Vibration Spectroscopy Stability Investigation of 12-Tungstosilicic Acid Solution
Abstract
Heteropoly acids (HPA) attract the attention of large variety of scientists, due to HPA's extraordinary interesting properties and possible application fields. 12-tungstosilicic acid (WSiA), the Keggin type HPA, has some promising characteristic to be used in catalytic processes, but with not well-defined stability. Raman spectroscopy was used for in situ analysis of WSiA hydrolysis in detail in a wide pH range of 1-12. Raman spectroscopy is able to give an almost immediate response/spectrum as a representation of the exact profile/composition of the solution. This method and FTIR spectroscopy, as a complementary technique, enabled recording of the solid and liquid phases of the same sample under different conditions. Our results confirm that the decomposition pathways of WSiA in solution proceed via the formation of the lacunary monovacant anion at pH > 6.4. This anion is a major constituent in pH range up to 9.5. With further increases in pH this species convert to the trivacant lacu...nary anion. The total decomposition of the Keggin anion to silicate and tungstate occurs at pH > 11.0. The results of the performed study contribute to understand the behavior of WSiA in the water-methanol solution, as the model system of aqueous-organic system. It is concluded that addition of methanol in aqueous solution of WSiA leads to expansion of the pH region where Keggin anion is stable up to 8.1 and above this pH value, precipitation occurs. The obtained data clarify the stability range of WSiA in both water and water-methanol solutions, as well.
Keywords:
12-Tungstosilicic acid / Raman spectroscopy / FTIR / Solvolytic stability / In situ reaction analysisSource:
Journal of the Iranian Chemical Society, 2015, 12, 1, 137-145Publisher:
- Springer, New York
Funding / projects:
- Electroconducting and redox-active polymers and oligomers: synthesis, structure, properties and applications (RS-MESTD-Basic Research (BR or ON)-172043)
DOI: 10.1007/s13738-014-0466-y
ISSN: 1735-207X
WoS: 000347416400016
Scopus: 2-s2.0-84920874366
Collections
Institution/Community
PharmacyTY - JOUR AU - Bajuk-Bogdanović, Danica AU - Uskoković-Marković, Snežana AU - Holclajtner-Antunović, Ivanka PY - 2015 UR - https://farfar.pharmacy.bg.ac.rs/handle/123456789/2378 AB - Heteropoly acids (HPA) attract the attention of large variety of scientists, due to HPA's extraordinary interesting properties and possible application fields. 12-tungstosilicic acid (WSiA), the Keggin type HPA, has some promising characteristic to be used in catalytic processes, but with not well-defined stability. Raman spectroscopy was used for in situ analysis of WSiA hydrolysis in detail in a wide pH range of 1-12. Raman spectroscopy is able to give an almost immediate response/spectrum as a representation of the exact profile/composition of the solution. This method and FTIR spectroscopy, as a complementary technique, enabled recording of the solid and liquid phases of the same sample under different conditions. Our results confirm that the decomposition pathways of WSiA in solution proceed via the formation of the lacunary monovacant anion at pH > 6.4. This anion is a major constituent in pH range up to 9.5. With further increases in pH this species convert to the trivacant lacunary anion. The total decomposition of the Keggin anion to silicate and tungstate occurs at pH > 11.0. The results of the performed study contribute to understand the behavior of WSiA in the water-methanol solution, as the model system of aqueous-organic system. It is concluded that addition of methanol in aqueous solution of WSiA leads to expansion of the pH region where Keggin anion is stable up to 8.1 and above this pH value, precipitation occurs. The obtained data clarify the stability range of WSiA in both water and water-methanol solutions, as well. PB - Springer, New York T2 - Journal of the Iranian Chemical Society T1 - Vibration Spectroscopy Stability Investigation of 12-Tungstosilicic Acid Solution VL - 12 IS - 1 SP - 137 EP - 145 DO - 10.1007/s13738-014-0466-y ER -
@article{ author = "Bajuk-Bogdanović, Danica and Uskoković-Marković, Snežana and Holclajtner-Antunović, Ivanka", year = "2015", abstract = "Heteropoly acids (HPA) attract the attention of large variety of scientists, due to HPA's extraordinary interesting properties and possible application fields. 12-tungstosilicic acid (WSiA), the Keggin type HPA, has some promising characteristic to be used in catalytic processes, but with not well-defined stability. Raman spectroscopy was used for in situ analysis of WSiA hydrolysis in detail in a wide pH range of 1-12. Raman spectroscopy is able to give an almost immediate response/spectrum as a representation of the exact profile/composition of the solution. This method and FTIR spectroscopy, as a complementary technique, enabled recording of the solid and liquid phases of the same sample under different conditions. Our results confirm that the decomposition pathways of WSiA in solution proceed via the formation of the lacunary monovacant anion at pH > 6.4. This anion is a major constituent in pH range up to 9.5. With further increases in pH this species convert to the trivacant lacunary anion. The total decomposition of the Keggin anion to silicate and tungstate occurs at pH > 11.0. The results of the performed study contribute to understand the behavior of WSiA in the water-methanol solution, as the model system of aqueous-organic system. It is concluded that addition of methanol in aqueous solution of WSiA leads to expansion of the pH region where Keggin anion is stable up to 8.1 and above this pH value, precipitation occurs. The obtained data clarify the stability range of WSiA in both water and water-methanol solutions, as well.", publisher = "Springer, New York", journal = "Journal of the Iranian Chemical Society", title = "Vibration Spectroscopy Stability Investigation of 12-Tungstosilicic Acid Solution", volume = "12", number = "1", pages = "137-145", doi = "10.1007/s13738-014-0466-y" }
Bajuk-Bogdanović, D., Uskoković-Marković, S.,& Holclajtner-Antunović, I.. (2015). Vibration Spectroscopy Stability Investigation of 12-Tungstosilicic Acid Solution. in Journal of the Iranian Chemical Society Springer, New York., 12(1), 137-145. https://doi.org/10.1007/s13738-014-0466-y
Bajuk-Bogdanović D, Uskoković-Marković S, Holclajtner-Antunović I. Vibration Spectroscopy Stability Investigation of 12-Tungstosilicic Acid Solution. in Journal of the Iranian Chemical Society. 2015;12(1):137-145. doi:10.1007/s13738-014-0466-y .
Bajuk-Bogdanović, Danica, Uskoković-Marković, Snežana, Holclajtner-Antunović, Ivanka, "Vibration Spectroscopy Stability Investigation of 12-Tungstosilicic Acid Solution" in Journal of the Iranian Chemical Society, 12, no. 1 (2015):137-145, https://doi.org/10.1007/s13738-014-0466-y . .