Starch xanthates

Treatment of the xanthate with such compounds as benzene diazonium chloride is said to replace the sodium with phenyl to produce an entirefy organic dithiocarbonate.  

Starch xanthates have been suggested for use as adhesives for wood veneers, and as textile sizes.  

Large scale industrial development of cellulose esters of organic acids has taken place during the past twenty years. At the beginning of the World War in 1914 cellulose acetate was in the early stages of commercial manufacture. Its use for aircraft fabrics at that time brought about 

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Starch derivatives are also used to encapsulate pesticides (qv) in a cross-linked starch—xanthate to improve safety in handling and reduce water leaching losses (51,52). Littie or no pesticide is lost during drying. The encapsulated formulations have excellent shelf life when dry, but when placed in water or soil the pesticide is readily released. 

Cellulose. Cellulose or starch xanthate cross-linked by titanates can adsorb uranium from seawater (536). CarboxymethylceUulose cross-linked with TYZOR ISTT is the bonding agent for clay, talc, wax, and pigments to make colored pencil leads of unusual strength (537). 

In addition to these three treatments, there are several alternative treatment technologies applicable to the treatment of common metals wastes. These technologies include electrolytic recovery, electrodialysis, reverse osmosis, peat adsorption, insoluble starch xanthate treatment, sulfide precipitation, flotation, and membrane filtration.1516... 

Insoluble starch xanthate (ISX) releases magnesium and takes up heavy metals. There are also a number of proprietary chemicals developed by various companies (e.g. Environmental Technology of Sanford, Florida) for removal of complexed copper, silver (from photographic process wastes), arsenic, nickel, lead, mercury, zinc, cadmium, barium, and other heavy metals. 

Metal-Organics. Many organic materials also form low-solubility species with certain metals. Among these are humic acids. The most widely publicized insoluble substrate for heavy-metal immobilization has been insoluble starch xanthate (ISX). In contact with metal ions, the metal links to the sulfur group much as it would with the S-2 in inorganic sulfides ... 

Suggested industrial uses of carbohydrate xanthates, apart from the cellulose Viscose process, include the flotation of minerals and the production of plastics. Two patents by Brown and his associate claim an effective purification of both iron ore and silvinite ore by froth-flotation processes employing, for example, sodium starch xanthate, pine oil, and a suitable amine. Silberstein obtained plastic masses from mixtures of sodium dextrin xanthate with urea, formaldehyde, or glyceritol. Starch xanthate has been suggested as a dispersing, wetting, and adhesive ma-... 

It is remarkable that neither of these workers appears to have investigated aqueous preparative methods, despite the fact that Cross and Bevan and their colleagues, from 1892 onward, had been developing the Viscose process for cellulose, and had, in 1907, applied similar reaction-conditions to starch. The formation of a starch viscose imder aqueous conditions was confirmed later by Ost and coworkers, who found that the solution decreased in viscosity on storage ( ripened ), like cellulose Viscose, but with no accompanying separation of starch. Various industrial uses for starch xanthate have since been suggested for example, as a frothing... 

In the third paper of the series, concerned with the formation of -(copper thiolthiocarbonyl) derivatives of polysaccharides, Lieser and Hackl reviewed the few earlier studies on polysaccharides other than cellulose. They claimed that the starch xanthates obtained by Cross, Sevan, and Briggs and by Ost and his colleagues had been given incorrect formulas,... 

Starch xanthate. A water-insoluble synthetic polysaccharide made by reacting starch with sodium hydroxide and carbon disulfide biodegradable. 

Starch xanthide. Starch xanthate that has been cross-linked with oxygen. 

To address this concern, several organic and inorganic reagents were evaluated as precipitants for heavy metals in a 10-34-0 (N-P2O5-K2O) fluid fertilizer and WPA. Trisodium trithiocyanuric acid (TMT-15), sodium polythiocarbonate (Thio-Red II), and sodium trithiocarbonate (5% Na2 CS3) precipitated arsenic, cadmium, copper, mercury, lead, and zinc from 10-34-0. Ammonium cyanurate was ineffective in removing cadmium from 10-34-0. Thio-Red II and 5% Na2CS3 precipitated mercury, lead, cadmium, copper, and chromium from WPA. A water-insoluble starch xanthate adsorbed mercury, copper, and lead from 10-34-0 and WPA. Sodium sulfide, sodium polysulfide, and potassium ferrocyanide were tested as inorganic precipitants. The polysulfide was twice as effective as the sulfide alone, and concentrations of less than 10 ppm of arsenic, cadmium, mercury, and lead were achieved in 10-34-0. Ferrocyanide reduced the concentrations of cadmium and nickel to less than 10 ppm in WPA. 

Starch Xanthate Adsorbents. Wing and coworkers (12) reported that insoluble starch xanthate was highly effective in adsorbing iron(II) and chromium(III) from synthetic waste water samples. For example, a pH 3.0 waste water with an initial iron(II) concentration of 27,920 mg/L was treated with the starch xanthate and after stirring for 2 h, the residual iron(II) concentration was found to be <1 mg/L. Similar results were obtained for chromium(III), where the chromium(III) concentration of a synthetic waste water sample at pH 3.2 was reduced from 26,000 mg/L to 3 mg/L after stirring for 2 h with the appropriate amount of starch xanthate. 

The analytical results from the precipitation and adsorption tests conducted with TMT-15, Thio-Red n, 5% Na2CS3, and the WI starch xanthate on samples of 10-34-0 containing additional arsenic, cadmium, copper, lead, manganese, and mercury are summarized in Table II. 

WI Starch Xanthate. Research by Wing and others (22, 27-29) has shown that water-soluble (WS) starch xanthates, in combination with cationic polymers to form polyelectrolyte complexes, can effectively remove heavy metals from waste water. To eliminate the expensive cationic polymer and give a more economical method of heavy metal removal, further research by Wing and others (12,30-33) showed that xanthation of a highly crosslinked starch yields a water-insoluble (WI) product that is effective in removing heavy metals from waste water without the need for a cationic polymer. In more recent work, Tare and Chaudhari (34) evaluated the effectiveness of the starch xanthate (WS and WI) process for removal of hexavalent chromium from synthetic waste waters. 

Mercury, copper, lead, and cadmium can be precipitated from 10-34-0 by adding TMT-15. The TMT-15 and Thio-Red II precipitated at least 94% of the copper and mercury present in the 10-34-0 manganese and chromium were not precipitated. The WI starch xanthate adsorbed mercury, copper, and lead from 10-34-0, while the adsorption of arsenic, cadmium, chromium, manganese, and zinc was negligible. 

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