Potassium persulphate

Since poly(vinyl acetate) is usually used in an emulsion form, the emulsion polymerisation process is commonly used. In a typical system, approximately equal quantities of vinyl acetate and water are stirred together in the presence of a suitable colloid-emulsifier system, such as poly(vinyl alcohol) and sodium lauryl sulphate, and a water-soluble initiator such as potassium persulphate. 

To produce the Type 2 polymers, styrene and acrylonitrile are added to polybutadiene latex and the mixture warmed to about 50°C to allow absorption of the monomers. A water-soluble initiator such as potassium persulphate is then added to polymerise the styrene and acrylonitrile. The resultant materials will be a mixture of polybutadiene, polybutadiene grafted with acrylonitrile and styrene, and styrene-acrylonitrile copolymer. The presence of graft polymer is essential since straightforwsird mixtures of polybutadiene and styrene-acrylonitrile copolymers are weak. In addition to emulsion processes such as those described above, mass and mass/suspension processes are also of importance. 

Weigh out accurately about 0.3 g potassium persulphate into a conical flask and dissolve it in 50 mL of water. Add 5mL syrupy phosphoric)V) acid or 2.5 mL 35-40 per cent hydrofluoric acid (CARE ), 10 mL 2.5M sulphuric acid, and 50.0 mL of the ca 0.1 M iron(II) solution. After 5 minutes, titrate the excess of Fe2+ ion with standard 0.02 M potassium permanganate. 

Weigh out accurately 0.3-0.4 g potassium persulphate into a 500 mL conical flask, add 50 mL of 0.05 M-oxalic acid, followed by 0.2 g of silver sulphate dissolved in 20 mL of 10 per cent sulphuric acid. Heat the mixture in a water bath until no more carbon dioxide is evolved (15-20 minutes), dilute the solution to about 100 mL with water at about 40 °C, and titrate the excess of oxalic acid with standard 0.02 M potassium permanganate. 

Procedure. Weigh out accurately an amount of the salt which will contain about 0.25 g of chromium, and dissolve it in 50 mL distilled water. Add 20 mL of ca 0.1 M silver nitrate solution, followed by 50 mL of a 10 per cent solution of ammonium or potassium persulphate. Boil the liquid gently for 20 minutes. Cool, and dilute to 250 mL in a graduated flask. Remove 50 mL of the solution with a pipette, add 50 mL of a 0.1 M ammonium iron(II) sulphate solution (Section 10.97, Procedure A), 200 mL of 1M sulphuric acid, and 0.5 mL of /V-phenylanthranilic acid indicator. Titrate the excess of the iron(II) salt with standard 0.02M potassium dichromate until the colour changes from green to violet-red. 

Pipette a 25 mL or 50 mL aliquot of the clear sample solution into a 250 mL conical flask, add 5 mL concentrated sulphuric acid, 5 mL 85 per cent phosphoric(V) acid, and 1-2 mL of 0.1 M silver nitrate solution, and dilute to about 80 mL. Add 5 g potassium persulphate, swirl the contents of the flask until most of the salt has dissolved, and heat to boiling. Keep at the boiling point for 5-7 minutes. Cool slightly, and add 0.5 g pure potassium periodate. Again heat to boiling and maintain at the boiling point for about 5 minutes. Cool, transfer to a lOOmL graduated flask, and measure the absorbances at 440 nm and 545 nm in 1 cm cells. 

Peroxomonosulphate and peroxodisulphate have also been used to oxidize sulphoxides to sulphones in good yields at room temperature. Potassium persulphate (KHS05) readily oxidizes a range of sulphoxides to sulphones at 0°C in yields greater than 90%, in the presence of hydroxy, keto and alkene groups82-84. The mechanism is similar to that observed for other peroxy species, as discussed above. Peroxomonosulphate oxidation has been used as an analytical procedure for the estimation of dimethyl sulphoxide84. 

Grafting of polyacrylamide onto guar gum [431] and Ipomoea gum [178] in aqueous medium initiated by the potassium persulphate/ascorbic acid redox system was performed in the presence of atmospheric oxygen and Ag" " ions. After grafting, a tremendous increase of the viscosity of both gum solutions was achieved, and the grafted gums were found to be thermally more stable. 

Liegeois (71), using 400.0 ml of water, 280.0 gr of VCM, 280.0 mgr of potassium persulphate initiator and 2.5 gr of sodium lauryl sulphate emulsifier at 50°C, measured by electron microscopy PVC latex particle diameters close to 190 A for a conversion level of 24%. The model predicted an average particle diameter equal to 200 A for the same conversion level and for the same experimental conditions. 

A polyacrylamide with a molecular mass of 1.87 x 105 was prepared by polymerising a 5% w/v aqueous solution of acrylamide monomer in the presence of 0.15% w/w benzyl alcohol and 0.025% w/w potassium persulphate for 45 minutes at 80 °C. This product was effective in preventing the bleeding of direct dyes and hydrolysed reactive dyes from dyed cotton, which was simply dipped in a 1% solution of the polyacrylamide and dried in air [450]. 

Starting natural graphite from Zavalie deposit in, Ukraine was chemically intercalated in sulfuric acid. Potassium persulphate was used as an oxidizer. Thermal expansion of graphite was performed at 900°C [3], Carbon content in the experimental samples was of about 99.0%. 

A3 AIBN c Cp DLS DLVO DSC EO GMA HS-DSC KPS LCST Osmotic third virial coefficient 2,2 -Azobis(isobutyronitrile) Polymer concentration Partial heat capacity Dynamic light scattering Derjaguin-Landau-Verwey-Overbeek Differential scanning calorimetry Ethylene oxide Glycidylmethacrylate High-sensitivity differential scanning calorimetry Potassium persulphate Lower critical solution temperature... 

VCL N-vinylcaprolactam, SDS sodium dodecyl sulphate, MACUE042 polyethylene oxide)42 undecyl a-methacrylate, KPS potassium persulphate, VA-086 2,2 -azobis [ 2-methyl-N-(2-hydroxye thyl) propionamide ]... 

Organogermanium compounds can be mineralized by wet oxidative digestion for 4 h at 70°C, in aqueous potassium persulphate, at pH 12. After dilution to an adequate concentration germanium can be determined by ICP-AES (inductively coupled plasma atomic emission spectrometry)9. 

Hulsmann and Hengst [41] used wet oxidation by potassium persulphate in sealed ampoules to estimate particulate organic carbon. Inorganic carbon was first removed from the sample prior to reaction with persulphate. 

Potassium persulphate [53], hydrogen peroxide [51], and peroxydisulphate in alkaline medium [59], have all been used to digest river sediments prior to the determination of total nitrogen. Muhlhauser et al. [51] digested lOmg... 

Aspila et al. [60] have described a semi-automated method for the determination of inorganic, organic and total phosphorus in river and lake sediments. Total phosphorus is extracted from sediments with 1M hydrochloric acid after ignition at a high temperature (550°C) (method 1) or by digestion with sulphuric acid-potassium persulphate at 135°C in a sealed PTFE-lined Parr bomb (method 2). 

An alternate extraction procedure used by Aspila et al. [60] involves ignition of the sediment with potassium persulphate in a PTFE-lined Parr bomb. 

For the extraction of total phosphate a weighed aliquot of sediment (0.3-0.5g), together with 3 0.1g of potassium persulphate (Analar) and 5.00ml of concentrated sulphuric acid, was added to the bomb, which was then heated in an oven at 135 5°C for 2h. The contents of the bomb were then transferred quantitatively into a 500ml calibrated flask. After dilution to volume with distilled water, the extract (containing 1% v/v of sulphuric acid) was analysed for total phosphate by the automated procedure outlined below. 

Earlier work on the determination of total mercury in river sediments also include that of Iskander et al. [41], Iskander applied flameless atomic absorption to a sulphuric acid nitric acid digest of the sample following reduction with potassium permanganate, potassium persulphate and stannous chloride. A detection limit of one part in 109 is claimed for this somewhat laborious method. 

Jurka and Carter [50] have described an automated determination of down to O.lpg L 1 mercury in river sediment samples. This method is based on the automated procedure of El-Awady [51] for the determination of total mercury in waters and waste waters in which potassium persulphate and sulphuric acid were used to digest samples for analysis by the cold vapour technique. These workers proved that the use of potassium permanganate as an additional oxidizing agent was unnecessary. 

Experiment.1—Powdered potassium persulphate (18 g.) is thoroughly ground in a mortar, well cooled in ice, with 15 c.c. of concentrated sulphuric acid. The mixture, after standing for one hour, is poured on to 100 g. of ice and while being cooled is neutralised with crystalline sodium carbonate. Into this neutral solution 100 c.c. of aniline water (2-8 g. of aniline in 100 c.c. of water) are poured. After a short time nitrosobenzene separates in yellow... 

Epoxidation of alkenes can be effected by potassium persulphate. When the oxidation is conducted in the presence of chiral trifluoroketones, chiral oxiranes (ee 12-22%) are produced [14]. The chirality appears to be achieved via the initial reaction of the persulphate with the ketone to generate chiral dioxiranes, which then interact with the alkenes. 

Water-insoluble carboxylic acids are oxidized in high yield to corresponding peracids by potassium persulphate in the presence of a phase-transfer catalyst. The overall yields are ca. 25-30% higher than those obtained in the absence of the catalyst. [15]. 

For the thermally initiated (potassium persulphate) emulsion polymerisation of styrene, we have observed [73] a twofold increase in the initial polymerisation rate in the presence of ultrasound (20 kHz), the increase being dependent upon the level of surfactant employed. Several workers have suggested that possible explanations for the observed increase in rate are ... 

Fig. 5.35. Emulsion polymerisation in the presence and absence of inhibitor and in the presence and absence of ultrasound (Conditions 8% styrene (w/v), 0.8% surfactant (w/v), potassium persulphate, T= 70°C).

The second reason for acid-digestion is the determination of the total soil elemental content of, e.g. potassium, phosphorus or trace elements. This is seldom done for potassium in normal soil samples, mainly because the total K in soils is of no value as an index to the availability of K to plants, nor is it always of value in tracing the movement or accumulation of applied fertilizer K (Pratt, 1965). The unreactive soil phosphorus is obtained by subtracting the naturally leached reactive phosphorus from the total phosphorus, and a method for determining the latter by extraction with sulphuric acid and potassium persulphate is cited by Turner and FHaygarth (2000). They analysed... 

As published by Ferguson and Shah and independently by Bamford and Shiiki, polyethylene imine can be used as template for polymerization of acrylic acid. It was found that polyethylene imine forms water insoluble complex with polyacrylic acid. Polymerization was carried out at 31 C, using potassium persulphate as an initiator. The polymerization was followed by turbimetry and bromometric titration. During polymerization, the precipitation takes place, however, at GO C, degradation of the com-... 

Ferguson and Shah described polymerization of AA in the presence of polyCethylene oxide), PEG, having mol. weight of 1,500 and 6,000. Polymerizations were carried out in water at 55 and 74°C. Potassium persulphate was used as an initiator. Having examined the influence of template concentration on the rate of polymerization, it was found that the maximum rate appears not at equimolar ratio of monomer to template, but at much lower concentration of the template. Polymerization of AA in the presence of PEG in water at 74°C was treated by the authors as an example of the system in which the interaction between template and the monomer is rather weak. Indeed, only tern-... 

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