Novel membrane separations in biotechnology.

Membrane processes have great potential in biotechnology. This study was an attempt to investigate ways in which greater novelty could be achieved. One of the advantages of ultrafiltration for the separation of proteins is the comparatively mild conditions used. Various parameters were considered when operating a crossflow filtration system containing polysulphide membranes. A key operational parameter in such a system is the temperature utilised for the process. There are conflicting demands when selecting an operating temperature between the fluid dynamics and the biochemical properties of the system. An analysis of this conflict, in order to establish the optimal temperature, involved a model crossflow filtration system, where shear rate, volume of protein containing solution and protein concentration can be kept constant and only the temperature varied. In such studies denaturation of the permeate was observed and an optimal operating temperature was observed between 30 and 40 °C.

A supported liquid membrane system was investigated for the carrier mediated transport of phenylalanine to more fully understand the contradictory effects, described in the literature, of chloride ion concentration in the aqueous phases on the stability of the system. Various parameters were considered to optimise transport and stability. The role of the organic phase and its interaction with carrier and support material was also considered. The carrier mediated transport was comparable to an enzyme mediated process. Kinetic studies were undertaken and the data interpreted in a manner appropriate to biological transport processes to consider the transport process at a molecular level. The system was shown to deviate from a direct 1 : 1 exchange process between phenylalanine and chloride and had a high degree of selectivity with respect to phenylalanine.