Silica- cellulose film with

Thin layer chromatography is in principle similar to paper chromatography when used in the ascending method, i.e. the solvent creeps up the stationary phase by capillarity. The adsorbent (e.g. silica, alumina, cellulose) is spread on a rectangular glass plate (or solid inert plastic sheet). Some adsorbents (e.g. silica) are mixed with a setting material (e.g. CaSC>4) by the manufacturers which causes the film to set on drying. The adsorbent can... 

In biocatalytic systems, catalase is mainly used in immobilized state. High activity of immobilized catalase was achieved on its sorption immobilization on cellulose [6], on silica gel modified with fatty acids or phospholipids [7] as well as on activated carbon fibres and brics/tissues/ [8]. Biocatalytic activity of catalase immobilized on cellulose was also studied in nonaqueous solvents [9,10]. In [9] it was found that unlike the enzyme dissolved in water-dimethylformamide medium, on the oxidation of o-dianisidine in the presence of dimethylfonnamide the immobilized catalase does not show any peroxidase activity. It was used [10] for working out an organic-phase amperometric biosensor by immobilizing the enzyme in a polymeric film on a glass-carbon surface. 

A new method for preparation of silica films containing dispersed nano-particles of CuS and An is reported. These parddes were g erated flirough reaction with H2S gas with their precursors which were uniformly dissolved in silica films as promo by a compadbilizer, hydroxypropyl cellulose(HPC). All films with characterisdc colors were transparent The particle size, size distribution and composite structure of the films depended on the precursor concentration and matrix composition. Electric conductivity was observed for the CuS... 

Before and after the works described above, contributions to the design and fabrication of similar multicomponent films or gels of cholesteric character, mainly based on HPC, EC, or their derivatives were also made [202, 219-224], Some of these [219,220,224] dealt with shear-deformed network systems preserving a unique banded structure, so that the disappearance and recovery of the optical anisotropy could be controlled thermo-reversibly. Special mention should be made of the successful preparation of two novel classes of solid materials maintaining cholesteric liquid-crystalline order. One consists of essentially pure cellulose only, and the other is a ceramic silica with an imprint of cellulosic chiral mesomorphy. 

Fig. 2a, b. SEM images of a the membrane template (cellulose acetate) b the final silica film. Adapted with permission from [12], Copyright 2002 WUey-VCH... 

The thin film composite membrane exhibited superior overall rejection performance in these tests, with ammonia and nitrate rejection showing an outstanding improvement. It has also been reported that silica rejection by the thin film composite membranes is superior to that of cellulose acetate. While the above data indicates a marginal improvement in the rejection of chemical oxygen demand (COD), which is an indication of organic content, other tests conducted by membrane manufacturers show that the polyurea and polyamide membrane barrier layers exhibit an organic rejection that is clearly superior to that of cellulose acetate. Reverse osmosis element manufacturers should be contacted for rejection data on specific organic compounds. ... 

Indeed, polysaccharide-silica composites are frequently used for the formation of electrochemical films, because there is a large affinity between cellulose and the silicate oligomers in addition to the compatibility in the nature of solvents that can be used. The opposite is also true, and silicates (particularly sodium silicate) are useful additives in the paper industry. Chitosan is quite appealing, at least from the interpenetration point of view, because in addition to all these benefits, it is also positively charged and thus undergoes electrostatic interactions with the deprotonated silanols and can also assist in the attachment of biomolecules that are often negatively charged. 

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