Synthesis, characterization and catalytic activity of transition metal ...

Cation exchange capacity (CEC)
The CEC was calculated as per the method reported in the literature [37]. The zeolite prepared has
high cation exchange capacity. The CEC of raw fly ash was found to be 0 meq/100g while that of
FAZ was estimated to be 457 meq/100g which is a high value when compared with literature [38,
39]. Zeolitisation of fly ash has gained considerable attention owing to the enormous increase in
cation exchange capacity.
Surface area and pore size distribution of fly ash zeolite
Typical Nitrogen adsorption isotherm along with the pore size distribution has been presented in
Fig.3. The adsorption/desorption isotherm of Nitrogen for FAZ represents Type I [40]. Since
adsorption increases within a range, it indicates a definite growth in the number of micropores,
which is one of the defining features of zeolitic materials.
Fig. 1. (a) BET isotherm linear plot (b) BJH desorption dA/dlog(D) Pore area
The inflection in the Nitrogen isotherm around P/P0= 0.8-1.0 becomes sharper indicating
narrower and uniform pore size distribution. The surface area and pore diameter have been
acquired from the Nitrogen adsorption isotherm data. A surface area of 21.2018 m 2 /g and pore
volume of 0.010818 cm 3 /g clearly indicates that the material has a high order pore system. On the
basis of the above mentioned data and in reference to the SEM images, it can be further
conjectured that the pores in the zeolites are uniform and can facilitate complexation in them. The
crystallinity of the zeolites is reflected by the high surface area of the zeolites [41].
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