Thermal kinetics and thermodynamics of the dehydration reaction of Mg3(PO4)2·22H2O

Abstract

Mg₃(PO₄)₂·22H₂O lost its crystal water in the temperature range of 40 - 200°C and the calcined sample was identified as Mg₃(PO₄)₂, was a notable for its further treatments in optical and electrical applications. Dehydration process was studied using non-isothermal thermogravimetry (TG) applying model-fitting method. Different mechanism models (chemical reaction order, diffusion and phase interfacial reaction) were applied. The activation energies calculated for the dehydration reaction; and average of activation energy was found as 160 kJ/mol.  The better kinetic model of the dehydration reaction for Mg₃(PO₄)₂·22H₂O was selected as F3 (chemical reaction - third order). The thermodynamic functions (ΔH, ΔG and ΔS) of the dehydration reaction were calculated by the activated complex theory and found that the process was endothermic, non-spontaneous and fast.

Keywords

• Magnesium phosphate,decomposition kinetic,thermal behaviour,thermodynamic

References

1. Aramendia MA, Borau V, Jimenez C, Marinas JM, Romero FJ 1999. Synthesis and characterization of magnesium phosphates and their catalytic properties in the conversion of 2-hexanol. Journal of Colloid and Interface Science, 217: 288–298.
2. Assaaoudi H, Fang Z, Butler IS, Ryan DH, Kozinski JA 2007. Characterization of a new magnesium hydrogen orthophosphate salt, Mg3.5H2(PO4)3, synthesized in supercritical water. Solid State Sciences 9: 385 – 393.
3. Boonchom B 2008. Kinetics and Thermodynamic Properties of the Thermal Decomposition of Manganese Dihydrogenphosphate Dihydrate. Journal of Chemical Engineering Data, 53: 1533–1538.
4. Boonchom B 2009. Kinetic and thermodynamic studies of MgHPO4·3H2O by non-isothermal decomposition data. Journal of Thermal Analysis and Calorimetry, 98: 863–871.
5. Boonchom B, Danvirutai C 2008. A simple synthesis and thermal decomposition kinetics of MnHPO4·H2O rod-like microparticles obtained by spontaneous precipitation route. Journal Of Optoelectronics And Advanced Materials, 10(3): 492 – 499.
6. Boonchom B, Puttawong S 2010. Thermodynamics and kinetics of the dehydration reaction of FePO42H2O, Physica B, 405: 2350–2355.
7. Debnath S, Saxena SK, Nagabhatla V 2016. Facile synthesis of crystalline nanoporous Mg3(PO4)2 and its application to aerobic oxidation of alcohols. Catalysis Communications 84: 129–133.
8. Gopinath P, Ramalingam V, Breslow R 2015. Magnesium pyrophosphates in enzyme mimics of nucleotide synthases and kinases and in their prebiotic chemistry. Proceedings of the National Academy of Sciences of the United Sciences, 112(39): 12011–12014.

9. Kanazawa T, Umegaki T, Shimizu M 1979. The synthesis of Mg3(PO4)2·8H2O and its polymorphism. Bulletin of the Chemical Society of Japan, 52(12): 3713–3717.
10. Kongshaug KO, Fjellvag H, Lillerud 2001. The synthesis and crystal structure of a hydrated magnesium phosphate Mg3(PO4)2·4H2O. Solid State Sciences, 3: 353–360.
11. Lopez FA, Tayibi H, Diaz IG, Alguacil FJ 2015. Thermal dehydration kinetics of phosphogypsum. Materiales de Construction, 65(319): 1-14.
12. Lu X, Chen B 2016. Experimental study of magnesium phosphate cements modified by metakaolin. Construction and Building Materials, 123: 719–726.
13. Mousa S 2010. Study on synthesis of magnesium phosphate materials. Phosphorus Research Bulletin, 24: 16 – 21.
14. Naqvi SR, Tariq R, Hameed Z, Ali I, Naqvi M, Chen WH, Ceylan S, Rashid H, Ahmad J, Taqvi SA, Shahbaz M 2018. Pyrolysis of high ash sewage sludge: kinetics and thermodynamic analysis using Coats-Redfern method, Renewable Energy, (In Press) doi: 10.1016/j.renene.2018.07.094
15. Pokorny P, Tej P, Szelag P 2016. Discussion about magnesium phosphating. Metalurgija, 55(3): 507–510.Qiao F, Chau CK, Li Z 2010. Property evaluation of magnesium phosphate cement mortar as patch repair material. Construction and Building Materials, 24: 695–700.
16. Rouzic M, Chaussadent T, Platret G, Stefan L 2017. Mechanisms of k-struvite formation in magnesium phosphate cements. Cement and Concrete Research, 91: 117–122.
17. Sadiq M, Abdennouri M, Barka N, Baalala M, Lamonier C, Bensitel M 2015. Influence of the Crystal Phase of Magnesium Phosphates Catalysts on the Skeletal Isomerization of 3,3-dimethylbut-1-ene. Canadian Chemical Transactions, 3(2): 225–233.
18. Sadiq M, Bensitel M, Lamonier C, Leglise J 2008. Influence of the nature of precipitating basic agent on the synthesis of catalytic magnesium phosphate materials. Solid State Sciences, 10: 434–437.
19. Sronsri C, Boonchom B 2018. Determination of thermokinetic parameters and thermodynamic functions from thermoforming of LiMnPO4. Journal of Thermal Analysis and Calorimetry, 134(3): 1575 – 1587.
20. Wu F, Wei J, Guo H, Chen F, Hong H, Liu C 2008. Self-setting bioactive calcium–magnesium phosphate cement with high strength and degradability for bone regeneration. Acta Biomaterialia, 4: 1873–1884.
21. Yang Q, Zhu B, Wu X 2000. Characteristics and durability test of magnesium phosphate cement-based material for rapid repair of concrete. Materials and Structures, 33: 229–234.
22. Yu C, Wu Q, Yang J 2017. Effect of seawater for mixing on properties of potassium magnesium phosphate cement paste. Construction and Building Materials, 155: 217–227.
23. Yu X, Jiang J 2018. Mineralization and cementing properties of bio-carbonate cement, bio-phosphate cement, and bio-carbonate/phosphate cement: a review. Environmental Science and Pollution Research, 25: 21483–21497.
24. Yu XN, Qian CX, Sun LZ 2016. Chemosynthesis of nano-magnesium phosphates and its characterization. Digest Journal of Nanomaterials and Biostructures, 11(4): 1099–1103.
25. Zhang S, Li L, Lv X 2016. Synthesis and characterization of a novel Mg3(PO4)2 ceramic with low dielectric constant. Journal of Materials Science: Materials in Electronics, DOI: 10.1007/s10854-016-5703-y
26. Zhang Z, Tang W 2015. Tunable Blue–Red Emission and Energy-Transfer Properties of Mg3(PO4)2:Eu2+,Mn2+ Phosphors. Eyropen Journal of Inorganic Chemistry, 2015: 3940–3948.
27. Zhou H. Luchini TJF, Bhaduri SB 2012. Microwave assisted synthesis of amorphous magnesium phosphate nanospheres. Journal of Materials Science: Materials in Medicine, 23:2831–2837.