Magnesium precipitation method

Diverse thermogravimetric results can be obtained from samples with different pre-histories for example, TG and DTG curves showed that magnesium hydroxide prepared by precipitation methods has a different temperature of decomposition from that for the naturally occurring material.32 It follows that the source and/or the method of formation of the sample should be ascertained. 

If polymerization catalysts, for instance for alkenc polymerization (Zicglcr-Natta-type catalysts), are prepared by precipitation methods, they can be formed by precipitation from organic solvents, as claimed in several patents [22], In these patents the precipitation of titanium-magnesium compounds in THF with hexane as precipitating agent is used for the formation of the catalyst. Many important Zicgler-Natta initiators are solids, and heterogeneous initiator systems seem to be necessary for the production of isotactic polyalkenes [23]. However, not much information on the details of catalyst preparation is available in the open literature. 

To calculate the soda ash requirement for the calcium noncarbonate hardness by-product, let M gca represent the mass of the magnesium species that precipitates and results in the production of the additional calcium hardness cation, where the Ca, again, is written as a reminder. Refer to Eqs. (10.17), (10.18), and (10.19) to see how the calcium hardness is produced from the precipitation of noncarbonate magnesium. The number of equivalents of the calcium hardness produced is equal to the number of equivalents of the noncarbonate hardness of magnesium precipitated [which is equal to MMgCa/(Mg/2), where Mg/2 is the equivalent mass of Mg as obtained from Eqs. (10.17), (10.18), and (10.19)]. Because this is calcium hardness, we aheady have the method of determining the amount of soda ash needed to remove it as shown in Equation (10.25). Letting this amount be is... 

Dawson and Heaton (DIO) determined magnesium in plasma and urine. A water-cooled burner was used with an air-acetylene flame. Good agreement was found with an ammonium phosphate precipitation method when allowance was made for the loss of magnesium during precipitation. 

Acidification of aqueous concentrates and extracts to pH near 1 is the standard procedure to precipitate humic from fulvic acid, and this procedure also has been applied to aquatic humic substances (Thurman and Malcolm, 1981). Aquatic humic substances that interact significantly with metal ions can be precipitated from water by addition of lead(Il) nitrate (Klocking and Mucke, 1969). Co-precipitation of aquatic humic materials with aluminum, copper, iron, and magnesium hydroxides has been used to recover aquatic humic substances from various types of water (Jeffrey and Hood, 1958 Williams and Zirino, 1964 Zeichmann, 1976). Humic acids can also be precipitated from an unconcentrated water sample by adding acetic acid and isoamyl alcohol to a sample contained in a separatory funnel, and after shaking, humic acid precipitates at the alcohol-water interface (Martin and Pierce, 1971). Precipitation methods are among the crudest of fractionation methods... 

The literature contains numerous examples of the use of hydroxides as coprecipitants of trace metals because the hydroxides are easily produced, very flocculant, and capable of removing both ionic and nonionic species from solution due to their large surface area. Sodium, calcium, and magnesium are not generally recovered to any extent which makes the method useful for seawater samples. One difficulty with any precipitation method is the extensive time required for a careful precipitation and filtration. 

Add a saturated solution of sodium bicarbonate to neutralize. Pour the mixture into brine and extract with methylene chloride (3 x 50 mL). Combine the organic fractions and dry over magnesium sulfate. Remove the dessicant and concentrate to approx 5 mL. The polymer was then removed by the standard precipitation method (see Note 7). 

In this work, the primary objective is to study the phase stability and sinterability of synthesized HA ceramics by wet precipitation method when doped with up to 1 wt% magnesium oxide (MgO) via a new profile for conventional pressureless sintering. 

Magnesium haUde and alkyl magnesium haUde precipitate and the alkyl magnesium compound remains in solution. Filtration (qv) followed by drying the filtrate yields soHd magnesium alkyl (11). Another preparation method is that of metal exchange using mercury alkyl in ether. 

Discussion. Some of the details of this method have already been given in Section 11.11(C), This procedure separates aluminium from beryllium, the alkaline earths, magnesium, and phosphate. For the gravimetric determination a 2 per cent or 5 per cent solution of oxine in 2M acetic add may be used 1 mL of the latter solution is suffident to predpitate 3 mg of aluminium. For practice in this determination, use about 0.40 g, accurately weighed, of aluminium ammonium sulphate. Dissolve it in 100 mL of water, heat to 70-80 °C, add the appropriate volume of the oxine reagent, and (if a precipitate has not already formed) slowly introduce 2M ammonium acetate solution until a precipitate just appears, heat to boiling, and then add 25 mL of 2M ammonium acetate solution dropwise and with constant stirring (to ensure complete predpitation). 

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