Method for measuring a concentration of a compound in a liquid stream
AssigneeEvoqua Water Technologies LLC
InventorBruce Lee Coulter
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Abstract
A method and system of providing ultrapure water for semiconductor fabrication operations is provided. The water is treated by utilizing a free radical scavenging system and a free radical removal system. The free radical scavenging system can utilize actinic radiation with a free radical precursor compound, such as ammonium persulfate. The free radical removal system can comprise use of a reducing agent. The ultrapure water may be further treated by utilizing ion exchange media and degasification apparatus. A control system can be utilized to regulate addition of the precursor compound, the intensity of the actinic radiation, and addition of the reducing agent to the water.
Claims9
A method for measuring a concentration of persulfate and sulfur dioxide in an ultrapure water stream comprising:
- introducing persulfate to the ultrapure water stream having a TOC concentration of less than about 25 ppb;
- measuring a first conductivity of the ultrapure water stream in a first conductivity cell of a first sensor;
- irradiating the ultrapure water stream to provide an irradiated ultrapure water stream;
- measuring a second conductivity of the irradiated ultrapure water stream in a second conductivity cell of the first sensor;
- calculating the concentration of persulfate in the ultrapure water stream based in part on the first conductivity measurement and the second conductivity measurement of the first sensor;
- introducing sulfur dioxide to the irradiated ultrapure water stream;
- measuring a first conductivity of the irradiated ultrapure water stream comprising sulfur dioxide in a first conductivity cell of a second sensor;
- irradiating the ultrapure water stream comprising sulfur dioxide to provide an irradiated ultrapure water stream comprising sulfur dioxide;
- measuring a second conductivity of the irradiated ultrapure water stream comprising sulfur dioxide in a second conductivity cell of the second sensor;
- and
- calculating the concentration of sulfur dioxide in the irradiated ultrapure water stream comprising sulfur dioxide based in part on the first conductivity measurement and the second conductivity measurement of the ultrapure water stream comprising sulfur dioxide of the second sensor.
Dependencies are inferred from the claim text.