Rentgenska praškovna difrakcija mineralnih gnojil

Burg, Jerneja (author), Meden, Anton (mentor)

Mineralna gnojila so v današnji družbi bistvenega pomena, saj brez njih ne bi mogli zagotoviti dovolj hrane za celotno prebivalstvo. Ker na deklaracijah mineralnih gnojil ni na voljo podatka o tem, katere spojine jih sestavljajo, ampak le o elementih, ki jih vsebujejo, sem se odločila, da bom poskusila identificirati kristalne faze, ki jih vsebujejo, s pomočjo rentgenske praškovne difrakcije. Z uporabo računalniških programov sem analizirala difraktograme 18 vzorcev mineralnih gnojil. Kristalinične komponente sem določila s pomočjo programa Crystallographica Search-Match. Identificirala sem lahko spojine, ki so vir primarnih in sekundarnih hranil, spojin, ki so vir mikrohranil, pa večinoma nisem uspela identificirati, saj je bila njihova vsebnost pod mejo zaznave. Ugotovila sem, da sta v mojih vzorcih najpogosteje prisotni spojini amonijev dihidrogenfosfat in amonij-kalijev nitrat. Za pet vzorcev sem izvedla še kvantitativno analizo s programom Topas, ki uporablja metodo Rietveldovega prilagajanja. Z njim sem določila masne deleže identificiranih faz, ki sem jih nato preračunala na masne deleže hranil in primerjala z deklariranimi vsebnostmi. Pri dveh vzorcih je bilo ujemanje zadovoljivo, pri ostalih pa je prišlo do odstopanj. Vzrok so najverjetneje omejitve metode, saj ta upošteva le identificirane kristalinične komponente.

• Language: Slovenian
• Keywords: rentgenska praškovna difrakcija, mineralna gnojila, difraktogram, kvalitativna fazana analiza, kvantitativna fazna analiza
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2023
• PID: 20.500.12556/RUL-149563
• COBISS.SI-ID: 164592131
• Publication date in RUL: 07.09.2023

Secondary language

• Language: English
• Title: X-ray powder diffraction of mineral fertilizers

Abstract

Mineral fertilizers are crucial in today’s society because without them we would not be able to provide enough food for the entire population. Since the declarations on mineral fertilizers do not provide information about what compounds make up the fertilizers, but only the elements they contain, I decided to try to identify the crystalline phases they contain using X-ray powder diffraction. Using computer programs, I analysed diffractograms of 18 mineral fertilizers samples. The crystalline components were determined using Crystallographica Search-Match program. I was able to identify compounds that are sources of primary and secondary nutrients but failed to identify most of the compounds that are sources of micronutrients as their content was under detection limit. I discovered that the compounds most frequently present in my samples were ammonium dihydrogen phosphate and ammonium potassium nitrate. I also preformed a quantitative analysis for five samples with Topas program, which uses Rietveld refinement method. I used it to determine the mass fractions of the identified phases, which I then converted to nutrient mass fractions and compared them with the labelled contents. Two samples had satisfactory match but there were some deviations with the other samples. This is probably due to the limitations of the method since it only takes into account the identified crystalline components.

• Keywords: X-ray powder diffraction, mineral fertilizers, diffractogram, qualitative phase analysis, quantitative phase analysis