USE OF FLUORESCENCE TO MONITOR HYDROPHOBIC CONTAMINANTS IN A PAPERMAKING PROCESS

1 . A method of monitoring one or more types of hydrophobic contaminants in a papermaking process comprising:

a. obtaining a bulk sample of fluid from said papermaking process;

b. selecting a hydrophobic dye that is capable of interacting with said contaminants in said fluid and fluorescing in said fluid;

c. adding said dye to said fluid and allowing a sufficient amount of time for said dye to interact with said contaminants in said fluid;

d. measuring the fluorescence of the dye in said fluid;

e. correlating the fluorescence of the dye with the concentration of said contaminants; and

f. optionally controlling the amount of one or more chemicals that reduce or inactivate said contaminants which are added to said papermaking process.

2 . The method of claim 1 further comprising: measuring the turbidity of said fluid.

3 . The method of claim 2 wherein said turbidity of said fluid is measured before and after the addition said chemicals.

4 . The method of claim 1 , wherein said fluid is filtered or diluted or a combination thereof prior to said addition of said dye or said fluorescent measurement of said dye.

5 . The method of claim 1 , wherein said dye does not include N-(n-butyl)-4-(n-butylamino)-naphthalimide.

6 . The method of claim 1 wherein said fluid is obtained from a wet end of said papermaking process.

7 . The method of claim 1 wherein said dye is mixed with a solvent prior to its addition to said fluid.

8 . The method of claim 1 , wherein said contaminants are selected from the group consisting of: pitch, fiber, filler, fines, coated broke, mill broke, recycle, groundwood, thermal mechanical pulp, deinked pulp furnish, chemi-thermal mechanical pulp, chemical pulp, ink, adhesives, stickies, tackies, waxes, binders and dissolved and/or colloidal substances, and a combination thereof.

9 . The method of claim 1 , wherein said method is an on-line method and/or batch sample method.

10 . The method of claim 1 , wherein said fluorometric measurement is performed at a pre-set basis, intermittent basis, and/or continuous basis.

11 . The method of claim 1 , wherein said fluorometric measurement is performed with a handheld fluorometer.

12 . The method of claim 1 , wherein said fluid is an aqueous filtrate of a pulp slurry.

13 . A method for measuring the effectiveness of one or more chemicals that decrease the amount of one or more hydrophobic contaminants in a papermaking process:

a. monitoring one or more types of contaminants in a papermaking process comprising: obtaining a bulk sample of fluid from said papermaking process; selecting a hydrophobic dye that is capable of interacting with said contaminants in said fluid and fluorescing in said fluid; adding said dye to said fluid and allowing a sufficient amount of time for said dye to interact with said contaminants in said fluid; measuring the fluorescence of the dye in said fluid; and correlating the fluorescence of the dye with the concentration of said contaminants;

b. adding one or more chemicals to said papermaking process that decrease the amount of said hydrophobic contaminants; and

c. re-measuring the amount of contaminants in said papermaking process by performing step (a) at least one more time; and

d. optionally controlling the amount of said chemicals that are added to said papermaking process.

14 . The method of claim 13 , wherein said chemicals are at least one of the following: a fixative; a detackifier; a dispersant; a surfactant; and a retention aid.

15 . A method of monitoring one or more types of hydrophobic contaminants in a papermaking process consisting essentially of:

a. obtaining a bulk sample of fluid from said papermaking process;

b. selecting a hydrophobic dye that is capable of interacting with said contaminants in said fluid and fluorescing in said fluid;

c. adding said dye to said fluid and allowing a sufficient amount of time for said dye to interact with said contaminants in said fluid;

d. measuring the fluorescence of the dye in said fluid;

e. correlating the fluorescence of the dye with the concentration of said contaminants; and

f. optionally controlling the amount of one or more chemicals that reduce or inactivate said contaminants which are added to said papermaking process.