Fig. 9: Elemental mapping for Si (b), Al (c), and O (d) of the
cross-section, and the Si/Al ratio of the membrane surface (e) of the
M14 sample prepared in this work by EDAX spectrum quantification
technique
The EDX elemental mapping for Si, Al, and O of the cross-section and the
Si/Al ratios of the surface of the best ZSM-5 zeolite membrane prepared
in this work (M14 membrane) are shown in Fig. 9. It can be found from
Fig. 9 that the Si/Al ratio of the membrane surface reached 50,
reflecting that despite the low Si/Al ratio of initial synthesis
solution (⁓160) a part of the alumina from the support (as aluminate
ions) dissolves in the synthesis solution and is incorporated into the
framework of zeolite layer during the secondary growth method [22].
Nevertheless, as it is well known that the hydrophilicity of a zeolite
membrane strongly depends on the Si/Al ratio of zeolite layer, the ZSM-5
membranes prepared in this work still could be used for organic/water
separation process by pervaporation technique.