TMAH with KI Has High Toxicity – Effluent from Semiconductor Factories

October 08, 2014

The collaborative research group of Okayama University, Kitakyushu City College and Universiti Kebangsaan Malaysia has revealed when tetramethylammonium hydroxide (TMAH) coexists with potassium iodide (KI), their toxicity together becomes three times as strong as the toxicity of each when they exist independently.

The findings will be published in February 2015 in the journal Chemosphere.

TMAH is used in high volume as an etching fluid in the process of semiconductor production and is subsequently released into rivers. The research group assessed the effect of TMAH on the stream's ecosystem. The results showed that TMAH has no toxicity to bacterium (vibrio) and green algae (Pseudokirchneriella subcapitata), but is toxic to fish (Oryzias) and Daphnia magna.

KI is also used in semiconductor production factories. The group also investigated in detail the toxicity of TMAH with KI to Daphnia. The result was that the toxicity of TMAH with KI is three times stronger than the toxicity of either of them alone. Coexistence of TMAH with KI exhibits a synergistic effect. The mechanisms of the synergistic effect are as of yet unclear.

Multiple chemical compounds are often released at the same time from factories after effluent treatment. In cases like TMAH and KI, the toxicity of combinations of chemicals could become stronger than that of individual ones. The findings are expected to lead to the development of new eco-friendly technologies for the effluent treatment of semiconductor factories.


Contact Information:
Mototaka Senda, Ph.D.
US Representative
Intellectual Property Office, Organization for Research Promotion and Collaboration, Okayama University
Fremont, California USA
TEL: 1-510-797-0907
Email: takasenda@okayama-u.ac.jp

Izumi Mori, Ph.D.
Institute of Plant Science and Resources, Okayama University, Okayama Japan