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. 2016 Mar 11:6:22734.
doi: 10.1038/srep22734.

GIS-NaP1 zeolite microspheres as potential water adsorption material: Influence of initial silica concentration on adsorptive and physical/topological properties

Pankaj Sharma  1 , Ju-Sub Song  1 , Moon Hee Han  1 , Churl-Hee Cho  1
Affiliations

GIS-NaP1 zeolite microspheres as potential water adsorption material: Influence of initial silica concentration on adsorptive and physical/topological properties

Pankaj Sharma et al. Sci Rep. .

Abstract

GIS-NaP1 zeolite samples were synthesized using seven different Si/Al ratios (5-11) of the hydrothermal reaction mixtures having chemical composition Al2O3:xSiO2:14Na2O:840H2O to study the impact of Si/Al molar ratio on the water vapour adsorption potential, phase purity, morphology and crystal size of as-synthesized GIS-NaP1 zeolite crystals. The X-ray diffraction (XRD) observations reveal that Si/Al ratio does not affect the phase purity of GIS-NaP1 zeolite samples as high purity GIS-NaP1 zeolite crystals were obtained from all Si/Al ratios. Contrary, Si/Al ratios have remarkable effect on the morphology, crystal size and porosity of GIS-NaP1 zeolite microspheres. Transmission electron microscopy (TEM) evaluations of individual GIS-NaP1 zeolite microsphere demonstrate the characteristic changes in the packaging/arrangement, shape and size of primary nano crystallites. Textural characterisation using water vapour adsorption/desorption, and nitrogen adsorption/desorption data of as-synthesized GIS-NaP1 zeolite predicts the existence of mix-pores i.e., microporous as well as mesoporous character. High water storage capacity 1727.5 cm(3) g(-1) (138.9 wt.%) has been found for as-synthesized GIS-NaP1 zeolite microsphere samples during water vapour adsorption studies. Further, the total water adsorption capacity values for P6 (1299.4 mg g(-1)) and P7 (1388.8 mg g(-1)) samples reveal that these two particular samples can absorb even more water than their own weights.

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Figures

Figure 1
Figure 1. XRD diffraction patterns of as-synthesized GIS-NaP1 zeolite microspheres and JCPDS file no. PDF#97-000-9550 data showing high phase purity of each sample.
Figure 2
Figure 2. SEM images of knobby surfaced, microspheres of as-synthesized GIS-NaP1 zeolite microspheres with different Si/Al ratio.
Figure 3
Figure 3. TEM images representing knobby surfaced microspheres and magnified view of nano crystallites of as-synthesized GIS-NaP1 zeolite crystals with different Si/Al ratio.
Figure 4
Figure 4. High magnification TEM images demonstrates that the Si/Al ratio affects the length and width of inter crystallite or intra microsphere void generated by the self-oriented arrangement of nano crystallite or mesoporosity of as-synthesized GIS-NaP1 zeolite crystals.
Figure 5
Figure 5. Curves representing the particle size distribution of as-synthesized GIS-NaP1 zeolite microspheres having different Si/Al ratio.
Figure 6
Figure 6. FTIR spectra of as-synthesized GIS-NaP1 zeolite microspheres having different Si/Al ratio.
Figure 7
Figure 7. Water vapour adsorption-desorption isotherms of GIS-NaP1 zeolite microspheres obtained from different Si/Al ratio precursors reaction mixture at 298 K, and GIS-NaP1 zeolite framework.
Figure 8
Figure 8. Graphs represent the water vapour adsorption-desorption isotherms of commercial LTA (3A, 4A and 5A), NaX, NaY, and self-synthesized (SS) LTA zeolite samples.
Figure 9
Figure 9. SEM images of commercial LTA (3A, 4A and 5A), NaX, NaY, and self-synthesized LTA zeolite crystals those used for comparative water vapour adsorption studies.
Figure 10
Figure 10. Comparison of water vapour uptake capacity of other hydrophilic porous zeolite materials and as-synthesized GIS-NaP1 zeolite samples in different pressure ranges (P/Po), and total water vapour adsorption capacities.
Figure 11
Figure 11. Water vapour adsorption HK and SF pore size distribution curves for GIS-NaP1 zeolite samples synthesized from different Si/Al ratio precursors reaction mixture.
Inset image indicates the existence of some smaller pores.
Figure 12
Figure 12. N2 gas adsorption-desorption isotherms of GIS-NaP1 zeolite microspheres obtained from different Si/Al ratio precursors reaction mixture at 77 K.
Figure 13
Figure 13. HK, SF, BJH, and DH pore size distribution curves obtained from N2 gas adsorption for GIS-NaP1 zeolite samples synthesized from different Si/Al ratio precursor’s reaction mixture.
Figure 14
Figure 14. NLDFT pore size distributions of the GIS-NaP1 zeolite samples derived from N2 adsorption isotherms.
Figure 15
Figure 15. Thermo-gravimetric analysis (TGA), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC) curves of the GIS-NaP1 zeolite samples using a temperature ramp of 10 °C min−1.
Figure 16
Figure 16. Graphical representation of multistep water vapour adsorption on micro-meso-macroporous GIS-NaP1 zeolite microsphere sample.
Figure 17
Figure 17. Pore size distributions of the GIS-NaP1 zeolite samples analysed by mercury intrusion porosimetry.
See this image and copyright information in PMC

References

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