Recycling of waste sulfuric acid

Details Recycling of waste sulfuric acid Recycling of waste sulfuric acid

1993-12-15

1996-06-04

Niebling, John

Hazardous or toxic waste destruction or containment

Containment

Solidification, vitrification, or cementation

205770, A62D 300, C25B 122, C25B 100, C02F 146

Patent

active

055235182

ABSTRACT:
Sulfuric acid used in the process of fabricating semiconductor devices, etc., can be recycled to reduce the amount of sulfuric acid to be discarded. A sulfuric acid effluent is fed to an anode chamber of a sulfuric acid-concentrating electrolyzer partitioned by at least one cation exchange membrane to concentrate sulfuric acid and generate oxidizing substances, so that the sulfuric acid can be used at the step of using sulfuric acid, and, when the concentration of impurities built up in the system exceeds a certain level, a part of sulfuric acid in the system is fed to a unit for refining sulfuric acid, where the sulfuric acid is refined and whence the refined sulfuric acid is fed back to the system. According to this recycling process, it is possible to obtain sulfuric acid having high oxidizing power with no addition of an oxidizing substance such as hydrogen peroxide thereto.

REFERENCES:
patent: 4613416 (1986-09-01), Kau et al.
Grant, Hackh's Chemical Dictionary, 4th edition, 1969, p. 484.
Skidmore, Kathy, "Reprocess Chemicals at the Fab Line" Semiconductor International, Jul. 1988, pp. 64-68.

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