Methods of pulp fiber treatment
In some embodiments, a method may include treating pulp in pulp and paper mills. The methods may include providing a peracetate oxidant solution and generating a reactive oxygen species. The peracetate solution may include peracetate anions and a peracid. In some embodiments, the peracetate solution may include a pH from about pH 10 to about pH 12. In some embodiments, the peracetate solution has a molar ratio of peracetate anions to peracid ranging from about 60:1 to about 6000:1. In some embodiments, the peracetate solution has a molar ratio of peracetate to hydrogen peroxide of greater than about 16:1. The peracetate oxidant solution may provide enhanced treatment methods of bleaching, brightening, and delignifying pulp fibers involving the use of peracetate oxidant solutions.
1. A method of treating pulp, the method comprising:
delignifying the pulp in a delignification stage;
after the delignification stage, contacting the pulp with a parent oxidant solution, the contacting comprising adding the parent oxidant solution to the pulp; and after the adding, mixing a mixture with the pulp with the added parent oxidant solution; and
the parent oxidant solution being a peracetate oxidant solution to generate a reactive oxygen species in the mixture, wherein the peracetate oxidant solution as added to the pulp comprises:
a pH in a range of from about 10 to about 12;
peracetate anions and a peracid with a molar ratio of peracetate anions to peracid of from 60:1 to 6000:1; and
a peracetate anion to hydrogen peroxide molar ratio greater than about 16:1; and
wherein as added to the pulp the peracetate oxidant solution is at a higher pH than the pulp and during the mixing the mixture with the pulp and the peracetate oxidant solution comprises a pH in a range of from about pH 6 to about pH 11 and with the pH of the mixture decreasing over time as the mixing continues.
2. The method of claim 1 , wherein during the contacting the pulp has a temperature from between about 50° C. to about 95° C.
3. The method of claim 2 , wherein the temperature accelerates the generation of reactive oxygen species from the parent oxidant solution in the mixture.
4. The method of claim 1 , further comprising extracting lignin from the pulp through action of the peracetate oxidant solution.
5. The method of claim 1 , further comprising, after the contacting, bleaching the pulp with a bleaching sequence in which the pulp is bleached with chlorine dioxide.
6. The method of claim 1 , wherein the pulp comprises a pulp consistency from 0.1 to 20% pulp fiber during the contacting.
7. The method of claim 1 , wherein the reactive oxygen species generated is a singlet oxygen.
8. The method of claim 1 , further comprising sequentially dosing the pulp with the peracetate oxidant solution.
9. The method of claim 1 , wherein the delignification stage comprises oxygen delignification of the pulp.
10. The method of claim 1 , wherein the delignification stage comprises sulfide digestion.
11. The method of claim 1 , wherein the delignification stage does not include contacting the pulp with a peracetate solution.
12. The method of claim 1 , wherein the method is in the absence of chlorine dioxide treatment prior to and during the contacting.
13. A method of treating pulp, the method comprising:
delignifying the pulp in a delignification stage;
after the delignification stage, contacting the pulp with a parent oxidant solution, the contacting comprising adding the parent oxidant solution to the pulp; and after the adding, mixing a mixture with the pulp with the added parent oxidant solution; and
the parent oxidant solution being a peracetate oxidant solution to generate a reactive oxygen species in the mixture, wherein the peracetate oxidant solution as added to the pulp comprises:
a pH in a range of from about 10 to about 12;
peracetate anions and a peracid with a molar ratio of peracetate anions to peracid of from 60:1 to 6000:1; and
a peracetate anion to hydrogen peroxide molar ratio greater than about 16:1; and
wherein the contacting the pulp comprises contacting the pulp during a washing stage.
14. The method of claim 13 , wherein as added to the pulp the peracetate oxidant solution is at a higher pH than the pulp and during the mixing the mixture with the pulp and the peracetate oxidant solution comprises a pH in a range of from about pH 6 to about pH 11 and with the pH of the mixture decreasing over time as the mixing continues.
15. A method of treating pulp, the method comprising:
delignifying the pulp in a delignification stage;
after the delignification stage, contacting the pulp with a parent oxidant solution, the contacting comprising adding the parent oxidant solution to the pulp; and after the adding, mixing a mixture with the pulp with the added parent oxidant solution; and
the parent oxidant solution being a peracetate oxidant solution to generate a reactive oxygen species in the mixture, wherein the peracetate oxidant solution as added to the pulp comprises:
a pH in a range of from about 10 to about 12;
peracetate anions and a peracid with a molar ratio of peracetate anions to peracid of from 60:1 to 6000:1; and
a peracetate anion to hydrogen peroxide molar ratio greater than about 16:1; and
wherein the delignification stage comprises alkaline peroxide extraction.
16. A method of treating pulp, the method comprising:
delignifying the pulp in a delignification stage;
after the delignification stage, contacting the pulp with a parent oxidant solution, the contacting comprising adding the parent oxidant solution to the pulp; and after the adding, mixing a mixture with the pulp with the added parent oxidant solution; and
the parent oxidant solution being a peracetate oxidant solution to generate a reactive oxygen species in the mixture, wherein the peracetate oxidant solution as added to the pulp comprises:
a pH in a range of from about 10 to about 12;
peracetate anions and a peracid with a molar ratio of peracetate anions to peracid of from 60:1 to 6000:1; and
a peracetate anion to hydrogen peroxide molar ratio greater than about 16:1; and
wherein the delignification stage comprises enzymatic digestion.