Method for the synthesis of a zero-valent metal micro- and nanoparticles in the presence of a noble metal

Abstract

The invention regards a method for the synthesis of Zero-Valent metal micro- and nanoparticles, in which a first aqueous solution (SOL) of a salt of a noble metal (A) is mixed with a third neutral or basic aqueous solution (SOL) of an inorganic sulphur-based reducing agent (C), and wherein the mixture thus obtained is added to a second aqueous solution (SOL) of a salt of a transition metal (B) and a second aliquot of the inorganic reducing agent; such method provides that the amount of the inorganic reducing agent (C) is in a stoichiometric excess in the reduction reaction to Zero-Valent of both the salt of the noble metal (A) contained in the first solution (SOL) and the salt of the transition metal (B) contained in the second solution (SOL). The invention also regards Zero-Valent micro and nanoparticles, preferably bimetallic, obtained with the above method. More generally, the invention regards a method for reduction of a transition metal (B) to Zero-Valent metal by an inorganic reducing agent (C), by prior or concurrent reduction of a noble metal (A), wherein the amount of inorganic reducing agent (C) is in stoichiometric excess in the reduction reaction to Zero-Valent of both the noble metal (A) and the transition metal (B). The present invention finds preferred and advantageous application in the remediation and/or the treatment of contaminated water containing at least one polluting substance. The preferred embodiment of the present invention provides that the noble metal (A) is silver, that the transition metal (B) is iron and/or manganese, and the inorganic reducing agent (C) is chosen from borohydrides, dithionites and bisulphites.