Sticky removal

The appearance of so-called stickles is described for instance by Hubbe [53], These are most often the result of synthetic polymers used in pressure-sensitive label adhesives. The full characterization of stickles is not easy to assess since there are many different types of stickles that have to be considered [54], 

The existence of primary stickles (from raw materials) and secondary stickles, which were built by the interaction in such systems, has been described, together with many different characterization methods(including mechanical methods) for quantifying the efficiency of different fixing agents [55, 56]. In addition, physicochemical methods such as measuring the cationic demand, the zeta-potential, or the turbidity of wastewater have been applied. 

Unfortunately, none of the sticky test methods investigated was found to be universally apphcable, i.e., suitable for aU types of stickles. Therefore, the most suitable method must be chosen for each particular case and problem area [56]. 

Previous articles or reviews (such as [53, 57]) have considered the origin, the nature, as well as the removal of DCS. 

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Generally, the recycle is similar to mechanical pulping operations but product can be higher quality. De-inking and adhesive ( stickies ) removal are peculiar to recycled pulp. 

A few articles describe the application of starch, modified starch, or other carbohydrate polymers as flocculant for sticky removal [63-66]. The role of charge on the destabilization of microstickies was investigated by Huo by comparing the strong PC... 

Sticky removal with different natural polymers has been compared [69]. Tailored starches, with benzyl as well as with ethyl substituents, from very low to high cationic starch density, were investigated as well as benzylated chitosan. 

Putz HJ, Hamann A, Gruber E (2003) Examination of sticky origin and sticky removal. Wochenbl Papierfabrikat 131 883... 

Petzold G, Petzold-Welcke K, Qi H, Stengel K, Schwarz S, Heinze T (2012) Sticky removal with natural based polymers - highly cationic and hydrophobic types compared with unmodified ones. CarbohydrPolym 90 1712... 

In a 50-100 ml. conical flask place a solution of 0 -5 g. of glucose in 5 ml. of water, 12-15 ml. of 10 per cent, sodium hydroxide solution and 1 ml. of benzoyl chloride, cork tightly, and shake until the odour of benzoyl chloride has disappeared and a crystalline (frequently sticky) soUd has separated. Filter oflF the solid, wash it with a Uttle water, and recrystaUise it from ethyl or n-butyl alcohol. (If the product is sticky, it should be removed, and spread on a porous tile before recrystaUisation.) Glucose pentabenzoate has m.p. 179°. Fructose pentabenzoate, m.p. 78-79°, may be similarly prepared. 

There are some alternatives to this HCI generator type of crystallization. There are, of course, canisters of HCI gas that can be purchased. Also, one can crystallize with very concentrated (fuming) HCI by pouring the stuff directly into the ether/freebase [26]. Regular 35% HCI can do this too, but the water content may dissolve the MDA.HCl or make the crystals sticky which means that the chemist will have to dry the solution by removing the water. 

The carbon black (soot) produced in the partial combustion and electrical discharge processes is of rather small particle si2e and contains substantial amounts of higher (mostly aromatic) hydrocarbons which may render it hydrophobic, sticky, and difficult to remove by filtration. Electrostatic units, combined with water scmbbers, moving coke beds, and bag filters, are used for the removal of soot. The recovery is illustrated by the BASF separation and purification system (23). The bulk of the carbon in the reactor effluent is removed by a water scmbber (quencher). Residual carbon clean-up is by electrostatic filtering in the case of methane feedstock, and by coke particles if the feed is naphtha. Carbon in the quench water is concentrated by flotation, then burned. 

Commercial and Artificial Processing. Commercially, silkworm cocoons are extracted in hot soapy water to remove the sticky sericin protein. The remaining fibroin or stmctural sdk is reeled onto spools, yielding approximately 300—1200 m of usable thread per cocoon. These threads can be dyed or modified for textile appUcations. Production levels of sdk textiles in 1992 were 67,000 metric tons worldwide. The highest levels were in China, at 30,000 t, foUowed byJapan, at 17,000 t, and other Asian and Oceanian countries, at 14,000 t (24). Less than 3000 metric tons are produced annually in each of eastern Europe, western Europe, and Latin America almost no production exists in North America, the Middle East, or Africa. 1993 projections were for a continued worldwide increase in sdk textile production to 75,000 metric tons by 1997 and 90,000 metric tons by 2002 (24). 

Implicit in cake filtration is the removal and handling of solids, since the cake is usually relatively dry and compacted. C es can be sticky and difficult to handle therefore, the ability of a filter to discharge the cake cleanly is an important equipment-selection criterion. 

Removable-Medium Filters Some drum filters provide for the filter medium to be removed and reapplied as the drum rotates. This feature permits the complete discharge of thin or sticky cake and provides the regenerative washing of the medium to reduce blinding. Higher filtration rates are possible because of the thinner cake and clean medium, but this is compromised by a less pure filtrate than normally produced by a nonremovable medium. 

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