Methods of making low color lignin

1. A method of producing light colored lignin, the method comprising:

reacting a lignin composition with a hypochlorite composition having about 5% to about 70% available chlorine; and

reacting the hypochlorite-treated lignin with hydrogen peroxide at a concentration of about 5 wt % to about 50 wt % to produce the light colored lignin,

wherein the lignin composition includes at least one of sulfonated lignin, lignosulfonate, or both.

2. The method of claim 1 , wherein at least one of:

(i) prior to the step of reacting the lignin composition with a hypochlorite composition, adjusting at least one of the pH to less than 7, adjusting the temperature to less than about 100° C., or both;

(ii) the step of reacting the lignin composition with a hypochlorite composition includes at least one of adjusting the pH to less than 7, adjusting the temperature to less than about 100° C., or both;

(iii) the step of reacting the hypochlorite treated lignin with hydrogen peroxide includes at least one adjusting the pH to greater than 7, adjusting the temperature to less than about 100° C., or both; or

(iv) a combination thereof.

3. The method of claim 2 , further comprising a step of filtering the hypochlorite treated lignin to remove salts formed during the reaction.

4. The method of claim 3 , further comprising a step of filtering the light colored lignin to remove salts formed during the reaction.

5. The method of claim 4 , further comprising sparging the hypochlorite treated lignin.

6. The method of claim 5 , wherein at least one of:

sparging is performed for at least about 1 hour (e.g., about 1 hour to about 5 hours);

sparging is a nitrogen or air sparging; or

a combination thereof.

7. The method of claim 1 , wherein the hypochlorite composition includes at least one of a sodium salt, a potassium salt, a calcium salt, a magnesium salt, or a combination thereof.

8. The method of claim 1 , wherein the amount of the hypochlorite composition reacting with the lignin composition is about 10% to about 250% of the lignin composition weight.

9. The method of claim 1 , wherein the amount of the hydrogen peroxide reacting with the hypochlorite treated lignin is about 10% to about 250% of the lignin composition weight.

10. The method of claim 2 , wherein (i), (ii) or both are performed with at least one of hydrochloric acid, phosphoric acid, sulfuric acid, acetic acid, or a combination thereof.

11. The method of claim 2 , wherein (iii) is performed with at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, or a combination thereof.

12. The method of claim 1 , wherein the lignin composition includes at least one of blocked sulfonated lignin, blocked lignosulfonate or a combination thereof.

13. The method of claim 1 , wherein the lignin composition includes at least one of unblocked sulfonated lignin, unblocked lignosulfonate or a combination thereof.

14. The method of claim 1 , wherein the lignin composition is an aqueous solution having about 1% to about 60% w/v sulfonated lignin or lignosulfonate.

15. The method of claim 1 , further comprising at least one of:

concentrating the low color lignin;

drying the low color lignin; or

both.

16. The method of claim 15 , wherein the low color lignin is spray dried.

17. The method of claim 1 , wherein the color of a blocked lignin composition comprising blocked lignosulfonates, blocked sulfonates lignins or a combination thereof, is reduced by about 80% to about 99% relative to the untreated blocked lignin composition.

18. The method of claim 1 , wherein the color of a unblocked lignin composition comprising unblocked lignosulfonates, unblocked sulfonated lignins or a combination thereof, is reduced by about 70% to about 99% relative to the untreated unblocked lignin composition.

19. The method of claim 1 , wherein the light colored lignin is color stable at temperatures up to about 150° C., a pH ranging from about 8 to about 10 or both.