Removal of arsenic from aqueous streams with cerium (IV) oxide compositions
First Claim
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1. A method for removing arsenic from an aqueous stream, comprising:
- contacting a cerium (IV) oxide composition with an arsenic-containing aqueous stream, wherein the following are true;
(i) the cerium (IV) oxide composition has a zeta potential at about pH 7 of no more than about 16 mV and of more than about 1 mV;
(ii) the cerium (IV) oxide composition has a crystallite size of more than about 1 nm and less than about 19 nm;
(iii) the cerium (IV) oxide composition has an acidic site concentration of more than about 0.0001 acidic sites/kg and less than about 0.020 acidic sites/kg;
(iv) the cerium (IV) oxide composition has an isoelectric point of more than about pH 8.8; and
(v) the cerium (IV) oxide composition has an arsenic (III) removal capacity, at an initial concentration of arsenic (III) in the arsenic-containing aqueous stream of no more than about 440 ppb, of more than about 17.1 mg As(III)/g CeO2,wherein the contacting of the cerium (IV) oxide composition with the arsenic-containing aqueous stream removes some of the arsenic from the arsenic-containing aqueous stream.
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Abstract
A cerium (IV) oxide composition having unexpectedly greater arsenic loading capacities than oxides of cerium (IV) of the prior art are disclosed. The arsenic loading capacities are greater at low level equilibrium levels of arsenic. The cerium (IV) oxide composition is more effective at removing arsenite and arsenate. Moreover, the cerium (IV) oxide composition has a greater capacity for the previously more difficult to remove arsenite.
684 Citations
9 Claims
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1. A method for removing arsenic from an aqueous stream, comprising:
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contacting a cerium (IV) oxide composition with an arsenic-containing aqueous stream, wherein the following are true; (i) the cerium (IV) oxide composition has a zeta potential at about pH 7 of no more than about 16 mV and of more than about 1 mV; (ii) the cerium (IV) oxide composition has a crystallite size of more than about 1 nm and less than about 19 nm; (iii) the cerium (IV) oxide composition has an acidic site concentration of more than about 0.0001 acidic sites/kg and less than about 0.020 acidic sites/kg; (iv) the cerium (IV) oxide composition has an isoelectric point of more than about pH 8.8; and (v) the cerium (IV) oxide composition has an arsenic (III) removal capacity, at an initial concentration of arsenic (III) in the arsenic-containing aqueous stream of no more than about 440 ppb, of more than about 17.1 mg As(III)/g CeO2, wherein the contacting of the cerium (IV) oxide composition with the arsenic-containing aqueous stream removes some of the arsenic from the arsenic-containing aqueous stream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for removing arsenic from an aqueous stream, comprising:
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contacting a cerium (IV) oxide composition with an arsenic-containing aqueous stream, wherein the following conditions are true; (i) the cerium (IV) oxide composition has a zeta potential at about pH 7 of no more than about 16 mV and of more than about 1 mV; (ii) the cerium (IV) oxide composition has an acidic site concentration of more than about 0.0001 acidic sites/kg and less than about 0.020 acidic sites/kg; (iii) the cerium (IV) oxide composition has an isoelectric point of more than about pH 8.8; (iv) the cerium (IV) oxide composition has at least one of; (a) a particle size D10 of more than about 0.5 μ
m and no more than about 4 μ
m;(b) a particle size D50 of more than about 2 μ
m and no more than about 20 μ
m; and(c) a particle size D90 of more than about 12 μ
m and no more than about 50 μ
m; and(v) the cerium (IV) oxide composition has an arsenic (III) removal capacity, at an initial concentration of arsenic (III) in the arsenic-containing aqueous stream of no more than about 440 ppb, of more than about 17.1 mg As(III)/g CeO2, wherein the contacting of the cerium (IV) oxide composition with the arsenic-containing aqueous stream removes some of the arsenic from the arsenic-containing aqueous stream.
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Specification