Patent ID: 8685178

Claim:
A method for preparing metal-modified particles, the method comprising: providing a treatment chamber comprising: an elongate housing having longitudinally opposite ends and an interior space, the housing being closed at at least one longitudinal end and having at least a first inlet port for receiving a first formulation comprising a basic buffer system, a second inlet port for receiving a second formulation comprising a salt of a transition metal and silica particles into the interior space of the housing, and at least one outlet port through which a metal-modified particulate-containing formulation is exhausted from the housing following ultrasonic mixing of the first and second formulations to form the metal-modified particulate-containing formulation, the outlet port being spaced longitudinally from the first and second inlet ports such that the first and second formulations flow longitudinally within the interior space of the housing from the inlet ports to the outlet port; and an elongate ultrasonic waveguide assembly extending longitudinally within the interior space of the housing and being operable at a predetermined ultrasonic frequency to ultrasonically energize and mix the first and second formulations flowing within the housing, the waveguide assembly comprising an elongate ultrasonic horn disposed at least in part intermediate the first and second inlet ports and the outlet port of the housing and having an outer surface located for contact with the first and second formulations flowing within the housing from the first and second inlet ports to the outlet port, and a plurality of discrete agitating members in contact with and extending transversely outward from the outer surface of the horn intermediate the first and second inlet ports and the outlet port in longitudinally spaced relationship with each other, the agitating members and the horn being constructed and arranged for dynamic motion of the agitating members relative to the horn upon ultrasonic vibration of the horn at the predetermined frequency and to operate in an ultrasonic cavitation mode of the agitating members corresponding to the predetermined frequency and the first and second formulations being mixed in the chamber; delivering the first formulation via the first inlet port into the interior space of the housing; delivering the second formulation via the second inlet port into the interior space of the housing; ultrasonically mixing the first and second formulations via the elongate ultrasonic waveguide assembly operating in the predetermined ultrasonic frequency to imbed the metal ions into the subsurface of the silica particles such that no trace of the imbedded metal ions can be analytically detected on the surface of the silica particles.