Column material for the capture of heavy metal and precious metal ions
Composite ion-exchange materials for use in an ion-exchange column are provided. Also provided are ion-exchange columns packed with the materials and methods for using the materials to remove metal ions from samples, such as waste water samples. The composite ion-exchange materials comprise a composite material comprising a metal chalcogenide and an alginate, wherein the composite material is mixed with a granular material.
1. An ion-exchange column comprising:
a column; and
an ion-exchange material packing the column, the ion-exchange material comprising a mixture of:
particles of a composite material, each of the particles of the composite material comprising a metal chalcogenide and an alginate, wherein the metal chalcogenide is characterized in that the metal chalcogenide undergoes ion exchange with metal ions in a sample, when the sample is passed through the column; and
a granular phase comprising grains of an inert material,
wherein grains of the inert material are not part of the particles of the composite material.
2. The ion-exchange column of claim 1 , wherein the metal chalcogenide has the nominal formula A 2x M x Sn 3-x S 6 , where x has a value in the range from about 0.5 to about 1; A is Li + , Na + , K + , Rb + or Cs + ; and M is Mg 2+ , Ca 2+ , Mn 2+ , Mn 3+ , Zn 2+ , Fe 2+ or Fe 3+ .
3. The ion-exchange column of claim 2 , wherein the metal chalcogenide has the nominal formula K 2x M x Sn 3-x S 6 .
4. The ion-exchange column of claim 2 , wherein the weight ratio of particles of the composite material to the grains of inert material is in the range from about 1:3 to 3:1.
5. The ion-exchange column of claim 4 , wherein the grains of inert material comprise activated carbon, sand or silica powder.
6. The ion-exchange column of claim 1 , wherein the weight ratio of the particles of the composite material to the grains of the inert material is in the range from about 1:3 to 3:1.
7. The ion-exchange material of claim 1 , wherein the grains of inert material are activated carbon, sand or silica powder.
8. The ion-exchange material of claim 1 , wherein the grains of inert material have a mesh size in the range from about 15 to about 75.
9. A method of removing metal ions from a sample comprising the metal ions, the method comprising passing the sample through the ion-exchange column of claim 1 , whereby ion-exchange occurs between the metal chalcogenide and the metal ions in the sample; and collecting the sample exiting the column.
10. The method of claim 9 , wherein the metal chalcogenide has the nominal formula A 2x M x Sn 3-x S 6 , where x has a value in the range from about 0.5 to about 1; A is Li + , Na + , K + , Rb + or Cs + ; and M is Mg 2+ , Ca 2+ , Mn 2+ , Mn 3+ , Zn 2+ , Fe 2+ or Fe 3+ .
11. The method of claim 9 , wherein the sample is waste water from a nuclear reactor, an industrial plant or a mining operation.
12. The method of claim 10 , wherein the percentage of the metal ions removed is at least 99.9 wt. %.
13. The ion-exchange material of claim 1 , wherein the particles of the composite material include particles having diameters greater than 1 mm, but less than 7 mm.