Removal of arsenic from aqueous streams with cerium (IV) oxide compositions
First Claim
Patent Images
1. A composition, comprising:
- a cerium (IV) oxide composition having sorbed arsenic, wherein the following conditions (i) through (vi) are true;
(i) the cerium (IV) oxide composition has, prior to the arsenic being sorbed, 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, prior to the arsenic being sorbed, 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, prior to the arsenic being sorbed, an arsenic (III) removal capacity of more than about 17.1 mg As(III)/g CeO2 when exposed to an arsenic-containing aqueous stream having an arsenic (III) concentration of no more than about 440 ppb,wherein the cerium (IV) oxide composition has, after the arsenic being sorbed, an acidic site concentration of less than about 0.0001 acidic sites/kg.
2 Assignments
0 Petitions
Accused Products
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.
681 Citations
16 Claims
-
1. A composition, comprising:
-
a cerium (IV) oxide composition having sorbed arsenic, wherein the following conditions (i) through (vi) are true; (i) the cerium (IV) oxide composition has, prior to the arsenic being sorbed, 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, prior to the arsenic being sorbed, 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, prior to the arsenic being sorbed, an arsenic (III) removal capacity of more than about 17.1 mg As(III)/g CeO2 when exposed to an arsenic-containing aqueous stream having an arsenic (III) concentration of no more than about 440 ppb, wherein the cerium (IV) oxide composition has, after the arsenic being sorbed, an acidic site concentration of less than about 0.0001 acidic sites/kg. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
Specification