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US 4,790,958 AGranted
Chemical method of ferric ion removal from acid solutions
AssigneeThe Dow Chemical Company
InventorArthur S. Teot
Life of this patent
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Abstract
Onium species of nitrogen, phosphorus or sulfur are useful to precipitate ferric ion, existing as tetrahaloferrate anion, from strong haloacid solutions. The precipitants are useful in the field of well acidizing, because tetrahaloferrate anion attacks polymeric and viscoelastic surfactant thickeners used to thicken haloacid solutions.
Claims32
A process for thickening a strong aqueous haloacid in the presence of tetrahaloferrate ions comprising in any order the steps of:
- (a) contacting said acid solution with a thickening amount of polymeric thickener or viscoelastic surfactant thickener composition containing cationic viscoelastic surfactants;
- and
- (b) contacting said acid solution with an onium species conforming to the structural formula:
- (MRn).sup.+ X.sup.- (I)
- wherein
- M is nitrogen, phosphorus or sulfur,
- at least two R groups are hydrocarbyl or inertyl-substituted hydrocarbyl groups comprising from about 3 to about 12 carbon atoms and each other R group is hydrogen, a hydrocarbyl group or inertly-substituted hydrocarbyl group, said R groups being chosen such that the moiety (MR.sub.n).sup.+ is soluble in the acid solution but is not surface active and forms an insoluble precipitate with tetrahaloferrate anions,
- n is the number of R groups bonded to the onium forming species, and
- X.sup.- is a suitable counterion, under conditions and in an amount such that said onium species forms an insoluble precipitate with substantial amounts of the tetrahaloferrate anions and such that substantial viscosity of the acid composition is maintained.
6 more elements
A thickened composition comprising:
- (a) an aqueous haloacid solution;
- (b) a thickening amount of a polymeric thickener or a viscoelastic surfactant composition selected from the group consisting of nonionic and cationic viscoelectric surfactants;
- and
- (c) a precipitant for tetrahaloferrate anions comprising an onium species conforming to the structural formula:
- (MR.sub.n).sup.+ X.sup.- (I)
- wherein
- M is nitrogen, phosphorus or sulfur,
- at least two R groups are hydrocarbyl or inertly-substituted hydrocarbyl groups comprising from about 3 to about 12 carbon atoms and each other R group is hydrogen, a hydrocarbyl group or inertly-substituted hydrocarbyl group, said R groups being chosen such that the moiety (MR.sub.n).sup.+ is soluble in the acid solution but is not surface active and forms an insoluble precipitate with tetrahaloferrate anions,
- n is the number of R groups bonded to the onium forming species, and
- X.sup.- is a suitable counterion;
- said precipitant being present in a concentration sufficient to precipitate substantial amounts of tetrahaloferrate anion such that substantial viscosity of the acid composition is maintained.
8 more elements
Dependencies are inferred from the claim text.