Poskus določitve poteka termičnega razpada kalijevega bis(oksalato)kuprata(II) dihidrata s termogravimetrično analizo in komplementarnimi tehnikami

Grabec, Karin (avtor), Čelan Korošin, Nataša (mentor)

V svojem diplomskem delu sem raziskovala potek termičnega razpada koordinacijske spojine kalijevega bis(oksalato)kuprata(II) dihidrata (K$_2$[Cu(C$_2$O$_4$)$_2$].2H$_2$O) in vpliv temperature sinteze na strukturo nastalega produkta. Opravila sem paralelni sintezi, prva po skripta, kjer reaktante raztopimo v vroči vodi in ju nato združimo, druga pa je potekala pri konstantnih 90 °C. Produkta sintez sem nato s pomočjo TGA termično obdelala v atmosferi argona, da sem dobila vzorce intermediatov. Ti so bili pridobljeni pod enakimi pogoji s segrevanjem do 110 °C, 285 °C, 400 °C in 1000 °C. Vzorce sem karakterizirala s pomočjo termogravimetrične analize (TGA), termogravimetrične analize z masno spektroskopijo (TGA–MS), rentgenske praškovne difrakcije (XRPD) in Fourierjeve transformacijske infrardeče spektrometrije (FT-IR) ter titracije z raztopino KMnO$_4$. Na podlagi XRPD in FT-IR meritev sem potrdila strukturo koordinacijske spojine po končani sintezi in strukture intermediatov posameznih stopenj termične razgradnje. S TGA–MS sem potrdila razvoj H$_2$O, CO in CO$_2$, tehnika TGA pa mi je po opravljenih analizah z vsemi drugimi tehnikami omogočala predpostavko stehiometrije reakcij in intermediatov vsake stopnje razpada. Ugotovila sem, da v prvi stopnji poteče popolna dehidratacija, v sledečih pa razpad strukture koordinacijske spojine na oksalat, karbonat ter razne okside (CuO, Cu$_2$O, KO$_2$ in K$_2$O). Kot končni produkt termične razgradnje koordinacijske spojine pri 1300 °C pa glede na izgled preostanka in izgube mase predpostavim rdeč Cu$_2$O. Zadnjo stopnjo izgube mase pripisujem (nepopolni) sublimaciji taline K$_2$O. Prav tako sem ugotovila, da temperaturni pogoji sinteze nimajo vpliva na strukturo nastalega produkta. Tekom analize rezultatov meritev komplementarnih tehnik (XRPD, FT-IR) pa sem še naletela na problem rehidracije preostankov po termični analizi.

• Jezik: Slovenski jezik
• Ključne besede: (K$_2$[Cu(C$_2$O$_4$)$_2$].2H$_2$O), TGA, TGA–MS, XRPD, FT-IR
• Vrsta gradiva: Diplomsko delo/naloga
• Tipologija: 2.11 - Diplomsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2025
• PID: 20.500.12556/RUL-171203
• COBISS.SI-ID: 246343171
• Datum objave v RUL: 19.08.2025

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: An attempt to determine the thermal decomposition process of potassium bis(oxalato)cuprate(II) dihydrate through thermogravimetric analysis and complementary techniques

Izvleček

In my thesis, I researched the course of thermal decomposition of the potassium bis(oxalato)cuprate(II) dihydrate (K$_2$[Cu(C$_2$O$_4$)$_2$].2H$_2$O) coordination compound and the effect of synthesis temperature on the structure of the resulting product. I performed parallel syntheses, the first according to the script, where the reactants were dissolved in hot water and then combined, and the second was conducted at a constant 90 °C. I then used TGA to thermally treat the products in an argon atmosphere in order to obtain intermediate samples. These were acquired under the same conditions by heating to 110 °C, 285 °C, 400 °C, and 1000 °C. I characterized the samples using thermogravimetric analysis (TGA), thermogravimetric analysis with mass spectroscopy (TGA–MS), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FT-IR) and titration with KMnO$_4$ solution. Based on XRPD and FT-IR measurements, I confirmed the structure of the coordination compound after the completion of the synthesis and the structure of the intermediates of individual stages of thermal degradation. I confirmed the development of H$_2$O, CO and CO$_2$ using TGA–MS, and after performing analyses with all other techniques, TGA enabled me to hypothesize the stoichiometry of reactions and intermediates for each stage of decomposition. I found that complete dehydration occurs in the first stage, and in the following stages, the structure of the coordination compound breaks down into oxalate, carbonate, and various oxides (CuO, Cu$_2$O, KO$_2$ and K$_2$O). The final product of thermal decomposition of the coordination compound at 1300 °C, based on the appearance of the residue and the loss of mass, I assume to be Cu$_2$O. I attribute the last stage of mass loss to the (incomplete) sublimation of the K$_2$O melt. I also found that the temperature conditions of the synthesis have no effect on the structure of the resulting product. During the analysis of the results of complementary techniques (XRPD, FT-IR), I also encountered the problem of rehydration of residues after thermal analysis.

• Ključne besede: (K$_2$[Cu(C$_2$O$_4$)$_2$].2H$_2$O), TGA, TGA–MS, XRPD, FT-IR