Liquors tanning

Loh-beize, /. tan liquor tanning, -briihe, /. (Leather) bark liquor, ooze. -brUhleder, n. ooze leather,... 

Abtragimg, /. carrying off, etc. (see abtragen). AbtrankbrUhe,/. (Leather) tan liquor, abtrttnken, v.t. saturate, impregnate (Leather) fill up with tan liquor. 

Gerbbriihe, Gerbebriihe, Gerbeflossigkeit, f. tan liquor, tanner s liquor, ooze. 

Gerber-fett, n. (Leather) d gras, stuff, -hof, m. tan yard, -kalk, m. slaked lime gas lime, -lobe, /. tanbark tan liquor, -strauch, m. tanner s sumac (Rhus coriaria) ink plant (Coriaria). -wolle, /. skin wool, pelt wool. 

Lohe, /. tanbark tan liquor, ooze flame, blaze. 

Stink-farbe, /. old weak tan liquor, -fluss, -flussspat, m. fetid fluor spar (bituminous fluorite), -harz, n. asafetida. -kalk, m. anthraconite (bituminous limestone), ohle, /. fetid coal, -mergel, m. fetid marl (bituminous marl), -ol, n. fetid oil, specif, animal oil. -quarz, m. fetid quartz (bituminous quartz), -raum, m. gas chamber, -raum-probe, /. gas-chamber test, -schiefer, m. fetid shale, -spat, m. = Stinkfluss. -stein. 

The crude acid is dissolved in 500 ml. of petroleum ether at room temperature. The small amount of amorphous solid which may separate is removed by filtration through Supercel, and the filtrate is concentrated under reduced pressure to 300 ml. Chilling to 0-5° yields a first crop of tan crystals which is collected by suction filtration and washed with the minimum amount of ice-cold petroleum ether. Concentration of the mother liquors to 150 ml. and chilling yields a second crop of brownish crystals. The combined crops are dissolved in 300 ml. of petroleum ether, and the light-red solution is chilled to 0-5°. The almost white to light-tan crystals are collected, washed with a small amount of cold petroleum ether, and dried in a vacuum desiccator. There is obtained 51.5—61.5 g. (51-61%) of stearolic acid, m.p. 46-46.5° (Note 5). 

It has been widely known that a water-insoluble gel is obtained when spent sulfite liquors are treated with dichromate solutions. This property has been used, among other things, for increasing the tanning effect of lignosulfonates and for making oil well drilling muds. 

The tan precipitate which forms is removed by filtration and washed with cold water. By diluting the mother liquor with water, a second crop of product may be obtained. Total yield 2.29 gm (81 %). The product, after recrystallization from aqueous methanol, has a decomposition temperature of 168°-169°C. 

Mother liquor at 90% dextrose from the first crop of crystals can be concentrated and crystallized in a similar manner to recover an additional crystal crop. Depending on quality, some mother liquor can be partially recycled to the initial crystallization step to increase crystal-phase yield as a single crystal crop. The overall yield depends on the dextrose content of the original hydrolyzate and the extent to which hydrolyzates are refined. The mother liquor from the second crystallization contains less than 80% dextrose. The material is evaporated to 71% solids and sold as hydrol to the tanning and fermentation (qv) industries and for the manufacture of caramel color. 

Glycidaldehyde has been used as a cross-linking agent for the finishing of wool, for the oil tanning and fat liquoring of leather and surgical sutures (lARC, 1976). 

Adsorption by a solid surface of a solute hi dilute solution is of course the basis of many technical operations, e.g. clarification of industrial liquors, detergency, dyeing, lubrication, tanning, and numerous ion-exchange processes, and is probably operative in most biological systems. 

The most popular tanning solution in current use is termed 33% basic chromium(III) sulfate and corresponds to the empirical formula CrOHSCV In older procedures, chromate was often reduced at the plant using glucose/sulfuric acid mixtures. At present, 33% basic chromium sulfate is provided as either a solution (chrome liquor) or as a commercially available powder,120 of constant, but at present slightly uncertain, chemical composition. 

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