Precipitation waters, hydrogen peroxide

Potentiometry biosensors, 664 fitness for purpose, 663 hydrogen peroxide determination, 650-1 iodine-iodide buffer, 699 measurement uncertainties, 663 peroxide value, 663-4 transition metal peroxides, 1069 POV see Peroxide value POZ see Primary ozonides Precipitation waters, hydrogen peroxide determination, 637... 

Precipitate formation can occur upon contact of iajection water ions and counterions ia formation fluids. Soflds initially preseat ia the iajectioa fluid, bacterial corrosioa products, and corrosion products from metal surfaces ia the iajectioa system can all reduce near-weUbore permeability. Injectivity may also be reduced by bacterial slime that can grow on polymer deposits left ia the wellbore and adjacent rock. Strong oxidising agents such as hydrogen peroxide, sodium perborate, and occasionally sodium hypochlorite can be used to remove these bacterial deposits (16—18). 

The action of hydrogen peroxide on freshly precipitated hydrated Ti(IV) oxide or the hydrolysis of a peroxide compound such as K2[Ti(02)(S0 2] yields, after drying, a yellow soHd, stable below 0°C, of composition TiO 2H2O. There is one peroxo group per titanium, but the precise stmcture is not known. The yellow soHd loses oxygen and water when heated and Hberates chlorine from hydrochloric acid. When freshly prepared, it is stable in acid or alkah, giving peroxy salts. 

The equihbrium is shifted by removal of the water (134) or removal of the peracid by precipitation (135,136). Peracids can also be generated by treatment of an anhydride with hydrogen peroxide to generate the peracid and a carboxyHc acid. 

Determination of sulphite by oxidation to sulphate and precipitation as barium sulphate Discussion. Sulphites may be readily converted into sulphates by boiling with excess of bromine water, sodium hypochlorite, sodium hypobromite, or ammoniacal hydrogen peroxide (equal volumes of 20-volume hydrogen peroxide and 1 1 ammonia solution). The excess of the reagent is decomposed by boiling, the solution acidified with hydrochloric acid, precipitated with barium chloride solution, and the barium sulphate collected and weighed in the usual manner (Section 11.72). 

C. 3,5-Dibromosulfanilamide. The bromination of sulfanilamide is carried out in much the same way as the chlorination. The stirrer must be more efficient (Note 9) a glass stirrer with two sets of blades is satisfactory if run at high speed. Fifty grams (0.29 mole) of sulfanilamide is dissolved in a mixture of 850 ml. of water (Note 9) and 100 ml. (0.68 mole) of 40% hydro-bromic acid (Note 10). The solution is heated as above, but to 70-75°, and 65 g. (59 ml., 0.58 mole) of 30% hydrogen peroxide is added (Notes 2 and 11). A precipitate settles in 2 to 3 minutes, and the solution becomes yellow. The heat of reaction causes the internal temperature to rise without further application of heat to a maximum of 85-90° after 10 minutes by the end of the reaction time the temperature will have fallen to about... 

A. 3,5-Dichlorosulfanilamide. In a 2-1. round-bottomed flask, fitted with a two-holed stopper carrying a mechanical stirrer and a thermometer, are placed 50 g. (0.29 mole) of sulfanilamide and 500 ml. of water. About 50 ml. of a 500-ml. portion (approximately 6 moles) of pure concentrated hydrochloric acid is added, and the mixture is stirred until a clear solution results (Note 1). The remainder of the 500 ml. of hydrochloric acid is then added. If the internal temperature does not rise to 45°, the stirred solution should be warmed gently with a free flame until this temperature is reached. At this point 65 g. (59 ml., 0.58 mole) of 30% hydrogen peroxide (sp. gr. 1.108) is added and rapid stirring is initiated (Note 2). The heat of reaction causes a progressively faster rise in temperature. After 5 minutes the solution fills with a white precipitate which increases rapidly in amount and becomes delicately colored. When the temperature has reached 60°, about 10 minutes after adding the peroxide (Note 3), any further rise is preferably prevented by judicious cooling (Note 4). The reaction is allowed to proceed for 15... 

MercOx A process for removing mercury and sulfur dioxide from flue-gases. Hydrogen peroxide is first sprayed into the gas, converting metallic mercury to mercuric ions in solution. A water spray removes the sulfur dioxide as sulfuric acid. Mercury is removed from the liquor by ion-exchange, and the sulphate is precipitated as gypsum. Developed by Uhde and Gotaverken, with the Institut fur Technische Chemie. 

The resulting red solution is quickly filtered by suction, and hydrogen peroxide is added to the filtrate until a yellow precipitate appears. Dilute hydrochloric acid is added until the mixture is acidic to litmus, and the precipitate is collected by suction filtration, washed well with water, and air-dried. Five to seven grams of anthraquinone, m.p. 280-283°, may thus be obtained. 

To a heavy-walled, 2 liter suction flask is added a suspension of 9.3 gm (0.10 mole) of aniline in 150 ml of water containing 10 ml (0.088 mole) of 30% hydrogen peroxide. The flask is placed under reduced pressure and then pressurized to 5 psi with carbonyl sulfide. A snug-fitting rubber stopper and the clamped rubber tubing were sufficient to hold the pressure for 24 hr. The solid product precipitated and was isolated to yield 9.0 gm, m.p. 231°-232°C. 

Addition of 1 1. of cold water to the acetone filtrate from which the second crop of benzil is separated causes about 5 g. of impure benzil to precipitate. This may be added to the crude benzil of a subsequent run prior to the treatment with hydrogen peroxide and alkali. 

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