Tannin production

Tannins occur in many plants and are separated by extraction. At present, only quebracho extract is used as a mud thinner in significant quantity in the United States. Quebracho is an acidic material and performs best at high pH. It is an excellent thinner for lime-treated and cement-contaminated muds. However, it is not effective at high salt concentrations. Sulfomethylated tannin products are functional over a wide range of pH and salinity and have either been treated with chromium for good thermal stabiUty (58) or are chrome free. Concentrations of tannin additives are ca 1.5—18 kg/m (0.5—6 lb/bbl). 

The 50%-strength liquid tannin products are particularly viscous, and some sediment is to be expected because of limited solubility of certain constituents at high strength (ellagic acid ). Tannins stored in drums should be mixed before use or before transfer into a day tank. 

Tannins are typically used in BW at 150 to 200 ppm active tannin product, but perhaps only a third of this is related to its polymeric sludge conditioning functionality. 

It is not usual for unopened drums of nitrite-based chemical to degrade, and the product should remain in good condition for several years. However, it is possible for tannin-based corrosion inhibitors to degrade, even in unopened drums. Under warm conditions (such as storage in a boil-erhouse) and in the absence of a small amount of suitable microbiocide in the formulation, plastic drums containing tannin products may swell considerably because of microbiological degradation and gas formation. Care is needed to avoid accidents. 

Wrangham, R. W. and Waterman, P. (1981). Feeding behavior of vervet monkeys on Acacia tortilis and Acacia xanthopbea with special reference to reproductive strategies and tannin production. Journal of AnimalEcology 50,715-731. 

The wood or bark for tannin production is reduced to chips and shreds by passing the material through hoggers or hammer mills. Then it is extracted with warm water in diffusion batteries. The dilute solutions are evaporated to the desired concentration. Loss of solubility of the tannin can be counteracted by treatment of the concentrate with sodium sulfite. 

There are a few minor wood-based chemical industries. After chestnut blight wiped out the American chestnut, U.S. tannin production essentially ceased. The main natural tannins, watde and quebracho, are now imported. High U.S. labor costs and the advent of synthetic tannins make re-establishment of a U.S. tannin industry unlikely. Tannins are used in oil-weU drilling muds. Tree exudates are a continuing wood-based chemical industry. Tree exudates include mbber, tme carbohydrate gums (eg, acacia gum), kinos (eg, the phenolic exudates from eucalyptus), balsams (eg, Storax from l iquidambar spp.), and many different types of oleoresins (mixtures of a soHd resin and a liquid essential oil). The most important oleoresin stiU collected in the United States is pine gum (rosin plus turpentine). 

Fig. 2 Time course of tannin production of adventitious root cultures of Sanguisorba officinalis.

To determine the effects of the constituents in the culture medium on phenolic (tannin) production in G. thunbergii hairy roots, two culture media were prepared one consisted of 1/2 MS major and minor elements (inorganic elements) and B5 vitamins (named as "1/2 MS vB5") and the other B5 major and minor elements and MS vitamins (B5 vMS). The hairy roots (ca 70 mg, fw) subcultured in 1/2 MS and B5 liquid media, respectively, were inoculated into four hormone-free liquid media (1/2 MS, B5, 1/2 MS vB5 and B5 vMS). After four week-culture in the dark at 25 C, the contents of 1, 2, 5, 6, 12 and 13 in these hairy roots were determined by HPLC (Table 5). 

Time. Albumoses precipitated hy tannin. Products, not precipitable. formed per hour. 

Ross, M. D. and W. T. Jones, A genetic polymorphism from tannin production in Lotus corniculatus and its relationship to cyanide polymorphism, Theoret. Appl. Genet., 64, 263-268 (1983). 

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