Fluorescence confocal optical microscopy (FCOM) was used to characterize MFI membranes made by secondary (seeded) growth. It is demonstrated that FCOM is a powerful tool for the non-destructive evaluation of zeolite membranes. This technique can provide two-dimensional, optical sections of the membranes with submicron resolution without physical damage to the sample. When contrasted with fluorescein-Na salt, it is shown that the grain boundary network in MFI membranes can be observed along the thickness of the membranes. Moreover, defects that do not propagate to the membrane surface and, therefore, are not detected by SEM, can be clearly imaged. One example of such a defect are internal cracks in the membrane.
Bibliographical noteFunding Information:
M.T. and D.G.V. acknowledge support from the National Science Foundation (CAREER,CTS-9612485 and CAREER, CTS-9702615) and from NASA-microgravity (HRS-98). M.T. is grateful to David and Lucille Packard Foundation for a Fellowship in Science and Engineering and to the Camille and Henry Dreyfus Foundation for a Teacher-Scholar Award. G.B. is thankful for the financial support awarded from a GE Fund Fellowship and an Opportunity Fellowship from the University of Massachusetts. We also acknowledge the Central Microscopy Facility at the University of Massachusetts for use of its confocal microscopy facilities. M.T. is grateful to Dr. E. Kokkoli for helpful suggestions and assistance in experiments at the initial stages of this work.
- Confocal microscopy
- Inorganic membranes
- Zeolite membranes