Cellulose sodium carbonate concentration

The only other noticeable effect of variation of the experimental parameters shown (Table I) is a negative effect of high alkali concentration on oil yield, when the sodium carbonate concentration is raised to 2.37 N (12.6%) at 270-343 C. This is counter to Elliott and Giacoletto s results (10). The effect of alkali on cellulose chain peeling and cleavage was found to be directly proportional to alkali concentration at lower temperatures (185 C) (47). Since high alkali concentrations favor the hydride- transfer mediated Cannizzaro reaction to yield acid salts and alcohols from aldehydes and some ketones, we suggest that perhaps the lower oil yield may be due to removal of carbonyl intermediates from the reaction. 

The hydroxyl groups of the cellulose appear to be somewhat acidic. While studies of the composition of alkali cellulose and adsorption of sodium hydroxide have not clearly proved the presence of any sodium compound in alkali cellulose, the reactions of alkali cellulose with carbon disulfide and with etherifying agents would seem to justify the assumption that such an intermediate exists or that the hydroxyl hydrogen at least ionizes. This view is strengthened by the fact that the rate of etherification is proportional to a high power of the concentration of alkali.19... 

The sulphate process consists in kiering pieces of wood in a solution composed of sodium hydroxide, sodium sulphide and sodium carbonate in a 65 15 20 ratio. The concentration of the solution is 10-12% of NaOH. Boiling at a temperature of 170-175°C under pressure lasts about 6 hr, of which 3 hr are required for heating, the other 3 hr being the kiering proper. Cellulose is then separated from the lye, washed with water, bleached, and subjected to final purification. The lye is condensed, evaporated to dryness, then sodium sulphate is added, and the whole is calcined. The sodium sulphate is thus reduced to sodium sulphide. Unchanged sulphate and the excess of carbonate are removed by addition of milk of lime. 

Artificial silk (viscose rayon) is spun from a viscous medium that is produced by reacting cellulose with carbon disulfide in alkali. The unusual success of this reaction prompted scientists to analyze similar reactions with starch, and indeed, starch viscose can be obtained.2134,2135 The properties of xanthates (32), mainly the degree of substitution, depend on such reaction conditions as the proportions and concentrations of reagents, and the duration and temperature of the process. Xanthation of starch using 2-3 moles of sodium hydroxide in 5-20% aqueous solutions per mole of starch and 20-25 mL of carbon disulfide per 10 g of starch is complete within 24 h of shaking at room temperature. Further studies suggested a 3-molar NaOH solution as the most suitable.2136 The temperature is a critical parameter and... 

The experimental details of the swelling treatment are as follows 1500 ml. of acid of the required concentration were made up by weighing. The acid was cooled to 2°C. and 60 grams of air-dried cotton stirred in. After thorough mixing the cotton and acid were allowed to stand for one hour in an ice-water bath and the mixture was then poured into 10 liters of water at 2°C. The cellulose was filtered off, washed repeatedly with water, then with 1% sodium carbonate solution and finally with water until washings had the same refractive index as distilled water. The cellulose was drained free of water and stored moist at 5°C. until required. 

The elution profile of cytochrome P-448 (absorption at 418 nm) and epoxide hydratase activity from a sodium cholate-solubi-lized hepatic microsomal preparation (from DBA-treated male skates) applied to a DEAE-cellulose column and eluted with Buffer II is shown in Fig. 3. The void volume of the column contained significant amounts of epoxide hydratase activity. Fractions 40-70 (Fig. 3) were combined, and concentrated. The carbon monoxide difference spectrum, which had an absorption maximum at 448 nm in the induced state, is shown in Fig. 4. This form of the cytochrome (i.e.,... 

Geometric effects coupled with diffusion and nucleation usually control the rates of all solids deposition phenomena. Such effects can be put to good use in the production of special products such as cellulose yarn (rayon), by the precipitation of cellulose in filament form as it emerges as sodium cellulose xanthate liquid from the spinnerets into a bath containing sulphuric acid, which extracts the sodium as sodium sulphate, and the carbon disulphide. In a similar manner, the fabrication of aromatic polyimide fibres is performed by dissolving the polymer in concentrated sulphuric acid and forcing the solution through spinnerets into water. 

Uses and Physiological Properties of Carbon Disulphide.—Besides its employment as a solvent (see p. 260), carbon disulphide is used extensively in the manufacture of viscose silk. Viscose is a solution of the sodium salt of the cellulose ester of thiolthioncarbonic acid (p. 268) in water or dilute aqueous sodium hydroxide, or it may be described as an aqueous solution of the sodium salt of cellulose xanthic acid. For its production cellulose is steeped in concentrated sodium hydroxide solution and then pressed, the product being called alkali-cellulose and the formula CeH10O5.NaOH assigned to it. This is converted into viscose by treatment with carbon disulphide, when the colour changes to golden yellow ... 

Cellophane had its beginnings in 1892, when Charles Cross and Edward Beven of England found that treating cellulose with concentrated sodium hydroxide followed by carbon disulfide created a thick, syrupy, yellow liquid they called viscose. Extruding the viscose into an acidic solution generated a tough cellulose filament that could be used to make a synthetic silky cloth, today called rayon (Figure 18.10). 

A method has been reported for the determination of calcium, copper, iron, magnesium, potassium, sodium and zinc in cellulose [169]. The sample (10 g) was air-dried and then ashed at 575°C until all the carbon was removed. Hydrochloric acid (5 ml of 6M) was added to the residue and evaporated to dryness twice before taking up the sample in a third aliquot, diluting to 100 ml and aspiration into an air /acetylene flame. It is likely that volatile elements such as cadmium may be lost at such an elevated ashing temperature and temperatures below 500°C may be preferable. Alternatively wet ashing with nitric acid has been proposed for the determination of aluminium, cadmium, potassium and zinc in pressed boards [170] or sodium in gypsum glass board [171]. For the determination of lead in confection wrappers, the sample may be treated with concentrated nitric acid at 70—80°C and diluted for flame analysis [172]. In the full method, the wrapper was wiped clean with a damp tissue, cut up to 0.5 X 0.5 mm pieces and dried at 110°C (for paper, for plastic 80°C) for 1 h. The sample (0.5 g) was heated with concentrated nitric acid (1ml) at... 

Carbon disulfide is widely used in production of rayon, carbon tetrachloride, rubber chemicals and cellulose film, and is a by-product of widely used dithiocarbamate pesticides. Chronic low level and long term exposure to CS2 can cause eye, ear, cardiovascular, nervous system and reproductive effects (Tan et al., 2001), (WHO Criteria 10, 1979), (Kaloyanova, 1981). There are scientific reports that the long term exposure to low concentrations of CS2 is related to endocrine disturbances as well (Lancranian I. et al., 1972) (Lyubomirova K. et al., 2006). Carbon disulfide is mostly used in viscose industry to yield sodium cellulose xanthate from alkali cellulose. (Tan et al., 2001). 

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