Colloidal sulphur

Occurrence, Extraction, Refining, Applications—The Allotropy of Sulphur Changes in tho Vaporous State, Allotropy in tho Liquid. State, Allotropy in the Solid Stato, Crystalline Forms of Sulphur, Amorphous Sulphur— Colloidal Sulphur—General Physical Properties of Sulphur—Chemical Propertius—Valency—Atomic Weight—Detection and Estimation. 

A coarse sulphur sol can be prepared by pouring a saturated solution of sulphur in alcohol or acetone into water just below boiling point. The alcohol or acetone vaporises, leaving the water-insoluble sulphur colloidally dispersed. This technique is convenient for dispersing wax-like material in an aqueous medium. 

Following the administration of 100-200 MBq Tc-sulphur colloid intravenously, liver cirrhosis is characterized by a reduction in the uptake of radioactivity in the liver and an increased uptake by the spleen and bone marrow. Colloidal uptake in the liver is thus a valuable parameter for assessing any functional loss of the hepatic RES and for evaluating the residual parenchyma which is still functioning. It should be noted that the phagocytic capacity of the hepatic RES is closely related to the sinusoidal blood flow, the reduction of which is a result of the development of collaterals in the area of the hepatic... 

Powell-Jackson, PB., Karanl, J., Ede, R., Mire, H., Williams, R. Ultrasonic scanning and 99m Tc sulphur colloid scintigraphy in diagnosis of Budd-Chiari syndrome. Gut 1986 27 1502-1506... 

The radionuclide milk scan is a sensitive test for diagnosing GER (Blumhagen et al. 1980 Seibert et al. 1983). Milk, formula or juice mixed with Tc 99m sulphur colloid is administered to the child who is then scanned. Radionuclide scanning is continuous, an advantage over fluoroscopy. Radionuclide scanning allows documentation of episodes of GER, and... 

Oral administration to rats of DDT in solution in three oils of different chemical composition was found to yield significantly different plasma-concentration time curves (see Table 8.9). Emulsification of the oils with 6 % v/v Tween 80 had different effects on both the rate and extent of absorption and was dependent upon the nature of the oil. The effect of each oil on the total gut transit time of a co-administered "Tc-sulphur colloid was investigated. The time taken for 50 % of the marker to be excreted was determined from faecal recoveries and whole body gamma scintigraphy. The sulphur colloid was most rapidly cleared in the presence of liquid paraffin (r5o . = 9.8 3.6h). There was no significant difference in the total transit times in the presence of Miglyol 812 ( 50% = 15.5 2.0h) and arachis oil (tso% = 14.1 1.1 h). Therefore, the differences in DDT absorption may only be explained in part by the effect of oils on total gut transit time. 

Colloidal sulphur is produced by careful addition of acid to sodium thiosulphate solution. 

Chemical reduction is used extensively nowadays for the deposition of nickel or copper as the first stage in the electroplating of plastics. The most widely used plastic as a basis for electroplating is acrylonitrile-butadiene-styrene co-polymer (ABS). Immersion of the plastic in a chromic acid-sulphuric acid mixture causes the butadiene particles to be attacked and oxidised, whilst making the material hydrophilic at the same time. The activation process which follows is necessary to enable the subsequent electroless nickel or copper to be deposited, since this will only take place in the presence of certain catalytic metals (especially silver and palladium), which are adsorbed on to the surface of the plastic. The adsorbed metallic film is produced by a prior immersion in a stannous chloride solution, which reduces the palladium or silver ions to the metallic state. The solutions mostly employed are acid palladium chloride or ammoniacal silver nitrate. The etched plastic can also be immersed first in acidified palladium chloride and then in an alkylamine borane, which likewise form metallic palladium catalytic nuclei. Colloidal copper catalysts are of some interest, as they are cheaper and are also claimed to promote better coverage of electroless copper. 

It is possible that colloidal photochemistry will provide a new approach to prebiotic syntheses. The work described previously on redox reactions at colloidal ZnS semiconductor particles has been carried on successfully by S. T. Martin and co-workers, who studied reduction of CO2 to formate under UV irradiation in the aqueous phase. ZnS acts as a photocatalyst in the presence of a sulphur hole scavenger oxidation of formate to CO2 occurs in the absence of a hole scavenger. The quantum efficiency for the formate synthesis is 10% at pH 6.3 acetate and propionate were also formed. The authors assume that the primeval ocean contained semiconducting particles, at the surface of which photochemical syntheses could take place (Zhang et al 2007). 

For trace analysis in fluids, some Raman sensors (try to) make use of the SERS effect to increase their sensitivity. While the basic sensor layout for SERS sensors is similar to non-enhanced Raman sensors, somehow the metal particles have to be added. Other than in the laboratory, where the necessary metal particles can be added as colloidal solution to the sample, for sensor applications the particles must be suitably immobilised. In most cases, this is achieved by depositing the metal particles onto the surfaces of the excitation waveguide or the interface window and covering them with a suitable protection layer. The additional layer is required as otherwise washout effects or chemical reactions between e.g. sulphur-compounds and the particles reduce the enhancement effect. Alternatively, it is also possible to disperse the metal particles in the layer material before coating and apply them in one step with the coating. Suitable protection or matrix materials for SERS substrates could be e.g. sol-gel layers or polymer coatings. In either... 

Organic compounds, sulphur-, phosphorous- and nitrogen-compounds may be present as soluble, suspended or colloidal particles. This also holds for salts, bases and heavy metals. Pretreatment can change the physical state of pollutants in the wastewater. This gives a possibility for guiding the treatment process. 

To increase the solubility of calcium carbonate and reduce its potential for precipitation and hence membrane fouling, the pH of the feed water is lowered through the addition of acid (Greenlee et al. 2009). Sulphuric acid and hydrochloric acid are most commonly used. Acid treatment can also help to improve the coagulation of colloids and slightly increase the solubility of silica (Bergman 2007). 

Od6n Nova Acta Reg, Soc. Upsala, m. 4,1913) showed that the maximum adsorption of sodium chloride by sulphur particles 1000 A. in diameter yielded a value of 2 79 gms. NaCl for 100 gms. of the sulphur. If the density of colloidal sulphur be taken as A = 2 we find that one sulphur particle of area 8 x 10 sq. cm. adsorbs 3x10 molecules giving on the assumption of an unimolecular layer a mean area for the sulphur molecule of 10 sq. cm. or 10 A. which is a close approximation to the. value calculated in other ways. 

Preparation of a Sulphur Sol. Prepare a saturated solution of sulphur in ethanol in a test tube. Take 2-3 g of sulphur and 10 ml of ethanol for this purpose. The solution will become saturated after vigorous shaking during 15 min. Filter off the undissolved sulphur, measure off 5 ml of the solution, and carefully pour it dropwise into 20 ml of distilled water. Pour part of the colloidal solution into two test tubes in equal portions. Add 1 ml of water to the first tube and 1 ml of a barium chloride solution to the second one, and heat both tubes. What happens How does the electrolyte affect the stability of the solution Define a gel and a sol. 

Put a chemical beaker with a water-ethanol solution of sulphur onto shelf 4. Switch on the lamp. Shut the door of the box and through an opening in it observe the luminous cone in the colloidal solution. Re-... 

The catalyst used is colloidal nickel sulphide. The sulphur is run off from the surface, and after filtering and washing is obtained as a paste containing 55 per cent, of water. After drying, a product is obtained which is more toxic than most other forms of sulphur and is very effective in agricultural work as a fungicide the particles are almost of colloidal size, most being less than 15 p..1... 

Colloidal sulphur, sometimes designated -sulphur, consists of sulphur in such small particles that these can remain suspended in water as a colloidal solution. Such a suspension is readily formed by rapidly pouring an alcohol solution of sulphur into water,1 or similarly treating a solution of sulphur in hydrazine hydrate.2 Cathodic pulverisation, as applied commonly to the production of colloidal solutions of metallic substances, has also been successfully extended to sulphur.3... 

On account of the tendency of the suspended particles to eoalesec, colloidal solutions of sulphur are generally short-lived. The stability of the solutions can be increased by the addition of a protective colloid such as albumen or gelatine. The action of hydrochloric acid on sodium thiosulphate solution yields a colloidal solution which is more stable if the reagents are used in a concentrated condition,0 but the life of the unstable colloidal solution obtained with dilute reagents can be extended by the addition of gelatine. Also, by preparing tire sulphur in a wet way in the presence ol albumen, the... 

A sulphur sol containing sulphuric acid and sodium sulphate, which act as stabilisers, has an eleetrieal conductivity lower than that of a similar solution containing no colloidal sulphur tire freezing-point is... 

The transformation of maleic acid to fumaric acid is accelerated by the presence of colloidal sulphur.2... 

The absorption of ultra-violet light by colloidal solutions of sulphur has been examined,6 and is found to vary with the size of the colloid particle, approaching a limit corresponding with the amount absorbed by a molecular solution of sulphur in alcohol. 

Aqueous solutions of alkali chromates yield with hydrogen sulphide a precipitate of chromium hydroxide contaminated with sulphur, whilst alkali sulphide, polysulphide, thiosulphate and colloidal sulphur remain in the solution.3... 

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