Process for improved recovery of onium hydroxide from compositions containing process residues
A process for recovering an onium hydroxide from a composition containing onium ions and a process residue, including providing a composition containing onium ions and a process residue; adding a quantity of a surfactant to the composition to obtain a surfactant-modified composition; providing a cation exchange media; collecting the onium ions by applying the surfactant-modified composition to the cation exchange media wherein the onium ions become bound to and retained by the cation exchange media and the process residue and the surfactant do not become bound to the cation exchange media and are substantially not retained by the cation exchange media; and recovering the onium ions from the cation exchange media as an onium hydroxide by applying a cation-containing hydroxide composition to the cation exchange media.
1. A process for recovering an onium hydroxide from a composition containing onium ions and a process residue, comprising:
providing a composition containing onium ions and a process residue;
adding a quantity of a surfactant to the composition to obtain a surfactant-modified composition;
providing a cation exchange media;
collecting the onium ions by applying the surfactant-modified composition to the cation exchange media wherein the onium ions become bound to and retained by the cation exchange media and the process residue and the surfactant do not become bound to the cation exchange media and are substantially not retained by the cation exchange media; and
recovering the onium ions from the cation exchange media as an onium hydroxide by applying a cation-containing hydroxide composition to the cation exchange media.
2. The process of claim 1 further comprising loading the cation exchange media into at least one vessel.
3. The process of claim 1 further comprising loading the cation exchange media into at least two vessels connected in series, wherein a first effluent from a first vessel of the at least two vessels may be applied as feed to a second vessel of the at least two vessels.
4. The process of claim 3 wherein in the collecting, the surfactant-modified composition is applied to the cation exchange media in the first vessel, the first effluent is applied as the feed to the second vessel, and the recovering is carried out on at least the first vessel when a predetermined pH change is detected in a second effluent from the second vessel.
5. The process of claim 3 wherein in the collecting, the surfactant-modified composition is applied to the cation exchange media in the first vessel, the first effluent is applied as feed to the cation exchange media in the second vessel, and a second effluent from the second vessel is applied as feed to the cation exchange media in a third vessel of the at least two vessels and a third effluent is obtained.
6. The process of claim 5 , wherein the collecting is continued until a predetermined pH change is detected in the third effluent.
7. The process of claim 6 wherein the recovering is carried out on at least the first vessel following detection of the predetermined pH change.
8. The process of claim 6 wherein following the detection of the predetermined pH change, the third effluent is fed to a fourth vessel.
9. The process of claim 1 wherein the process residue comprises a photoresist residue.
10. The process of claim 1 wherein the onium is a quaternary ammonium.
11. The process of claim 10 wherein the quaternary ammonium has a general formula (I):
wherein in formula (I), R 1 , R 2 , R 3 and R 4 are each independently an alkyl group containing from 1 to about 8 carbon atoms.
12. The process of claim 1 wherein the surfactant is a hydroxyl-containing nonionic surfactant.
13. The process of claim 1 wherein the surfactant is a hydroxyalkylcellulose, wherein the alkyl is methyl, ethyl, propyl or butyl.
14. The process of claim 13 wherein the surfactant is a hydroxyethylcellulose.
15. The process of claim 14 wherein the hydroxyethylcellulose has a molecular weight in the range from about 10,000 to about 1,000,000, or from about 100,000 to about 500,000, or about 250,000.
16. The process of claim 12 wherein the hydroxyl-containing nonionic surfactant is a poly(ethyleneglycol) or poly(ethyleneoxide) having a molecular weight in the range from about 20,000 to about 2,000,000, or about 200,000.
17. The process of claim 12 wherein the surfactant is a poly(vinylalcohol) (PVA) having a molecular weight in the range from about 20,000 to about 2,000,000, or about 66,000 to about 80,000.
18. The process of claim 12 wherein the surfactant is a guar gum.
19. The process of claim 1 wherein the quantity of the selected surfactant in the surfactant-modified composition is in the range from about 10 ppm to about 10,000 ppm based on the total quantity of the surfactant-modified composition.
20. The process of claim 1 wherein the cation-containing hydroxide is sodium hydroxide, potassium hydroxide, lithium hydroxide, or a combination of any two or more thereof.
21. The process of claim 1 further comprising regenerating the cation exchange media by applying an acid to the cation exchange media.