Scouring of wool

Most of the trichloroethylene produced is used for metal degreasing. Other important uses are in the scouring of wool and as an extractive solvent, e.g. for olive and soya bean oils. Minor uses are as a heat transfer medium, anaesthetic, insecticide and fumigant, paint remover and fire extinguisher. 

Scouring machines of wool depend on the kind of wool to be scoured i.e. raw wool, hank form or woven fabrics. Scouring of wool can be carried out in batch or continuous process, aqueous or solvent media and rope or open width form. 

Scouring of wool is mainly done by detergent and solvent. The main components of wool scouring waste water are wool grease, suint and dirt and excrement. Table 13.13 shows the pollutant load of the wool scouring effluent. The detergent... 

The scouring of wool differs from cotton in two essential respects. In the first place, raw wool contains anything from 30 to 60 per cent of wool grease, compared with 0-5 per cent of oil and wax in cotton. In the second place, wool is very rapidly degraded by alkali so that if the natural oils and fats are to be saponified the alkali must be applied with caution and at temperatures well below the boil. In practice, sodium hydroxide is never used because the slightest excess would raise the pH above the danger level, and milder alkalis such as sodium carbonate and ammonia or ammonium carbonate are preferred. 

Plasma technologies have been investigated for quite some time with the aim of improving wettability and thus the adhesion of coatings. However, a much broader range of applications is feasible with plasma (Buyle, 2009) these apphcations include the improvement of printability and dyeability (Rahman and Nur, 2014), and antishrink treatment of wool, the scouring of wool (Rahman and Nur, 2014), sterilization, and the desizing of cotton. 

B. O. Bateup, Wool Scouring and Worsted Carding Mew Approaches, CSIRO Division of Wool Technology Symposium, Geelong, Australia, Nov. 1986. 

Trichloroethylene is an excellent extraction solvent for greases, oils, fats, waxes, and tars and is used by the textile processing industry to scour cotton, wool, and other fabrics (lARC 1979 Kuney 1986 Verschueren 1983). The textile industry also uses trichloroethylene as a solvent in waterless dying and finishing operations (McNeill 1979). As a general solvent or as a component of solvent blends, trichloroethylene is used with adhesives, lubricants, paints, varnishes, paint strippers, pesticides, and cold metal cleaners (Hawley 1981 lARC 1979 McNeill 1979). 

Advantages claimed for this process [148] include improved whiteness, decrease in ash content, improved grease recovery and quality, optimisation of water consumption, efficient dirt removal from effluent and a reduction in treatment costs. An excellent review of wool scouring (and of wool processing generally) up to 1984 is available [146]. 

Carr et al. [2004] studied the incidence of different cleaning procedures on wool. ToF-SIMS analyses performed on the commercially scoured wool (negative ion mode) showed the presence of 18-methyleicosanoic acid thioester species (m/z 341), attributed to the presence of 18-methyleicosanoic acid (18-MEA) which is normally the predominant compound of the surface layer of wool. Other lipids are also detected. After artificial sunlight exposure, analyses show that 18-MEA disappears from the surface. 

It was generally assumed that the endocrine disruptor nonylphenol (NP) is the most persistent metabolite of NPEO. However, experimental data on the formation of the metabolite NP from NPEO are surprisingly scarce, and mostly under anaerobic conditions NP has been reported to be formed [126,127]. Only one article reports a slight increase in NP concentration from the aerobic degradation of NPEO during the composting of wool scour effluent sludge [128]. 

While the formed-in-place or dynamic hydrous zirconium oxide membranes on porous stainless steel supports have been studied mostly for biotechnology applications, they have also demonstrated promises for processing the effluents of the textile industry [Neytzell-de-Wilde et al, 1989]. One such application is the treatment of wool scouring effluent. With a TMP of 47 bars and a crossflow velocity of 2 m/s at 60-70°C, the permeate quality was considered acceptable for re-use in the scouring operation. The resulting permeate flux was 30-40 L/hr-m. Another potential application is the removal of dyes. At 45 C, the dynamic membranes achieved a color removal rate of 95% or better and an average permeate flux of 33 L/hr-m under a TMP of 50 bars and a crossflow velocity of 1.5 m/s. 

Other coco-based surfactants are sulfosuccinates formed by the reaction of coco fatty alcohol with maleic anhydride and further reaction with sodium sulfite or bisulfite. This product possesses good foaming properties, is compatible with soap, and is a good lime dispersant. It is used in toilet soap formulation, shampoos, hand cleaning pastes, and for scouring raw wool. Its ether variant, with 2-4 moles ethylene oxide, forms intense, finely structured foam and is used in combination with ether sulfate in baby shampoos and bath preparations. 

Some of the commercial uses which the machine suggests are the recovery of oil from soap stock, the dehydration of crude petroleum and emulsions, the separation of amorphous wax from cylinder stock and the recovery of wool grease from waste scouring liquors. A brief description of the last application will make the commercial use of the machine plain. 

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