The esterification of geraniol with acetic acid in n-hexane was investigated. A commercial lipase preparation from Candida antarctica was used as catalyst. The equilibrium conversion (no water removal) was found to be 94% for the reaction of 0.1 M alcohol and 0.1 M acid in n-hexane at 30 degrees C. This was shown by both hydrolysis and esterification reactions. The activation energy of reaction over the temperature range 10 degrees to 50 degrees C was found to be 16 kJ/mol. The standard heat of reaction was -28 kJ/mol. Membrane pervaporation using a cellulose acetate/ceramic composite membrane was then employed for selective removal of water from the reaction mixture. The membrane was highly effective at removing water while retaining all reaction components. Negligible transport of the solvent n-hexane was observed. Water removal by pervaporation increased the reaction rate by approximately 150% and increased steady-state conversion to 100%.

A versatile and inexpensive microbatch crystallization apparatus with an integrated thermal gradient is introduced. The device is designed to fit onto automated microscope stages for timed image acquisition. The thermal gradient is established through an aluminum plate machined to house commercially available microplates with a standard 96-well footprint. The novelty of the design includes online monitoring of crystal growth without interfering with the established thermal gradient. The temperature stability and unidirectional temperature gradient were demonstrated. Hen egg white lysozyme (HEWL) was used as a model macromolecule to observe the effect of temperature variations on crystal habit and the number and size of crystals produced.

Static light scattering and multiwell microbatch crystallization experiments have been used to determine how apoferritin crystal growth kinetics and final crystal size depend on temperature, pH, and cadmium concentration. The experiments were conducted on a linear thermal gradient covering a range from 30 to 40°C. Crystal growth was monitored in situ under a microscope without disturbing the thermal environment. A dependence of apoferritin crystal formation and growth on temperature and cadmium concentration was observed. The range of cadmium concentrations that resulted in apoferritin crystal growth was evaluated and found to be consistent with the osmotic second virial coefficients determined via static light scattering. For the domain of conditions where apoferritin crystal formation occurred, the initial molar growth rate of apoferritin crystals increased linearly with temperature. It was observed that increasing cadmium concentration decreased the dependence of the final crystal size on temperature. The measured dependence of growth kinetics on temperature allowed the estimation of an activation energy for crystal growth. By comparing the value of this activation energy with that for nucleation (obtained from the literature), it became possible to explain the observation of larger, but fewer, apoferritin crystals at higher temperatures, which has also been reported in the literature for other proteins.