Q&A with Charlie Hill
Professor Thatcher Root sat down recently to talk with Emeritus Professor Charlie Hill about his many professional accomplishments. The two share interests in teaching—especially summer lab, kinetics and reactor design, and catalysis.
You've collaborated a lot with people in other departments, even before it was common. How did you become interested in such different applications?
I had wide scientific interests as a student at MIT, and took a disproportionate number of physics and mathematics courses for a chemical engineering undergraduate. After I completed my ScD at MIT, which was only remotely related to any research I did subsequently, I served to the rank of captain in the Army and worked on problems of radioactive waste disposal at the U.S. Army Nuclear Defense Laboratory. We were concerned with how one could safely concentrate or fractionate radioactive liquid wastes. We worked primarily on devices for removing the vast majority of water from these radioactive solutions. This work involved use of reverse osmosis (RO), an emerging membrane separation technology.
When I came to the University of Wisconsin in fall 1967, I was approached by Norm Olsen and Clyde Amundsen, both professors of food science, who were interested in using membrane processes for concentrating the solids contained in the whey produced as a byproduct of cheese manufacture. We agreed to collaborate and looked first at the problem of merely concentrating the whey. This work with graduate student R.I. Fenton-May, laid the basis for a number of subsequent dairy and food related research efforts by my graduate students and my courtesy appointment as a professor of Food Science. During the course of Fenton's PhD research, ultra-filtration (UF) membranes became commercially available and this new technology opened up additional applications of membrane techniques for processing liquid whey. RO and UF could be employed alone or in combination to produce streams that differed in chemical composition and were thus suitable for various applications in the food industry. The whey protein concentrates were of particular interest to industry.
This opportunity to work on a food-related research problem was (like several of my collaborative research efforts) an exercise in serendipity in the sense that while I was recruited to UW for my expertise in chemical kinetics, my military service had prepared me to make contributions that would prove very useful to the dairy industry that is so important in Wisconsin. Other research at the interface between chemical engineering and food science involved hydrolysis of the lactose in dairy products using continuous flow immobilized enzyme reactors and enzymatic modification of milk fat to substitute beneficial fatty acid residues for the less than desirable saturated fatty acid residues present in naturally occurring milk fat.
The work of my research group in membrane separations also led to projects with biomedical applications, as well as work with collaborators at the USDA Forest Products Lab in Madison, and the UW Water Chemistry Program (now Environmental Chemistry and Technology). Opportunities to work in these research areas arose as a result of serendipitous personal encounters that were largely accidental, but my breadth of interests had prepared me to welcome chances to explore research problems of an interdisciplinary nature.
WOW --- opportunistic, and a lot of successes in a lot of areas. More generally, how has chemical engineering changed as a discipline over your career?
I don't think that the principles underlying the discipline of chemical engineering have changed significantly. Chemical engineers are interested in a wide variety of chemical transformations and separation techniques. All ChEs employ material and energy balances—I teach these as "Pavlovian responses one and two" when students are stumped by a challenging new problem. In chemical reactor design we also need a rate-law or rate-expression so we can size a reactor properly.
However, in my lifetime the computational tools we use have changed quite drastically from slide rules and mechanical calculators to personal and supercomputers. Instead of using empirical correlations, ChEs can employ complex computer simulations. Of necessity our students are expected to be highly computer literate and able to solve complex equations using a variety of engineering software packages. The computational tools have changed, but the fundamental approaches have not.
You were also heavily involved in summer lab. Ws that an emphasis of yours?
I enjoyed teaching the class and the one-on-one interactions with students, and I greatly enjoyed the opportunity to foster the international summer laboratory program. I have taught European sections of our summer lab course at University College London (five times), the University of Oviedo (northern Spain) (five times), and the Technical University of Vienna (once).
I believe that these courses provide very challenging experiences for the students but the benefits of the course are not as apparent as they become after the students have gained professional experience. They come to realize that summer lab is not really as forbidding as the prevailing mythology about the course indicates. We work the students hard, but they learn a lot and they come away much more mature professionally than they were before they had experienced the course.
The course helps them to develop their technical writing skills. More importantly, the course is a great confidence builder.
In Madison students can go from knowing nothing about a topic to a report in a space of ten days. In Europe students learn that they can thrive in a foreign environment and/or new situations, as well as that their studies at UW-Madison prepare them to compete very successfully against students educated at other schools.
Knowing all the students in your classes has been a big part of your approach. Why does this matter?
It matters because the students know that you're interested in them, and it provides a useful teaching tool to force the students to participate in class discussions via my use of the Socratic dialogue. I tell the students that I don't care if they give me a right answer or a wrong answer, and that we often learn more from a wrong answer to a question in class than we can learn from a proper answer. The important point is that the students must know that they are going to be asked for their best guestimate as to how we are going to proceed for a particular problem. This is why I teach them "Pavlovian response number one."
What do you think were your most important professional contributions?
My most important contribution was doing a superb job in teaching key undergraduate courses in chemical engineering, primarily chemical kinetics and reactor design, as well as thermodynamics. I greatly enjoyed the classroom teaching aspect of my career. More importantly, I was a voice for support of the undergraduate program during faculty meetings and discussions.
A second major contribution was participation in administrative activities of the department and the university. I served for roughly a quarter of a century on the department's graduate admissions committee. I served several tours of duty as associate chair and three years as chair of ChE.
A third major contribution is the textbook I wrote for use in the undergraduate course in Chemical Kinetics and Reactor Design and the concomitant effort that went into preparing fresh problems to illustrate particular points, yet serve to stimulate student interest and thinking about the diverse nature of chemical engineering activities.
Finally, I was engaged in interdisciplinary research long before it became popular to do so; these activities gave me a chance to go out and bring some ideas back to the department to demonstrate to our students that there is a lot of important work to be done at the interface between chemical engineering and other disciplines.
That brings us full circle in terms of my breadth of interests.