanoadsorbents capture metal ions either by forming chelate complexes or ion exchange process or electrostatic interaction. It has been observed that the capture efficiency of bacteria is strongly dependent on the concentration of nanoadsorbents and their inoculation time. Furthermore, these nanoadsorbents can be used as highly efficient separable and reusable materials for removal of toxic metal ions.