Removal of tannins

Murugananthan, M., G. Bhaskar Raju, and S. Prabhakar. 2005. Removal of tannins and polyhydroxy phenols by electro-chemical techniques. J. Chem. Technol. Biotechnol. 80 1188-1197. 

Either straightforward drainage or blowdown can readily remove sludge from the plant. It is, however, necessary in some cases to ensure that the residual solids are free-flowing this is achieved by the use of tannin, lignin, seaweed derivatives, and starch organics. 

Other aquatic weeds such as reed mat, mangrove (leaves), and water lily (Nymphaceae family plants) have been found to be promising biosorbents for chromium removal. The highest Cr(III) adsorption capacity was exhibited by reed mat (7.18 mg/g), whereas for Cr(VI), mangrove leaves showed maximum removal capacity (8.87 mg/g) followed by water lily (8.44 mg/g). It is interesting to mention that Cr(VI) was reduced to Cr(III), with the help of tannin, phenolic compounds, and other functional groups on the biosorbent, and subsequently adsorbed. Unlike the results discussed previously for the use of acidic treatments, in this case, such treatments significantly increased the Cr(VI) removal capacity of the biosorbents, whereas the alkali treatment reduced it.118... 

Much work has been done on the removal of Pb and Zn from aqueous solution. Removal of these ions has been attempted by several researches employing a wide variety of techniques. Adsorption of removal of Pb and Zn from solution agricultural waste [5], three fern [6], tannin gel [7], removal of Pb sea module [8], tannin gel adsorbent synthesized from condensed tatmin [8] and removal of Zn green macro alga [9], soil [3] have been extensively studied for this purpose. 

Leaves of Sumac were used for removal of ions in aqueous solution. Tannins were extracted from the leaves of sumac by extracting with 70% (v/v) acetone-water solution. For the total tarmin determination Folin-Ciocalteu method was used and tannin content was found 27%. Various adsorption parameters for the effective removal of Cu + ions by using sumac leaves as an adsorbent from aqueous solutions were studied and optimized. 

We have employed two different protocols for the chemical fractionation of GSE obtained from MegaNatural-AZ based on the amounts needed for bioactivity-based assays. Batches of GSE (50 g) were extracted in acetone/water (7 3) under N2 with mechanical agitation for 12 h. The acetone was removed on a rotary evaporator and the aqueous phase was freeze-dried to yield 48 g of tannin crude extract (TCE). TCE was further fractionated following two different methods. 

Wall ME, Wani MC, Brown DM, et al., Effects of tannins on screening of plant extracts for en2yme inhibitory activity and techniques for their removal. Phytomedicine 5-.2% —2%5, 1996. 

This is based on the method by Van Soest and Wine (1967) which has been modified according to subsequent recommendations. It is the only fibre determination suitable for non-ruminants. The residue consists of the plant cell-wall constituents cellulose, hemicellulose, lignin, cutin, NDF-insoluble tannin and ash. See the article by Cherney (2000) for current modifications these include the use of amylase to aid in the removal of starch from forages containing grain (Van Soest et al., 1991), which has been adopted by MAFF... 

In train oil the impurity is not mucus, as in the vegetal oils, but animal gelatin or glue, and, besides this, volatile, stinking matters. Some clarifiers use a solution of tannin for purifying ft, whioh forms with the gelatin insoluble flakes others employ metallic salts, as sulphate of copper or acetate of load, which act in a similar manner, The nauseous odor 1b most easily removed by bleachfng-powder.—Knapp,... 

John OxlAnd patents acetate of alumina boiled with sugar at 220° till the acid is removed. The alumina remaining is removed by tannin and a little... 

The 55% ethanol extracted 6.91% of the weight of average oven-dry American oak (Table III). In flavoring 1 liter of California port wine for one taster, an average of 575 mg of this wood, 38 mg of its solid, or 13 mg of its phenols extractable by 55% alcohol produced a just detectable difference. A series of five samples of European oak in comparable analyses averaged 11.37% extractable solids, and 1 liter of the same port wine was just detectably flavored by 515 mg of oven-dry wood, 51 mg of extractable solid, or 30 mg of phenol. The fact that European oak contributes more extract and more tannin to wine and yet, per unit of extract or phenol, less flavor is clear from these data. This agrees with tasters opinions and is believed to be because American oak contributes considerably more oak odor per unit of tannin. The amount of flavor per unit of wood is about the same, but the European oak counteracts less flavor per unit of extract by its high extract content. In other tests, 12% alcohol removed 49% as much extract as did 55% alcohol from American oak and 71% as much from French. In earlier tests (47) about 63% as much extract was obtained from American oak by 12% alcohol as by 55% alcohol. Whether these extracts would have the same flavor value has not yet been studied. 

Most other colouring matters withstand the action of the salted caustic soda, but some mordant colours, such as Turkey red, are partly decomposed by it. In these last cases, therefore, the extract obtained with acetic or formic acid does not usually exhibit the colour of the sample under investigation. In order to avoid any possibility of error, when the colouring matter has been removed in appreciable quantity, it is advisable to add a solution of tannin to the acid extract in presence of a basic colouring matter, a precipitate will be formed. 

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