Tannin solutizing

Tannin solutizer process. In this process, alkyl phenols or isobutyric acid is used in combination with tannic acid and caustic solution. The spent tannin solution is again regenerated by air blown into the solution. 

Figure 19.4 shows the SEM micrographs of the mst surfaces before and after immersion in the mangrove tannin solution at pH 4.0. The pre-rusted sample shows basically coral-like stractures distributed in a random matmer. This stracture disappeared with the tannin treated samples and was replaced by a coarse layer with cracks of irregular shapes. A closer inspection of the surface of each crack revealed tiny flowered-like stmctures stacked on top of one another. Unconverted mst stmctures were observed underneath the transformed tannins. 

Mutual precipitation of oppositely charged dye-stufifs is the basis of a number of volumetric processes of estimation thus the evaluation of tannin solutions may be accomplished with night blue or of eosine with night blue. 

Tin total residue obtained from 50 er. ui Ihe original tannin solution, and dried at 105" (, is also usn-rlniiied. On now ealeulating the residue lor 2110 ev. of tmuiin. -.011111011. and deducting this from tlx tolnl residue left from 11 u liinniu solution (j-euted with the aluminum oxide, tin result should show that 1 gm. of nlmuiuuni oxide absorbs I), It) to 0.50 gm. of tannin. 

One hundred milliliters of a 0.001% solution of tetrachloroauric (III) acid (or silver nitrate) in distilled water ia treated with several drops of 1% sodium carbonate 10-hydrate and heated to boiling in a flask. Every 30 seconds one drop of a fresh 1% tannin solution (XJ.S.P.) is added with agitation. When a deep red gold color has formed (or yellow-brown to red-brown for the silver) the colloidal solution is cooled and stabilized by the addition of a few milliliters of chloroform or toluene. 

Ferric alum. A i" solution is used. To 2-3 c.c. of the tannin solution in a test-tube the reagent is added little by little, excess being avoided the immediate coloration is noted. 

Hr online water. This should be saturated and is added drop by drop to 2-3 c.c of the tannin solution until the latter has a distinct odour of bromine any formation of precipitate, either immediately or after a time, is noted. 

Stannous concentrated solution of stannous chloride in... 

Pinewood and hydrochloric acid. A shaving of deal is dipped into the tannin solution and then moistened with concentrated hydrochloric add to see if it becomes red or violet such coloration may be manifested either at once or only after some hours. 

Sodium sulphite. A crystal of this salt, placed on a flat porcelain dish, is moistened with a few drops of the tannin solution and any coloration noted. 

Sulphuric acid. About 1 c.c. of concentrated sulphuric acid is carefully added to a few drops of the tannin solution in a test-tube so that the liquids do not mix. The coloration formed at the zone of contact of the two liquids is observed and also that subsequently obtained on mixing and diluting. 

Lime water. Excess of lime water is added to a little of the tannin solution in a flat porcelain dish, any formation of precipitate or coloration being noted, as well as the variations occurring therein after some time. 

Sugars may be tested for with Fehling s solution in the tannin solution treated with lead acetate and then with sodium sulphate and subsequently inverted. Since, however, tanning materials generally contain a certain quantity of reducing sugars, addition of glucose cannot always be proved by a mere qualitative test,... 

The effluent is first caught in a beaker—until a drop of it falls to turn turbid with a dear tannin solution as a rule at least 30 c.c. must be collected. 

Tannin solution (10 grams of tannin and 10 grams of sodium acetate iu 100 c.c. of water). 

Tannin test for basic dyestuffs. The extract obtained with formic acid is shaken with a few drops of tannin solution, and if no precipitate forms immediately, the liquid is left at rest for a few minutes. Certain colouring matters, such as the rhodamines, the gallocyanins and the chrome colours of the rosaniline series (containing carboxyls or hydroxyls besides the basic groups) precipitate slowly and the precipitate, being highly subdivided, is sometimes difficult to see. 

The colour is completely or largely stripped, giving a coloured acid extract, which is precipitated by tannin solution Basio Dyestuff. Transfer to wool and boil with Hydrosulphlte B. 

Some studies have been made relating specifically to astringency. Some of these studies have focused directly on interactions between tannins and salivary proteins [21, 23, 25, 46, 50-53], and on the changes in saliva protein composition after interaction with tannins [15, 38, 54, 55]. Other studies have correlated the sensorial astringency with protein-tannin interactions [45, 56, 57]. In fact, the astringency felt when sampling different tannin solutions can be correlated with the ability of these tannins to precipitate proteins. This effect has been observed with several proteins such as mucin [45], ovalbumin and gelatin [57], bovine semm albumin (BSA), and salivary proteins [58]. 

Figure 16.8 shows a typical flow nephelometric graphic involving the interactions between three substrates protein, tannin, and carbohydrate. In an initial phase there is an increase in turbidity corresponding to the stabilization of protein and tannin concentrations. The maximum value of turbidity corresponds to the TSA of the tannin solution in relation to the protein (BSA). In a second phase a gradient of increasing carbohydrate concentration is started, leading to a decrease... 

In the use of spraying blenders, the following technique can be successfully applied. All the paraformaldehyde powder hardener and 30% of the tannin adhesive spray-dried powder is removed from the liquid glue mix. The paraformaldehyde and wattle adhesive powder are then added to the wood chips just before the adhesive blender where the liquid glue mix is sprayed onto the wood particles. Core material MCs of 10 to 12% and face material MCs of 20 to 22% can then easily be achieved in spite of the high viscosity of tannin solutions. The percentage of paraformaldehyde used should be 14% based on wattle extract solids. The adhesive pH should be, in optimal cases, 6.5 to 6.7 for face material and 6.9 to 7.3 for core material. The percentage of resin solids on dry wood should be 11% for core material and 14 to 18% for face material. 

Mix 2 drops 5 per cent tannic acid (tannin) solution with 2 drops 20 per cent silver nitrate solution, and place the mixture upon drop-reaction paper or upon a little cotton wool. Hold the paper in the vapour produced by heating an ammonium salt with sodium hydroxide solution. A black stain is formed on the paper or upon the cotton wool. The test is a sensitive one. 

A therapeutic preparation of colloidal silver is known as collargol. Crede s ointment also contains this form of silver, and is employed in the treatment of certain types of septic infection. An astringent antiseptic is prepared by the action of an alkaline tannin solution on aqueous solutions of silver salts.11... 

Technical Observations. Large scale preparations use tannin solutions which are obtained by countercurrent extraction of the tannin-containing material with... 

Internal use is in the treatment of catarrh of the stomach and as an antidiarrheal. Not all tannins are suitable for all uses. In the treatment of large burns, tannins are absorbed in such large quantities that they can cause serious damage to the liver. That is the reason why large burns are not treated with tannin solution any more. 

Table 2. Hyperchromic effect (measured at 523 nm) of grape seed tannin fraction on MaIvidin-3-Glucoside in tartrate buffer (pH 3.5). mOP is the mean degree of polymerization measured by diioacidolysis. r the molar ratio between tannin and anthocyanin (a fixed concentration of 1 g/1 of tannin was used). T is the absorbance of tannin solution (control) at 523nm.

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