Hydrogen peroxide method

In the department of Prof. Nienow, Birmingham University, an interesting method has been developed [356], which utilizes the catalytic decomposition of hydrogen peroxide and works on the assumption that for G/L mass transfer it is unimportant whether its direction is L — G or G — I. The decomposition of hydrogen peroxide according to the equation  

As in the hydrazine method, hydrogen peroxide is fed in continuously. In the steady-state cq = const and thus the oxygen formation rate is the same as its desorption rate from the liquid in the gas phase. 

Most of the measurements concerning mass transfer in G/L system were carried out with the turbine stirrer, because very early it became apparent, that stirrers with resistance due to their shape are the most suitable for dispersing gas. There are indeed measurements, which prove that turbine stirrers with 12 paddles are energetically more favorable than those with 6 paddles [248], In several publications differently designed hollow stirrers have been utilized. Hollow stirrers are also excellent gas dispersers in addition to their sucking the gas in. 

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Diatoms and the Scanning Electron Microscope Acid Treatment Method Hydrogen Peroxide Method Obtaining Diatom Specimens from Sediments Preparation of Attached Diatoms Preparing Cleaned Diatoms for Viewing on the Scanning Electron Microscope References... 

Fig. 2. Scanning electron micrographs of diatoms prepared using the hydrogen peroxide method. (A) A naviculoid diatom (bar = 10 pm). (B) Fragilaria sp. (bar= 13 pm).

A series of compds which contain both acetylene bonds and peroxide groups, was synthesized by Milas et al by using a modification of the sulfuric acid-hydrogen peroxide method originally described in Refs 1 ... 

Gaseous Hydrogen Peroxide. Methods for determination of gas-phase hydrogen peroxide have been reviewed (79-81). Hydrogen peroxide is determined by either scrubbing air with an aqueous solution and measuring the resultant liquid-phase peroxide or by measuring the peroxide directly with a spectroscopic technique. The method that has been most commonly... 

Soya bean Catalytic hydrogen peroxide Methods devised in the 1940s... 

Table V.24 Separation of Group IIIB cations with the hydrochloric acid-hydrogen peroxide method The ppt. may contain CoS, NiS, MnS, and ZnS. Wash well with lper cent NH4C1 solution to which 1 per cent by volume of (NH4)2S has been added reject the washings. Transfer the ppt. to a small beaker. Add 5 ml water and 5 ml 2m HC1, stir well, allow to stand for 2-3 minutes and filter (1).

Table V.25 Separation of Group IIIB cations with the hydrochloric acid-potassium chlorate-hydrogen peroxide method The ppt. may contain CoS, NiS, MnS, and ZnS. Wash well with 1 per cent NH4C1 solution to which 1 per cent by volume of yellow ammonium sulphide solution has been added reject the washings. Transfer the ppt. to a porcelain basin, add 5 ml water and 5 ml concentrated HC1 and stir for 2-3 minutes. If a black residue is obtained, the presence of NiS and CoS is indicated if complete dissolution takes place, only small amounts of Ni and Co are likely to be present. Evaporate the mixture to 2-3 ml in the FUME CUPBOARD, add 4 ml concentrated HN03 (1) and concentrate to 2-3 ml. If the solution is not clear, dilute with 8-10 ml water, filter off the sulphur and return the filtrate to the porcelain basin in the fume cupboard. Boil down to 1-2 ml, taking great care not to evaporate to dryness. Add 5 ml concentrated HN03 and evaporate again to 1-2 ml (2).

VI.14 SEPARATION AND IDENTIFICATION OF GROUP IIIB CATIONS ON THE SEMIMICRO SCALE The separation scheme outlined in Table VI. 16 commences with the sulphide precipitates obtained according to the prescriptions of the general separation table (Table VI. 11 in Section VI.9). It is a semimicro adaptation of the hydrochloric acid-hydrogen peroxide method, described in Table V.24 (Section V.15). 

At higher concentrations titanium is determined by the hydrogen peroxide method. Higher sensitivities are attained with the methods using chromotropic acid. The thiocyanate (with extraction) and fluorone methods are the most sensitive. 

Titanium has been determined in the presence of V and Mo by derivative spectrophotometry [20]. The hydrogen peroxide method has been used in determining Ti by the FIA technique in the presence of V [21]. 

The hydrogen peroxide method has been used for determining titanium in uranium alloys [83], ilmenite ore [84], and silicon-based catalysts [85]. Titanium was determined in steel by derivative spectrophotometry [86]. 

Both the A(+)-mer and A(—)-mer tris(valinato) isomers were inverted in boiling ethanol by activated charcoal. The A(—)-mer isomer was rearranged to give a mixture containing ca. 60 % A —)-mer and 40 % A(+)-imr. The fac isomers could be obtained only by the oxidation with hydrogen peroxide (method d), the yield for each fac isomer (ca. 15 mg) was considerably less than the amount (ca. 0.5 g) for each mer isomer. On account of this poor yield, no analysis was made of the percentage compositions of the fac isomers. 

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