Controllable preparation of nano-MgO and investigation of its bactericidal properties

Samples of nano-MgO with varying particle sizes were prepared by four different methods using Mg(NO3)(2) (.) 6H(2)O, Na2CO3, urea and ammonia as raw materials and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), low temperature N-2 adsorption-desorption measurements and FT-IR spectroscopy. Bactericidal experiments with Bacillus subtilis var. niger and Staphylococeus aureus were carried out using as-synthesized nano-MgO samples and the bactericidal mechanism was also investigated. The results showed that the bactericidal efficacy of nano-MgO increases with decreasing particle size. The bactericidal efficacy of the samples was compared with that of TiO2, a common photoactive bactericidal material. The nano-MgO has better bactericidal activity, both when used directly and as an additive in an interior wall paint. Furthermore, nano-MgO is active even in the absence of irradiation. (c) 2005 Elsevier Inc. All rights reserved.