Interaction and transformation of the mononuclear cationic dinitrosyl iron complex [Fe(SC(NH2)2)2(NO)2]+ (complex 1) upon binding with bovine serum albumin (BSA) have been explored using kinetic measurements, UV-Vis and fluorescence spectroscopy,...

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The material balance of water, phosphoric acid, and tri-n-butyl phosphate in the real process of purification of wet-process phosphoric acid by TBP extraction was studied. A process mechanism was suggested.One of the methods for purification of wet-process phosphoric acid (WPPA) is extraction with tri-n-butyl phosphate (TBP). At the Voskresensk Institute of Fertilizers and Phosphoric Acid, Joint-Stock Company, a pilot plant for production of purified phosphoric acid PPA from WPPA by tributyl phosphate (TBP) extraction in pulse columns have been operating for more than eight years. Its daily output capacity was brought to 50 355 tons of P 2 O 5 [2]. In this study, we examined the mechanism of water transfer with the extractant from the back-extraction column to the extraction stage. To our knowledge, there is no information on this mechanism in the literature. The process flowsheet is presented below. The material balance was determined from the process parameters measured during seven workdays. This balance appeared to be typical of extraction systems.Comparison of the sums of the input (G WPPA + G H 2 O ) and output (G raf + G pur. acid ) aqueous flow rates in the system reveals that the difference between them is 173.9 kg h !1 , the major part of the debalance (163 kg h !1 ) being accounted for by water. It follows from an analysis of the operation of the unit that this amount of water is evaporated from the column in the course of back extraction, since this stage is performed at 52355oC, which causes high water vapor pressure in the top part of the column.Furthermore, measurements of the WPPA input flow and raffinate flow output from the bottom of the extraction column show that the amount of water input to the column with WPPA (1455.1 kg h !1 ) is considerably smaller (by 321.7 kg h !1 ) than that removed from the column with the raffinate. As a result, a more dilute raffinate (26.89% recalculated for P 2 O 5 ) is formed instead of the estimated 30.3%.At the same time, in determining the rate of the water flow fed into to the column for back extraction, it was found that the amount of water entering the top part of the column (G H 2 O = 2980 kg h !1 ) exceeds by 484.7 kg h !1 that necessary for formation of 5447.3 kg h !1 of purified phosphoric acid. It was demonstrated that 163 kg h !1 is evaporated from the column. It is evident then that the remaining 321.7 kg h !1 should enter the first extraction column. Therefore, it follows from the analysis of the material balance that about 5% of water entering the column is evaporated from it, and the rest (about 11%) passes to the extraction stage and then is removed from the system with the raffinate flow.To verify this assumption, we analyzed the extract passing to back extraction, and also the extractant passing to the extraction column, for the content of water, using the Fischer titration method [GOST (State Standard) 14 870377]. Additionally, we analyzed the extract and extractant for H 3 PO 4 by potentiometric titration [3]. The results are listed in the ta...

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High molecular weight dinitrosyl iron complexes (DNICs) are formed in living systems and are a stable depot of nitrogen monoxide (NO). In this work, using experimental and theoretical methods, we...