Solution mixing disadvantages

The total consumption type of burner consists of three concentric tubes as shown in Fig. 21.5. The sample solution is carried by a fine capillary tube A directly into the flame. The fuel gas and the oxidant gas are carried along separate tubes so that they only mix at the tip of the burner. Since all the liquid sample which is aspirated by the capillary tube reaches the flame, it would appear that this type of burner should be more efficient that the pre-mix type of burner. However, the total consumption burner gives a flame of relatively short path length, and hence such burners are predominantly used for flame emission studies. This type of burner has the advantages that (1) it is simple to manufacture, (2) it allows a totally representative sample to reach the flame, and (3) it is free from explosion hazards arising from unbumt gas mixtures. Its disadvantages are that (1) the aspiration rate varies with different solvents, and (2) there is a tendency for incrustations to form at the tip of the burner which can lead to variations in the signal recorded. 

As a further disadvantage, it is known concerning operation in many parallel micro channels that mixed flow patterns and even drying of the channels can occur [9, 10]. This comes from phase maldistribution to the channels. To overcome this problem, first solutions for phase equipartition have been proposed recently, but so far have not been applied for the mixers described here, but instead for mini-packed reactors, having feed sections similar to the mixers [11,12]. Nevertheless, numbering-up of dispersive-acting micro devices generally seems to be more complicated than for two-phase contactors (see Section 5.1.1). 

However, the former apparatus, proposed by Hara et al. [69], in which two streams comprising a buffer solution and a CL reagent solution are applied, presented some disadvantages such as a lowering of CL intensity due to the buffer solution and the difficulty of maintaining steady-state mixing. To overcome these problems, this research group developed a new, simple, and inexpensive online... 

The Osmotic pressure equilibrium in this type of osmometers is attained quick and very small quantities of solvent and solution are needed in this case. Sometimes mixed solvents may be used in this type of osmometer. The disadvantages of the osmometer Organisation and Qualities... 

Hydrometallurgical methods can be applied when low-grade oxidized (oxide) or mixed (oxidized and sulphidic) ores are available. These methods have advantages of high selectivity disadvantages are the relative slowness of leaching and the large volume of solution per unit mass of copper. 

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