A Tribute to Norman N. Li

Abstract

Researchers in the fields of facilitated transport and liquid membranes owe much to Dr. Norman N. Li for his pioneering work on facilitated transport and the invention of liquid surfactant (emulsion) membrane technology when he was with Exxon Research and Engineering Company. A member of the National Academy of Engineering, Dr. Li became Chairman and President of NL Chemical Technology, Inc. after he recently retired as Director of Research and Technology at Allied Signal. Although his 30 year career has been spent entirely in industry, Dr. Li has an impressive record of publication. Dr. Li has also made important contributions to the profession through his participation in AIChE, ACS, and the North American Membrane Society. This chapter will highlight some of Dr. Li's accomplishments, briefly describe the liquid membrane technology he invented, and discuss commercial applications of the emulsion liquid membrane (ELM) and related technologies.In 1968 Dr. Norman N. Li invented a new separation technology known as the liquid surfactant or emulsion liquid membrane (7). This technique combined the conventional separation unit operations of extraction and stripping into a single process capable of extremely rapid separations and high selectivity. The emulsion liquid membrane (ELM) process technology is capable of separating an extremely wide variety of solutes from organics to metal ions for a very diverse set of applications including wastewater treatment, biotechnology, and hydrometallurgy. This chapter will briefly describe ELM technology and Dr. Li's contributions to the profession through his work in professional societies. Extensive, recent reviews of all aspects of ELM technology are available including theory, design, applications and economics (2-6).