(28d) Novel Membranes, Membrane Separation Techniques and Technologies

There are numerous ongoing investigations in supposed frontiers in membranes and membrane separation technologies. In our laboratories we have been pursuing a few of them. This talk will identify the problems, the approaches we are studying and the membrane separation results being achieved. The problems involve thermal desalination methods, treating strongly oxidizing aqueous solutions, processing powerful organic solvent systems, and removing and recovering CO₂ from post combustion flue gas as well as precombustion syngas. In thermal desalination methods we will illustrate first our results on direct contact membrane distillation (DCMD) for temperatures between 50 to 130⁰C and operation with salt concentrations between 0.2- 20 wt%. In airgap membrane distillation (AGMD) we will next show how a two hollow-fiber-set based compact device can be a highly productive desalination device without any need for a cooling water stream to start with. We will next focus on the performances of a perfluoropolymer membrane having exceptional chemical and thermal resistance. This membrane can concentrate a very dilute aqueous solution of H₂O₂ to as much as 40% H₂O₂ by simple pervaporation under almost ambient conditions. Further this membrane can dehydrate powerful aprotic solvents such as DMF, DMSO, DMAc with selectivities in the range of 1000-12000 characteristic of zeolite membranes in dehydration of ethanol. We will conclude by describing two new techniques and the corresponding membranes/processes to remove CO₂ from flue gas or from hot precombustion syngas at a high pressure.