Silica adsorbent on magnetic substrate
AssigneeW. R. Grace & Co.-Conn.
InventorsJames Neil Pryor, Linda Lee Crump
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Abstract
Adsorbent particles comprising superparamagnetic and/or low Curie Temperature transition metal-containing cores surrounded by a hydrous siliceous oxide coating can be formed by an aqueous process wherein the core is precipitated from an aqueous solution and a siliceous oxide coating is deposited thereon while complete drying of the core is avoided until after the siliceous oxide is deposited. The resulting siliceous adsorbents exhibit strong superparamagnetic and/or low Curie temperature magnetic properties with low transition metal leachability.
Claims20
A particulate adsorbent comprising particles which consist essentially of:
- (a) at least one core consisting essentially of a transition metal-containing component selected from the group consisting of superparamagnetic materials, low Curie Temperature materials, and mixtures thereof, and
- (b) a siliceous oxide coating on the surface of said core(s),
- wherein said coating covers the entire surface of said core(s) such that said adsorbent particles have a transition metal leach value when present as 0.33 g dried adsorbent particles in 20 ml of 1N hydrochloric acid aqueous solution for 15 minutes of less than about 50 ppm metal based on the weight of said solution.
Dependencies are inferred from the claim text.