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Featured Faculty: Keith Lodge

Associate Professor, Department of Chemical Engineering

Interests: Thermodynamics, Physical Chemistry & Particle Technology in Chemical, Environmental Engineering & Science, Partition Coefficients & Activity Coefficients

Courses Taught: Process Dynamics & Control (ChE4402), Heat & Mass Transfer (ChE3112), Principles of Particle Technology (ChE3241), Chemical Reaction Engineering (ChE4301) and Thermodynamics (ChE3211)

Website: http://www.d.umn.edu/~klodge/

Figure 1

The approach to steady-state: Toluene between air
and water at 25°C. Toluene, 0.100 mL/hr, and air,
40 sccm were allowed to flow over the water. The
data were fitted to a first-order model; the time
constant is 740 s.

The art of designing direct experiments is key in science and engineering; this fascinates Lodge and so attempts to practice this are reflected in his research.

Distribution coefficients are important across chemical engineering, physical, pharmaceutical and environmental chemistry. He designed a direct method of measurement for solutes containing chromophores distributed between gas and liquid phases1. Its primary advantage is the final equilibrium state can be clearly determined; this depends on feeding the headspace above the liquid with a gas mixture of predetermined solute composition (Fig.1).

Octanol-water partition coefficients (Kow) are significant for hazard and risk assessment as well as for designing pharmaceuticals. Separate measurements for key lipophilic solutes (log Kow>5.5) often lead to order-of-magnitude discrepancies in the values of log Kow; this poses difficulties for regulators, who depend on reliable values. Lodge’s detailed experiments with toluene over a wide range of composition (Fig. 2) led to an explanation. He interpreted the behavior by invoking association of solute both in the water and the octanol2. Association, if present, will increase with the solute’s lipophilicity and will result in the order-of-magnitude effects. In water this is a manifestation of the "hydrophobic effect".

Figure 2

Properties are important in understanding the behavior of materials in processes. The initial rate of reduction of taconite to elemental iron in the blast furnace depends upon the surface area available within the pellet to adsorption by the reducing gases.

 

Figure 3

Silhouettes were recorded upon
rotation of the pellet. The peri-
meters’ c oordinates were
extracted; from these the envelope
volume was calculated - this
analysis was done with MathCad.

Porosity is one measure of this. The support of the Natural Resources Research Institute enabled Lodge to adapt the "method of silhouettes" (Fig. 3) to measure the envelope volume of individual pellets; this is necessary to determine the pellet’s porosity3.

Lodge’s fascination with direct experiments has helped him setup two undergraduate labs that he regards as novel in chemical engineering education. The labs in "Principles of Particle Technology" (ChE3241) comprise simple experiments that reflect the natural development of the subject. In Process Dynamics & Control (ChE4402), students learn to program a microcontroller, which they then use to control a liquid-level in a tank; this requires most of the principles taught in class.

Dame Judi Dench4 provides a pithy modus operandi; Lodge tries to take his work seriously but not himself. His claim to ride the oldest bike on campus remains un­challenged. Other "green" activities include the nurturing of humulus lupulus, ribes nigrum and a compost heap in the back yard.

References
(1) Lodge, K. B.; Danso, D. Fluid Phase Equilib. 2007, 253, 74-79.
(2) Lodge, K. B.; Egyepong, E. J. J. Phys. Chem. A 2010, 114, 5132-5140.
(3) Lodge, K. B. Powder Technol. 2010, 204, 167-172.
(4) Barnes, B. "Taking Her Art Seriously, Not Herself". NYT, Feb. 14, 2011.