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Treatment of Electroless Copper Waste Disposal by UV Oxidation

IP.com Disclosure Number: IPCOM000040553D
Original Publication Date: 1987-Nov-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 3 page(s) / 16K

Publishing Venue

IBM

Related People

Lee, JCB: AUTHOR

Abstract

Electroless copper plating baths are not treatable by conventional technology when being prepared for disposal. This is due to the presence of high metal concentrations and strong metal complexing agents. A method of treatment which involves ultraviolet (UV) light and a strong oxidizing agent (either 03 or H2O2) can be used to treat the copper waste stream, as described in this article. The copper waste stream (CWS) consists mainly of a solution containing about 12 gm/l of Rochelle Salt (sodium-potassium tartrate) as the complexing agent, 3 gm/l of copper iron, and lesser amounts of nickel and iron. The solution also contains 26 gm/1 of formaldehyde as another organic constituent.

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Treatment of Electroless Copper Waste Disposal by UV Oxidation

Electroless copper plating baths are not treatable by conventional technology when being prepared for disposal. This is due to the presence of high metal concentrations and strong metal complexing agents. A method of treatment which involves ultraviolet (UV) light and a strong oxidizing agent (either 03 or H2O2) can be used to treat the copper waste stream, as described in this article.

The copper waste stream (CWS) consists mainly of a solution containing about 12 gm/l of Rochelle Salt (sodium-potassium tartrate) as the complexing agent, 3 gm/l of copper iron, and lesser amounts of nickel and iron. The solution also contains 26 gm/1 of formaldehyde as another organic constituent. The objective of the treatability study was to evaluate both UV/ H2O2 and UV/O3 processes to assess whether either or both processes can cost-effectively reduce the total organic carbon (TOC) content of the CWS to less than 5 parts per million (ppm) and the formaldehyde concentration to less than 100 parts per billion (ppb). With copper and iron being present in significant concentrations, and the Rochelle Salt present in a high concentration, pretreatment would probably be needed prior to UV oxidation processing. The copper waste stream is comprised of a spent plating bath solution and the rinse tanks which follow the bath on a plating line. The plating bath and rinse tanks are plumbed to a bulk waste storage tank. The waste stream is transported off site in bulk tanker trucks to a commercial industrial waste treatment facility where it undergoes a series of treatments and the water discharged. The Rochelle Salt causes difficulties for waste treatment by complexing metals from a clarifier and piping system and carrying the metals into a plant outfall. Formaldehyde is also of concern since the treatment plant cannot effectively reduce the concentration and formaldehyde is unacceptable in the plant outfall. The objective of the treatability study of CWS was to treat the waste stream to acceptable levels of formaldehyde and TOC with UV- ozonation and UV/H2O2, with and without lime pretreatment. The average composition of the stream was: Formaldehyde 26,000 mg/1

Rochelle Salt 10,000 mg/1

Copper 3,010 mg/1

Iron 7.7 mg/1

Sodium 450 mg/1

pH 10.0 S.U. The goal of the testing was to reduce the formaldehyde to O100 ppb and the TOC to J5 ppm such that the resulting stream could be handled by the waste treatment facility.

The UV-oxidation reactor used in these tests was a 1.5-liter, cylindrical glass reactor with one 40-watt UV lamp enclosed within a quartz sheath located on the vertical axis of the reactor. All tests were conducted on a batch basis using prescribed and practical quantities of H2O2 or O3 for bracketed and reasonable reaction times. Because this water contains a high concentration of Rochelle Salt (sodium-potassium tartrate), it was concluded that tests with and without lime pretreatment...