An Automated Experimental System for the Measurement of Membrane Transport Parameters Using Pulsed and Oscillatory Sources

[摘要] The development and use of membrane science and its related membrane processes have increased dramatically over the last twenty years or so. Although there has been a long history in the development of this field there remains a great deal more research and development to be done. One particular problem is in the testing and evaluation of new or modified membranes. Methods and methodologies for testing exist but they require the use of highly specific equipment and very highly skilled and knowledgeable operators in order to obtain data of any quality. Investigation of the fundamental transport properties has been conducted using concentration (or pressure) steps and oscillations in the source (feed side) and to monitor the resultant response of the test membrane in the collecting volume (down stream). By using such methods it suggested that after initial investigation, multiple determinations of the transport properties could be made within a single experiment. The construction and development of the hardware elements (measurement cells etc.) alone was insufficient to provide a routine method of testing. The methods used for the data analysis also required to be routine but still rigorous in their treatment of the experimental data. It was the combination of these two component parts that made the system both powerful and flexible. One of the objectives of this current work was to produce a measurement system which would be simple and flexible to operate and also allow semi-skilled personnel to obtain accurate and precise membrane transport data on a routine basis. A completely automated computer controlled system was designed and built in conjunction with membrane simulation software to optimise the measurement cell designs. The control hardware system was developed around a commercial modular interface system, Biodata MICROLINK. Using only the commercial device driver supplied, all of the necessary software for the control, display and processing of the experimental information was written specifically for the tasks at hand. Tvvo systems were developed around the same hardware/software configuration (a) a system for testing gaseous transport in membranes and (b) a system for liquid (solution) based transport. There is a substantial literature of gaseous transport in membrane systems, particularly using polymeric membranes. It was one of the main objectives of this work to study new porous ceramic membranes and to attempt to determine the transport properties of the thin active layers explicitly, both for gaseous and liquid based transport. The performance of the systems have been thouroughly tested to ensure that the generated step and oscillatory concentration waveforms are as close to ideal as practically possible. The performance of the systems have also been tested using model membrane systems to ensure the accuracy and precision of the transport data obtained for known systems prior to testing new ceramic membranes. This has been possible, as ceramic membranes are produced in a step by step fashion and by measurement at each stage in the preparation and at the final (composite) membrane stage, the effect due only to the active layer can be determined by the data analysis methods used. Using these measurement systems it has been possible for the first time to determine the transport properties of the active layer of a ceramic membrane both accurately and routinely. The systems are of course suitable for the testing of more conventional membrane types such as polymeric and charged membrane systems and examples of these are also given to show the general scope and application of the system. In conclusion, measurement systems have been produced that allow for the totally automated and repeated determination of the fundamental transport properties of membranes on a routine basis without the need for highly skilled personnel.

[发布机构] University:University of Glasgow

[关键词] Chemical engineering