Separation of urea adducts in the analysis of complex mineral fertilisers

Autor: Barbara Grzmil, Krzysztof Lubkowski, Marcin Sadłowski, Kinga Łuczka
Rok vydání: 2016
Předmět:
Zdroj: Chemical Papers. 70
ISSN: 1336-9075
0366-6352
DOI: 10.1515/chempap-2015-0187
Popis: An investigation of the analytical separation of free urea from its additive compounds with H3PO4, HNO3, CaSO4 and Ca(H2PO4)2, based on the solubility in butan-1-ol (n-butanol, n-BuOH), is reported. Several methods were tested in order to obtain the best leaching efficiency and solvent utilisation. The urea content was determined using the spectrophotometric method. A simple qualitative determination of urea was also performed using a special type of urea indicator-paper developed during the study. The phase composition of the examined materials was studied using an X-ray powder diffraction method. The urea adducts with phosphoric and nitric acid were found to be soluble in n-BuOH, in a similar way as with free urea. However, the solubility of the urea adducts with CaSO4 and Ca(H2PO4)2 differs from the solubility of free urea, affording an effective separation of these compounds. The solubility of free urea under defined experimental conditions was estimated to be (1.432 ± 0.043) g of urea in 100 cm of n-BuOH. The trace solubilities of urea bound in the adducts CaSO4 · 4CO(NH2)2 and Ca(H2PO4)2 · 4CO(NH2)2 were (8.28 ± 0.61) mg and (29.83 ± 0.63) mg of urea in 100 cm of n-BuOH, respectively. Partial decomposition of Ca(H2PO4)2 to CaHPO4 was observed during the leaching process.
Databáze: OpenAIRE
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