Precipitate oxalate

Oxalates. Stable oxalates of Pu(III), Pu(IV), and Pu(VI) are known. However, only the Pu(III) and Pu(IV) oxalates are technologically important (30,147). Brilliant green plutonium(III) oxalate [56609-10-0] precipitates from nitric acid solutions containing Pu(III) ions upon addition of oxaUc acid or sodium oxalate. The composition of the precipitate isPu2(C20 2 10H2O. A homogeneous oxalate precipitation by hydrolysis of diethyl oxalate at... 

Figure 8.4 Scale-up of continuous calcium oxalate precipitation, volume mean size L43 (300 ml, 4.3 1 and 121 0.04 M, 7.5 min, id). (Zauner and Jones, 2000h)...

Figure 8.6 Mean particle for calcium oxalate precipitation after Zauner and Jones, 2000b)...

Brecevic, Lj. and Kralj, D., 1989. Factors influencing the distribution of hydrates in calcium oxalate precipitation. Journal of Crystal Growth, 97, 460M68. 

Jongen, N., Lemaitre, J., Bowen, P. and Hofmann, H., 1996. Oxalate precipitation using a new tubular plug flow reactor. In Proc. 5th World Congress of Chemical Engineering. San Diego (California), July 14-18 (New York American Institute of Chemical Engineers), Vol. V, pp. 2109-2111. 

The calcium carbonate precipitate was removed by filtration, and the filtered solution was found to contain 1,436 g of fructose as determined by optical rotation. A small amount of calcium bicarbonate was present as an impurity in solution and was removed by the addition of oxalic acid solution until a test for both calcium and oxalic acid was negative. The insoluble calcium oxalate precipitate was removed by filtration. 

A special technique was developed for rare-earth samples in which rapid hydration and carbonation occurred. The rare-earth oxalates were found to be more stable than the oxides and were used as sample material. In the rare-earth processing procedures that include an oxalate precipitate, the oxalate can be used as sample material. The advantages are that no diluent is required, weighing is eliminated, and recovery of the rare earths is simplified. 

The complete chemistry of plutonium 1 iquid-to-solid conversion processes, especially peroxide and oxalate precipitation, should be further studied. Research and development of direct thermal denitration methods should also be pursued. 

Los Alamos is processing a wide variety of residues, including Pu-Be neutron sources, polystyrene-Pu02-U02 blocks, incinerator ash, Pu-U alloys and oxides, Pu-Zr alloys and oxides, Pu-Np alloys and oxides, Pu-Th alloys and oxides, etc. Processes have been developed for these scrap items (see Figure 2), but we need to know more about Pu-Np separations Pu-Th separations oxalate precipitations for both plus 3 and plus 4 valences valence stabilization dissolution methods for high-fired impure oxides in-line alpha monitors to measure extremely low concentrations of Pu and Am in HNO3 solutions and solubility of various mixtures of Pu02 and UO2 under a variety of conditions. 

If the kidneys remove too many calcium ions from the blood, the equilibrium position in the kidneys shifts to the right. Solid calcium phosphate can form in the kidneys, producing kidney stones. Kidney stones, which are painful, can also form as the result of calcium oxalate precipitating in the kidneys. Precipitates of other compounds can affect different areas of the body gallstones in the gall bladder and gout in the joints are two examples. 

This kidney stone formed when potassium oxalate precipitated out of solution in a kidney. How can you predict whether a precipitate, such as potassium oxalate, will form in an aqueous solution ... 

This reaction shows calcium chloride reacting with oxalic acid to produce calcium oxalate and hydrochloric acid. The calcium oxalate is the kidney stone. Calcium oxalate precipitates out of the urine in the kidneys of all individuals. Normally, the solids formed are grain size and do not cause prob-... 

Fig. lc. Electronmicrograph of isolated sarcoplasmic reticulum membranes loaded with calcium oxalate46. The preparation was negatively stained with potassium phosphotungstate. Size and shape of the calcium oxalate precipitates differ considerably. Fine particles which are present on the surface of most vesicles are clearly visible. In all pictures the length of the bars measures 0.1 pm... 

Complexometric titration with EDTA is the usual winery procedure for determining calcium (4, 6, 22, 113), but atomic absorption spectrophotometry (51,53,112) and flame photometry and a rapid micro method based on oxalate precipitation (114) have been used successfully. 

Siemers, 1995 landfill leachate Bio-O UV-Bio (sequential) (UV not used) 1 BC (each, 3 chemical stages in parallel) (5 barabs) 36 200// 100-400 2.0-3.0 23 Mio. 41.7 pH-control impossible (dirty probe) heavy Ca-oxalate precipitation in reactors, tubes and pumps foaming polluted off-gas 03-catalyser... 

Weaver [44], in a series of studies, found that mandelic acid is specially selective for rare earths. The / value for a Sm—Nd mixture in oxalate precipitation is 1.4, and the value for mandelate is 3.8. A large P value of 14 was obtained for La—Nd mandelate. However, the rapidity and completeness of precipitation is dependent on the pH, temperature and concentration of both the rare earths and mandelic acid. 

Nitric Acid and Organic Matter. The use of the mixed acids to digest organic matter may result in explosions. Explosions with vegetable oil,19 milk, calcium oxalate precipitates from plants,21 rat carcasses,22 finely ground plant material,21 and animal tissues21 have been documented. 

There are a variety of routes described as wet chemical . For example an acid (HN03) solution of the metal nitrates is prepared and the oxalates precipitated by the addition of oxalic acid and ammonia, to control pH. Because of mixing on... 

If 89Sr is present, the 89Sr and 90Sr +90Y beta-particle counts will have to be resolved. This is done by counting the strontium oxalate precipitate at least... 

An improvement of the oxalate precipitation method for the preparation of LaSrCo perovskites has been reported recently by Chang and Weng [43]. By substitut-... 

The flow scheme of the process(17) is represented in Fig. 2. The required throughput rate of 5 kg Pu/day is obtained in a batch-type operation, where a 5 to 10% substoichometric oxalate precipitation is performed by adding solid oxalic acid to a 3 M HNO - 100 g/L Pu(NO3) 4 solution at 80°C in about 2 hours. Up to 95% of the Pu is precipitated as uniform crystals of 20 yum average size and filtered. After washing and calcination, the average analysis of this product shows less than 1000 ppm total metallic impurities. When evaporating the filtrate to about 5% of its original volume, nitric acid is recovered, and most of the oxalic acid is destroyed. This results from sump temperatures of up to 123°C and the presence of Pu(VI). 

The process sequence currently used for waste salts (except those containing aluminum for which no process currently exists) is shown in Figure 1. The process includes (1) dilute hydrochloric acid dissolution of residues (2) cation exchange to convert from the chloride to the nitrate system and to remove gross amounts of monovalent impurities (3) anion exchange separation of plutonium (4) oxalate precipitation of americium and (5) calcination of the oxalate at 600°C to yield americium oxide. 

A continuing problem with the cation exchange process as used in production operations is that it has not been sufficiently selective and therefore allows considerable carryover of the MSE salt constituents and impurities with the plutonium and americium. This isn t serious with plutonium since plutonium can be subsequently purified by anion exchange. For americium, however, the subsequent recovery process is oxalate precipitation which is less selective and carries some of the impurities into the final product. 

Of special interest was the removal of lead. Most lead was removed during the loading and first washing cycle, which indicates lead is being complexed by the chloride ion. This complex is currently being used to aid in the decontamination of lead in the oxalate precipitation process. 

Additional work in progress includes optimization of parameters affecting the oxalate precipitation step this includes determination of the chloride concentration required to solubilize lead the oxalate ion concentration required for maximum americium recovery with minimum impurity precipitation precipitate aging and hydrogen ion concentrations that will minimize americium solubility yet maximize impurity solubilization. 

Am TO OXALATE PRECIPITATE STRIP SCRUB BIDENTATE EFFLUENT TO WASTE TREATMENT... 

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