Time: Wednesday & Thursday, September 29th & 30th, 2:00 p.m.
Location: Aggarwal Lecture Hall, Room 130
Polymer Engineering Academic Center
250 South Forge Street, Akron, OH 44325-0301
Lectures Are Free And Open To The Public
Separation of common gas mixtures by polymeric membranes has been commercial for over 30 years and continues to grow as a low cost, energy efficient unit operation. An empirical correlation was noted 20 years ago which observed that common gas pairs (from the list of O2, N2, CO2, H2, He, CH4) exhibited an upper bound relationship with polymeric membranes. This upper bound was expressed as a line on a log-log plot of separation factor versus permeability of the more permeable gas above which virtually no data exists. The upper bound relationship was later derived from fundamental principles (by B. Freeman) offering theoretical justification. The structure-property characteristics of polymers offering upper bound performance will be discussed as well as commercial applications involving membrane separation of gases. The upper bound relationship is a function of temperature and a recent coauthored paper has predicted the temperature dependence based on fundamental relationships.
An additional correlation employing a large database of permeability values for the common gases yields a correlation: where Pi and Pj are the permeabilities of gases i and j chosen such that n>1.0. Linear behavior of the plots (log Pj versus log Pi) of all the possible gas pairs are observed over nine orders of magnitude implying that solution-diffusion behavior exists for all known polymeric membranes. The value of n correlates with the gas kinetic diameters; in agreement with theory. Additionally, the values of n can be employed to determine the kinetic diameters of these gases offering a more accurate set of data for gas diffusion in polymers than existing to date.
Potable water availability has been noted to be one of the key concerns of the 21st century. Polymeric membrane purification of water (reverse osmosis, nano-, ultra- and microfiltration, electrodialysis) has emerged as a primary method for recovery of purified water streams from brackish water, seawater, municipal and industrial waste water as well as utility in the food processing industry and biomedical applications. Desalination of brackish and sea water sources, once dominated by distillation, involves reverse osmosis as the primary process chosen for new installations. This is even true in areas of the world where waste energy or energy costs are very low cost (such as in the Middle East). If there is a dominant technology involving the future for clean water availability, it is clearly membrane technology. This tutorial lecture will detail the technology, applications, and fundamentals of water transport. A specific problem with wastewater recovery is concentration polarization (membrane fouling). The nature of concentration polarization and approaches to reduce this problem will be noted. The concept of forward osmosis to generate potable water from contaminated sources including seawater as well as generate electrical power will also be discussed. A primary topic will be the membrane fabrication technology employed for the various membrane processes utilized for water purification.
Lloyd M. Robeson received his BS degree in Chemical Engineering from Purdue University in 1964 and his PhD in Chemical Engineering from the University of Maryland in 1967. He was employed at Union Carbide Corporation from 1967 to 1986 and at Air Products and Chemicals, Inc. from 1986 to 2007, at which time he retired. His career in industry was primarily involved with polymer science and engineering. During his industrial career he worked in areas of polymer blends, and composites, permeability, engineering polymers, flame retardant polymers, thermoplastic polyurethanes, polyolefins and ethylene copolymers, environmental stress failure, biomedical applications, water soluble polymers, polymer processing, reactive extrusion, compatibilization, block and graft copolymers, adhesives, polymers for electronic applications, conducting polymers and membrane separation processes. He is a member of the National Academy of Engineering and is in the College of Engineering Innovation Hall of Fame at the University of Maryland.He has received Distinguished Alumnus Honors from both Purdue University and the University of Maryland. His publications number ~100 including two books on the subject of polymer blends. He is the (co)author of 100 US patents which have led into a number of commercial products. Presently, he is an Adjunct Professor at Lehigh University.