Cellulose removal

Probes for pH measurement and simultaneous cellulose removal and bleaching... 

This chapter examines various probes for pH measurement such as ion-selective and glass-membrane electrodes as well as simultaneous cellulose removal and bleaching of textiles with enzymes. 

Simultaneous cellulose removal and bleaching with enzymes... 

In this chapter, a method is described to remove simultaneously cellulose and bleach fibre products in the same bath with an acidic medium. An account is also given of a sensor system for measuring and controlling the hydrogen peroxide concentration. For the first purpose, enzymes are used that catalyse the oxidation of the cellulose-structure. In this cellulose-removal process oxygen, dissolved in the process liquid, is consumed and hydrogen peroxide is formed (Equation3.7) ... 

LH Cellulose Removed damaged protein from hormone (S24)... 

However, there are some methods for extraction of cellulose from plants. Han and Rowell s (1996) method describes a procedure for extraction of holocellulose, hemicelluloses, cellulose and lignin [18]. The method consists of four principle steps (1) preparation of sample (grinding of the wood), (2) removal of extractives, (3) preparation of holocellulose (removal of lignin), (4) preparation of a-cellulose (removal of hemicellulose). Several other procedures for a-cellulose extraction from wood samples have already been described during the last decades. Older methods used benzene-methanol instead of toluene-ethanol as organic solvent for the second step. Toluene-ethanol works as well as benzene-methanol mixture, and reduces health risks associated with the use of benzene and methanol. 

Alpha-protein n. Protein obtained from Soya beans which is chiefly glycinin. The process of extraction of the protein from the beans involves dissolution of the protein and separation from cellulose, removal of carbohydrates, and hydrolysis of the protein to reduce its chemical complexity. Its uses are similar to those of casein, with which it has much in common, being employed in water paints, emulsions, and adhesives of all types. 

CH2CI2. A colourless liquid with a chloroform-like odour b.p. 4I°C. Prepared by heating chloroform with zinc, alcohol and hydrochloric acid manufactured by the direct chlorination of methane. Decomposed by water at 200°C to give methanoic and hydrochloric acids. Largely used as a solvent for polar and non-polar substances, particularly for paint removal (30%), dissolving cellulose acetate and degreasing (10%). It is more stable than carbon tetrachloride or chloroform especially towards moisture or alkali. It is somewhat toxic. U.S. production 1981 280000 tonnes. 

Cellulose Acetate, Propionate, and Butyrate. Cellulose acetate is prepared by hydrolyzing the triester to remove some of the acetyl groups the plastic-grade resin contains 38 to 40%... 

Bacterial cellulose Bacterial leaching Bacterial removal Bacteria, luminous Bactericide... 

The predominant cellulose ester fiber is cellulose acetate, a partially acetylated cellulose, also called acetate or secondary acetate. It is widely used in textiles because of its attractive economics, bright color, styling versatiUty, and other favorable aesthetic properties. However, its largest commercial appHcation is as the fibrous material in cigarette filters, where its smoke removal properties and contribution to taste make it the standard for the cigarette industry. Cellulose triacetate fiber, also known as primary cellulose acetate, is an almost completely acetylated cellulose. Although it has fiber properties that are different, and in many ways better than cellulose acetate, it is of lower commercial significance primarily because of environmental considerations in fiber preparation. 

The precipitated cellulose acetate is filtered from the dilute (25—36%) acetic acid. The acetic acid and salts remaining from the sulfuric acid neutrali2ation are removed by washing. The wet polymer is typically dried to a moisture content of 1—5%. The dilute acetic acid obtained from the washing and precipitation steps caimot be used in other stages of the process. Its efficient recovery and recycle are an economic necessity. 

Filtration of viscose is not a straightforward chemical engineering process. The solution of cellulose xanthate contains some easy-to-deal-with undissolved pulp fibers, but also some gel-like material which is retarded rather than removed by the filters. The viscose is unstable and tends to form more gel as it ages. Its flow characteristics make the material close to the walls of any vessel or pipe move more slowly, get older, and gel more than the mainstream viscose. So while filtration can hold back gels arising from incomplete mixing, new gels can form in the pipework after the filters. 

The dark blue solution containing 5—10% of cellulose with a DP of 1000—2000 is filtered through a series of plate-and-frame filter presses using fine mesh metal screens to remove any particles that might block the spinneret holes. It is then deaerated under vacuum and stored ready for spinning. Unlike viscose dope, the cuprammonium cellulose [9050-09-3] solution is relatively stable. 

A high percentage of the ammonia can be recovered from the spin-bath effluent and by washing prior to the final acid bath. During acidification, remaining ammonia is converted to the sulfate and recovered when the acid wash Hquor is treated with carbonate to recover the copper. Ammonia residuals in the large volumes of washwater can only be removed by distillation. Overall about 75—80% of the ammonia requited to dissolve the cellulose can be recovered. 

Other. 2-Nitro-1-butanol is an excellent solvent for many polyamide resins, cellulose acetate butyrate, and ethylceUulose. It can be utilized in paint removers for epoxy-based coatings. 2-Hydroxymethyl-2-nitro-l,3-propanediol is usebil for control of odors in chemical toilets. Its slow release of formaldehyde ensures prolonged action to control odor, and there is no reodorant problem which sometimes is associated with the use of free formaldehyde. 2-Hydroxymethyl-2-nitro-l,3-propanediol solutions are effective preservative and embalming fluids. The slow Uberation of formaldehyde permits thorough penetration of the tissues before hardening. 

Thickeners. Thickeners are added to remover formulas to increase the viscosity which allows the remover to cling to vertical surfaces. Natural and synthetic polymers are used as thickeners. They are generally dispersed and then caused to swell by the addition of a protic solvent or by adjusting the pH of the remover. When the polymer swells, it causes the viscosity of the mixture to increase. Viscosity is controlled by the amount of thickener added. Common thickeners used in organic removers include hydroxypropylmethylceUulose [9004-65-3], hydroxypropylceUulose [9004-64-2], hydroxyethyl cellulose, and poly(acryHc acid) [9003-01-4]. Thickeners used in aqueous removers include acryHc polymers and latex-type polymers. Some thickeners are not stable in very acidic or very basic environments, so careful selection is important. 

---