Effect of pH and Hydrogen Peroxide on Ozonic Decomposition of NCW-1001
Advancing the chemical engineering fundamentals
Chemical Reaction Engineering (T2-2P)
Keywords: Ozonic decomposition, NCW-1001, pH, Hydrogen Peroxide, Bubble Column
Polyoxyalkylene alkyl ether (NCW-1001) is a non-ionic surfactant and widely used in order to clean wafers in the Electronics Industry. Therefore much waste water of used ultra pure water containing NCW-1001 is produced in the Electronics Industry. To keep clean environment and water resources, recycle of the waste water is essential.
In order to recycle the waste water, it is necessary to remove surfactants such as NCW-1001. Ozonic decomposition and adsorption by active carbon are often used to remove surfactants. Active carbon is a very good adsorber, however, has a little capacity of adsorption. Therefore ozonic decomposition is done before adsorption by active carbon.
The rate of ozonic decomposition of NCW-1001 depends on gas velocity, ozonic concentration, temperature, liquid and gas properties, and geometry of reactors. In this work, the effect of pH on ozonic decomposition of NCW-1001 was experimentally studied.
A bubble column was used as a reactor. Its diameter and height were 0.16 m and 1.0 m, respectively. A perforated plate was used as a gas sparger. Oxygen from a cylinder was used as a gas. Ozone was generated by the ozone generator (PO-10 by Fuji Electric ). Ultra pure water by Nomura Micro Science was used as a liquid. NCW-1001 by Wako Chemicals was used as a surfactant. The experimental conditions were in the range of QG=2L/min, C=20ppm, pH=7-11 and H2O2=0-20ppm. QG and C mean flow rate of oxygen and concentration of ozone gas, respectively.
In case of no Hydrogen Peroxide, Rd and Ro increased in the range of pH=8-9, because OH radicals increased ozonic oxidation of NCW-1001. In the range of pH=10-11, Ro increased remarkably, however, Rd became smaller than that in the range of pH=7-9. The ozone was not used for decomposition of NCW-1001,but for reaction with strong base. Rd and Ro mean decomposition rate of NCW-1001 and ozonic consumption rate, respectively.
In case of addition of Hydrogen Peroxide, Rd and Ro increased remarkably in the rage of pH=7-9. But in the range of pH=10-11, Rd did not increase, though Ro increased remarkably.
See the full pdf manuscript of the abstract.
Presented Tuesday 18, 13:30 to 15:00, in session Chemical Reaction Engineering (T2-2P).
