Sodium hypochlorite with cellulose

The stabilised nitrate may then be bleached with sodium hypochlorite, centrifuged to remove much of the water in which the polymer has been slurried and dehydrated by displacement with alcohol while under pressure in a press. It is interesting to note that in these processes approximately 35 000 gallons (160000 litres) of water are used for every ton of cellulose nitrate produced. Control of purity of the water is important in particular the iron content should be as low as 0.03 parts per million since iron can adversely affect both the colour and heat stability of the polymer. 

Figure 10.30 Functional groups formed by oxidising cotton cellulose with sodium hypochlorite over the pH range 5-10 [235]...

Bleaching. Crude wood cellulose is bleached by means of calcium or sodium hypochlorite in large tanks, bleachers , equipped with stirrers. Bleaching cellulose is of great importance for nitrocellulose manufacture, particularly in the case of nitrocellulose intended for the production of smokeless powder. It is essential that the powder should be pale in colour, as a change in the colour of the powder often indicates decomposition. Similarly, cellulose destined for manufacturing collodion cotton, for varnishes, celluloid and film, should be carefully stripped of colour so that the final products are colourless. 

The action of chlorine in alkaline media is much slower than that of bromine. Lewin29 reported that the rate of oxidation of D-glucose at pH 9.8 by hypobromite is 1360 times higher than that by hypochlorite at the same pH. For cellulose, the ratio is much smaller (33 to 1). The complexity of the latter system is, however, revealed by the variability of this ratio over the pH range of 8-13 at pH 6-7, the action of hypochlorite is actually slightly faster than that of hypobromite. Maltodextrins and starch have been oxidized with alkaline sodium hypochlorite. The resulting oxidized polysaccharide formed stable complexes with calcium cations.30... 

Cellulose. Reacts violently with sodium hypochlorite.7... 

Wool and silk fibres can also be dissolved out by treating with sodium hypochlorite solution for 20 min at room temperature (35 g T active chlorine and 5 g 1 caustic soda), followed by rinsing, anti-chlorine treatment with natrium thiosulphate solution and further rinsing. Cellulose, nylon, polyester, acrylic or polyvinylchloride fibres remain as residue. 

AVICEL (9004-34-6) (C HioO,), Combustible solid. Fine dust can form explosive mixture with air (flash point 770°F/410°C Fire Rating 1). Violent reaction with strong oxidizers including bromine pentafluoride fluorine, hydrogen peroxide perchlorates, perchloric acid peroxides sodium hypochlorite sodium nitrate sodium nitrite zinc permanganate. On small fires, use HjO, foam, dry chemical, or CO2 extinguishers. Nitration with a mixture of nitric and sulfuric acids produces cellulose nitrates (celluloid pyroxylin, soluble pyroxyline, gimcotton) which are flammable or explosive. 

CHLORAMBEN (133-90-4) CtHSCIjNOj Rapidly decomposed by light. Violent reaction with strong oxidizers sodium hypochlorite nitric acid cellulose nitrate (of high surface area) l-chloro-2,3-epoxypropane (exothermic). May form heat-sensitive explosive materials with digold ketenide. Incoir atible with acids, acid... 

CELLULOSE or a-CELLULOSE or CELLULOSE 248 (9004-34-6) Reacts with bromine pentafluoride, hydrogen peroxide, sodium hypochlorite, sodium nitrate, fluorine, or strong oxidizers. 

Commercially, most cellulose is extracted from wood by one of two methods, the kraft (sulfate) process or the steam explosion process. The product of these reactions is wood pulp, which consists primarily of cellulose. In the kraft process, wood chips are treated with a solution of sodium hydroxide (NaOH) and sodium sulfide (Na2S) at temperatures of about 175°C (35o°F) for two to six hours. This process usually results in a yield of about 40 to 45 percent wood pulp. The pulp is then treated with a bleaching agent, such as calcium or sodium hypochlorite (Ca(0Cl)2 or NaCIO) or chlorine dioxide (C102) to remove the color of lignin and other impurities. 

Complex side-reactions, including overoxidation, are likely to occur in the oxidations, and information on the mechanism of periodate oxidation and the periodate-oxidation products of starch, cellulose, xylan, and other polysaccharides have been discussed. Thus, the limit of periodate oxidation is not always that expected, and the formation of interresidue hemiacetal structures during the oxidation can cause an early halt. - It is not until these structures have been reduced that oxidation can proceed once more. Other oxidants, such as dichromate-sulfuric acid, dichromate-oxalic acid, and sodium hypochlorite (which cause more extensive reactions), have been investigated with respect to cellulose and periodate-oxidized cellulose. Further oxidation of 2,3-dialdehydocel-lulose with halogen peroxy acids gives 2,3-dicarboxycellulose. ... 

Precaution Highly flamm. dangerous fire hazard exposed to heat, flame, oxidizers explodes on contact with dicyanofurazan violent reaction with sulfuric acid ignites on contact with cellulose nitrate absorbs CO from air to form the carbamate salt vapor may form explosive mixts. with air sudden reaction and fire may occur if mixed with an oxidizing agent incompat. with acids, oxidizers, sodium or calcium hypochlorite may form nitrosamines with nitrous acid, nitrites, etc. 

Cellulose is nitrated by mixtures of nitric and sulfuric acids. The type of acid mixture used depends on the intended products. For the preparation of plastic grade materials, 25% nitric acid is combined with 55% sulfuric acid and 20% water. The dried cellulose is soaked for 20-60 minutes at 30-40 C. There is little change in appearance as the structure of the cellulose is maintained. The bulk of the acid is then removed, usually by spinning in a centrifuge, and the remaining acid washed out with copious amounts of water. The product is often bleached with sodium hypochlorite and washed. 

Chemical treatments, such as alkalization, bleaching with sodium hypochlorite (NaClO) or chlorite (NaCl02), are applied on the fiber bxmdles to extract the technical fiber that can stand the loads of tension and torsion. Chemical treatments are effective in removing the extra celulosic materials and exposing the cellulose. However, if the alkalization conditions are too strong, this may cause damage in the fiber [15]. 

The process operated by ACI is outlined in Figure 7. Bales of cotton linter are opened, cooked in dilute caustic soda, and bleached with sodium hypochlorite. The resulting highly purified cellulose is mixed with pre-precipitated basic copper sulfate in the dissolver, and 24-28% ammonium hydroxide cooled to below 20°C is added. The mixture is agitated until dissolution is complete. If necessary, air is introduced to allow oxidative depolymerization and hence a lowering of the dope viscosity. 

A process to remove polyester and cellulose contamination from PP bale wrapper for cotton and polyester fibers involves treating the PP with aqueous sodium hydroxide solution followed by an oxidizing agent such as aqueous sodium hypochlorite. ... 

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