Extractants nitrates

An interesting application of this region of the spectrum is the determination of nitrate and nitrite in soil extracts. Nitrate is very soluble in water and can be extracted using a simple water extraction procedure. Nitrate absorbs at 210 nm and nitrite at 355 nm, and both can be quantified using these absorption maxima ( max). Other materials extracted from soil, as noted previously, however, can obscure this region, and thus caution must be exercised to determine if there are any interfering components in such extracts [6-10],... 

Duke, S.H. Duke, S.O. (1984). Light control of extractable nitrate reductase activity in higher plants. Physiologia Plantarum 62, 485-93. 

Iindau and Spalding [21] have studied the effects of 2 M potassium chloride extractant ratios of between 1 1 to 1 10 on nitrate recovery in nitrate and nitrite extractions from soil. Preliminary data indicated that concentrations of extractable nitrate and nitrogen isotopic values were influenced by the volume of extractant. The 1 1 extractions showed decreasing nitrogen isotope values with increasing nitrate levels, whereas in the 1 10 extractions these values were independent of each other. Incomplete extraction occurred for the 1 1 ratios. The ratio required for maximal recovery was not determined. 

Dual-host approaches have also been used to good effect for CsN03 extraction. Nitrate is a common anion found upon nitric acid extraction of 137Cs+ in the nuclear industry. Cs+ is conveniently com plexed by a large crown ether such as tetrabenzo[24] crown-8 while simple tripodal amide hosts of type 5.31 (where R is a long alkyl group to impart lipophilicity) are effective at binding N03 . Extraction efficiency of Cs+ from water into 1,2-dichloroethane was found to be enhanced by a factor of up to 4.4 in the presence of the anion host.28... 

To find a more effective means of employing gas on the battlefield, the German High Command turned to Professor Fritz Haber, the world-famous chemist who had developed a crucial process for extracting nitrates from the atmosphere (Nitrogen Fixation). This process was used... 

Principle of Separation. Uranium forms a nitrate complex that is extractable into ethyl acetate (as well as other organic extractants). Thorium does not readily form an extractable nitrate complex. When ethyl acetate is contacted with an aqueous solution, the uranium-nitrate complex is partitioned favorably into the ethyl acetate whereas thorium nitrate is not. The distribution of the metal ion between the two phases is expressed as D = Corganic/Caqueous where C is the concentration in moles or dps per unit volume in the respective phases. The thorium remains in the aqueous phase and is precipitated as the hydroxide for counting. 

Many operations in chemical engineering require the contact of two liquid phases between which mass and heat transfer with reaction occurs. Examples are hydrometallurgical solvent extraction, nitrations and halogenations of hydrocarbons, hydrodesulfurization of crude stocks, emulsion polymerizations, hydrocarbon fermentations for single-cell proteins, glycerolysis of fats, and phase-transfer catalytic reactions. A most common method of bringing about the contact of the two phases is to disperse droplets of one within the other by mechanical agitation. 

TBP can be decomposed explosively when heated to above 120°C in the presence of extractable nitrates [S4]. 

Silva et al.[44] developed an indirect Fl-AAS method for the determination of nitrate and nitrite in meats and vegetables following liquid-liquid extraction. Nitrate forms an ion pair with bis(2,9- dimethyl-l,10-phenanthrolinato)copper(l) which is extracted into IBMK. Copper is then determined in the separated mganic phase. When the nitrite is oxidized by cerium(VI) into nitrate before the extractirm, total nitrate is determined. When nitrite is ccmverted to nitrogen with sulfamic acid, only the origina] nitrate is determined. 

The dependence of the level of extractable nitrate reductase activity in... 

Am(vi) forms an extractable nitrate. Strong oxidizing conditions are neceBSSU y, however, for americium to be present in the (VI)-state. It is generally found In solution as Am(lll). 

The process produced a mixture of calcium and potassium nitrates, which were scraped off the piles after about two years and extracted with water. K2CO3 was added to the extracted nitrates, calcium and magnesium salts were separated from the solution, and evaporation and crystallization yielded nearly pure KNO3. The yields for properly managed nitrieres were around 5 kg KNOa/m in two years see Brunborg, L, and P. B. Holmesland. 1985. The history of nitric acid. In C. Keleti, ed.. Nitric Acid and Fertilizer Nitrates. New York Marcel Dekker, pp. 4-5. 

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