In situ zeolite Na-X coating on glass fibers by soft solution process

A soft-solution process for in situ coating of faujasite type zeolite crystals on glass fibers was investigated. Commercial SiO2-Al2O3 glass fibers (SA fiber) and SiO2 glass fibers (SO fiber) were reacted at 60-150 degrees C for various times with NaOH solutions containing NaCl as a mineralizer. The surface of glass fibers was initially leached by the solution but after a certain time crystals of faujasite type zeolite precipitated on the fibers. Eventually the fiber surface was completely coated because of an increase in the concentrations of Si and Al in the solution due to dissolution of the fibers, especially the SO fibers. The important experimental parameters for formation of faujasite type zeolite were found to be the mixing ratio of SA fiber/SO fiber, the reaction time, NaOH concentration and the amount of added NaCl. The lattice constant of the resulting faujasite type zeolite identified it as zeolite Na-X with a Si/Al ratio of 1.28. (C) 2000 Elsevier Science B.V. All rights reserved.