Cellulose, complexes with iron

The major components of dietary fiber, cellulose and the hemicelluloses, form complexes with iron (2 D Dietary fiber may promote the conversion of iron II to iron III in some circumstances. Such a conversion would tend to decrease iron availability. 

Magnesium compounds retard cellulose depolymerization by deactivating the transition metal catalysts. In alkaline media where hydroxy-acids or products of polysaccharide degradation are present, magnesium forms stable complexes with transition metals. The formation of iron-magnesium complexes in particular is supported by interactions approximating the coordination number of iron (6) and one half the coordination number (3). 

The complex-formation of polysaccharides with alkali metals and alkaline-earth metals has already been discussed in this Series. A dextran-iron complex has been used in the experimental therapy of synovitis, and chondroitin sulfate-iron colloids have been prepared. The swelling of cellulose in aqueous solutions of zinc chloride depends on the formation of a complex with the vicinal 2- and 3- hydroxyl groups of the repeating unit. ... 

The non-ionic cellulose ethers do not form irreversible, insoluble, complexes with metal ions (in contrast to sodium carboxymethyl cellulose), but may be precipitated by high concentrations of salts. CMC forms a gel when reacted with divalent ions like Ca (Clasen and Kulicke, 2001). CMC will react with iron, alu-... 

It is otherwise with cotton, which is almost chemically pure cellulose, and hence is chemically indifferent in a tinctorial sense. Here combination with the dye results from the use of mordants which are adsorbed colloidally on the fibre before dyeing. The mordant can then enter into chemical union with the dye as a complex compound. For an important group of acid dyes (p. 335) the mordants are chiefly metallic hydroxides, namely, those of chromium, aluminium, iron, antimony, tin, etc., whilst for basic dyes tannin is the usual mordant. 

A successful process has been developed by the National Chemical Laboratory using cellulose phosphate as a cation-exchange material for the purification of thorium from rare earth elements. Monazite sand is broken with sulphuric acid and extracted with water to give a solution of thorium and rare earth sulphates and phosphates. This is first treated with metallic iron or aluminium to reduce the ferric iron impurity to the ferrous condition. The solution is then fed through a colunm of cellulose phosphate to absorb the thorium. Some of the thorium is present in solution as a cationic phosphate complex, rather than as simple thorium cations, but both forms are retained by the column to a high degree. Rare earth elements, which predominate in the feed solution, are not appreciably absorbed, and the ratio of thorium to rare earths is increased to about 450. ... 

Enzyme adsorption by cellulose films was observed by several methods, including XPS, and was followed by enzymic degradation of the films. Silicate glass surfaces were found to be depleted in Fe and Al as a result of exposure to Bacillus sp. XPS revealed that reduced sulfur forms in aqueous solutions of coal-derived products were not oxidized by dibenzothiophene-degrading bacteria, supporting the indication that extensive degradation of the carbon structure was concurrent with the loss of sulfur. In the context of the extraction of iron from a hornblende by Arthrobacter sp., the formation of siderophore-Fe surface complexes was examined by an XPS study of Fe with and without the siderophore on gold surfaces, and of the siderophore on hornblende crystal surfaces. ... 

Biosensitisers and photosensitisers are nsed to obtain PE with predictable life times. Iron complexes Fe(iii)-acetylacetonate, Fe(iii)-2-hydroxy-methylacetophenoneoxime, transition metal (Co, Ni, Cr, Zn)-N,N -diethyldiselenocarbamates or other metallic complexes, and blends with natural polymers (starch, cellulose, lignin, proteins) are mostly used. 

Polymerization of 4-vinylpyridine has also been performed, resulting in a non-electroactive and non-conducting coating . The kinetics of charge transport has been measured when this polymer contains electrostatically trapped Fe(CN)6 ", IrCls " or tris(2,2 -bipyridine)osmium- 111/11) complexes 3 . Incorporating IrCle , the electrode is able to catalyze the oxidation of iron(II) . A composite electrode coated with a mixture of cellulose acetate and poly(vinylpyridine) has been described . This mixture allows the binding of counterionic reactants in acidic media, while maintaining the size exclusion discriminative properties of cellulose acetate. 

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