Claims for Patent: 6,174,442

Summary for Patent: 6,174,442

Title:	Adsorbent for phosphate from an aqueous medium, production and use of said adsorbent
Abstract:	An adsorbent for phosphate from aqueous medium, particularly for inorganic phosphate or phosphate bound to foodstuffs from body fluids or foodstuffs, which contains beta-iron hydroxide stabilized by carbohydrates and/or by humic acid.
Inventor(s):	Geisser; Peter (St. Gallen, CH), Philipp; Erik (St. Gallen, CH)
Assignee:	Vifor (International) AG (St. Gallen, SE)
Application Number:	09/077,944
Patent Claims:	1. An adsorbent for adsorbing phosphate from aqueous medium, comprising polynuclear beta-iron hydroxide stabilized by at least one member selected from the group consisting of carbohydrates and humic acid. 2. A process for producing the adsorbent according to claim 1, comprising: mixing an aqueous solution of a base with an aqueous solution of an iron (III) salt containing chloride ions with formation of a suspension with a pH of 3 to 10, allowing the suspension to stand, washing a precipitate obtained with water, suspending the still moist precipitate in water with formation of a suspension with an iron content of up to 6% by weight, and adding at least one member selected from the group consisting of one or more carbohydrates and humic acid in an amount such that a solid obtained contains a maximum of 40% by weight of iron. 3. A process according to claim 2, comprising: mixing an aqueous alkali metal carbonate or alkali metal bicarbonate solution with an aqueous solution of an iron (III) salt containing chloride ions with formation of a suspension with a pH higher than 6, allowing the suspension to stand, washing precipitate obtained with water to remove the chloride ions present, suspending the still moist precipitate in water with formation of a suspension with an iron content of up to 6% by weight, and adding at least one member selected from the group consisting of one or more carbohydrates and humic acid in an amount such that the solid obtained contains a maximum of 40% by weight of iron. 4. A process according to claim 2, comprising: using iron (III) chloride as the iron (III) salt. 5. A process according to claim 2, comprising: using sodium carbonate or sodium bicarbonate as the base. 6. An adsorbent according to claim 1, wherein the stabilized polynuclear beta-iron hydroxide is obtained by a process comprising: mixing an aqueous solution of a base with an aqueous solution of an iron (III) salt containing chloride ions with formation of a suspension with a pH of 3 to 10, allowing the suspension to stand, washing a precipitate obtained with water, suspending the still moist precipitate in water with formation of a suspension with an iron content of up to 6% by weight, and adding at least one member selected from the group consisting of one or more carbohydrates and humic acid in an amount such that a solid obtained contains a maximum of 40% by weight iron. 7. A process according to claim 2, wherein the carbohydrate comprises saccharose or dextrin or a mixture thereof. 8. An adsorbent according to claim 1, further comprising a calcium salt. 9. A process for using the adsorbent according to claim 1, comprising adsorbing phosphate from an aqueous medium. 10. A process for using the adsorbent according to claim 1, comprising adsorbing inorganic phosphate and phosphate bonded to foodstuffs from body fluids. 11. A process for using the adsorbent according to claim 1, comprising adsorbing inorganic phosphate and phosphate bonded to foodstuffs from gastrointestinal tract contents. 12. A process for using stabilized polynuclear beta-iron hydroxide defined in claim 1, comprising producing adsorbents for inorganic phosphate and phosphate bonded to foodstuffs from body fluids and from gastrointestinal tract contents, simultaneously with intake of food. 13. A process for using the adsorbent according to claim 1, comprising adsorbing inorganic phosphate and phosphate bonded to foodstuffs, from said foodstuffs. 14. A process for using stabilized polynuclear beta-iron hydroxide as defined in claim 1, comprising producing adsorbents for admixture with foodstuffs.