Use of ozone to control bioburden in precipitated calcium carbonate slurry (PCC)
The present disclosure is directed to a method for reducing bacteria in a precipitated calcium carbonate (CaCO 3 ) slurry, the method including: adding water to calcium oxide (CaO) to form Ca(OH) 2 ; treating the Ca(OH) 2 with CO 2 gas to form a slurry including precipitated CaCO 3 ; neutralizing the slurry; and exposing the slurry that was neutralized to ozone in an amount sufficient to reduce bacteria in the precipitated calcium carbonate slurry. Oral care compositions including the precipitated calcium carbonate of the disclosed process are also described.
1. A method for reducing bacteria in a precipitated calcium carbonate (CaCO 3 ) slurry, the method comprising:
adding water to calcium oxide (CaO) to form Ca(OH) 2 ;
treating the Ca(OH) 2 with CO 2 gas to form a slurry comprising precipitated CaCO 3 ;
neutralizing the slurry; and
exposing the slurry that was neutralized to ozone in an amount sufficient to reduce bacteria in the precipitated calcium carbonate slurry,
wherein a solid concentration of precipitated CaCO 3 in the slurry ranges from about 12% w/w to about 40% w/w;
wherein the concentration of ozone in the neutralized slurry ranges from about 5 ppm to about 25 ppm.
2. The method of claim 1 , wherein the exposing comprises injecting ozone gas into the slurry that was neutralized.
3. The method of claim 1 , wherein the method further comprises:
mixing the slurry that was neutralized and the ozone to create a mixture; and
recirculating the mixture into a tank.
4. The method of claim 3 , wherein the method further comprises sampling the slurry after the mixing and before the recirculating to determine a degree of reduction of the bacteria.
5. The method of claim 3 , wherein the mixing comprises mixing the slurry and the ozone using a static mixer.
6. The method of claim 1 , wherein a log reduction of the bacteria ranges from about a 1 log reduction to about a 5 log reduction.
7. The method of claim 1 , wherein a log reduction of the bacteria ranges from about a 4 log reduction to about a 5 log reduction.
8. The method of claim 1 , wherein a concentration of ozone in the slurry that was neutralized is about 25 ppm.
9. The method of claim 1 , wherein the bacteria comprise gram positive bacteria.
10. The method of claim 1 , wherein the method further comprises:
sampling the slurry that was neutralized before exposing the slurry to ozone;
assessing a bioburden before exposing the slurry to ozone;
sampling the slurry that was neutralized after exposing the slurry to ozone; and
assessing a bioburden after exposing the slurry to ozone.
11. The method of claim 10 , wherein the sampling the slurry that was neutralized after exposing the slurry to ozone occurs about 10 seconds to about 40 minutes after the slurry was exposed to ozone.
12. The method of claim 10 , wherein the sampling the slurry that was neutralized after exposing the slurry to ozone occurs about 3 seconds to about 10 seconds after the slurry was exposed to ozone.
13. The method of claim 10 , wherein a pH of the slurry that was neutralized ranges from about 6.9 to about 8.5.
14. The method of claim 1 , wherein a temperature of the slurry that was neutralized ranges from about 25° C. to about 47° C.
15. The method of claim 14 , wherein a temperature of the slurry that was neutralized ranges from about 28° C. to about 32° C.
16. The method of claim 1 , wherein the method further comprises drying the slurry to isolate the precipitated CaCO 3 and form dried CaCO 3 .
17. The method of claim 16 , wherein the method further comprises combining the dried CaCO 3 with an oral care ingredient to form an oral care composition.