Intensification of e xtraction of na tural raw mat erials for wool yarn dyeing

Agriculture and food processing industry, during the basic production process, generate a large amount of organic waste, many of which contain coloring pigments and are a inexpensive source of raw materials for the technology of natural dyeing of textile materials. Their rational use will solve the problem of waste disposal. A technology for dyeing wool yarn with black grape pomace from winemaking, extracted from zoned grape varieties of the Vitebsk region, is proposed. The pomace contains pulp, skin and seeds of grapes, used after the fermentation process of winemaking, in fresh form. It is known that the brightness of the yarn color is affected not only by the temperature and duration of the dyeing stage, the presence of mordants, but also by the technological modes of the process of extracting the dye from the raw material, the concentration of the dye in the working bath. The aim of the study was to determine the optimal mode of grape pomace extraction to obtain a natural dye, to define the pattern of color change in dyed yarn based on the concentration of raw materials and pH of the environment. It was found that high extraction temperature leads to degradation of phenolic pigments and it is difficult to obtain yarn with more saturated colors. The acidic environment of the dye bath improves the dyeability of the yarn. With an increase in pH to 6, a deterioration in the color intensity is noted with its transition to a yellow-green range, since anthocyanin pigments of grape pomace undergo reversible structural transformations with a change in pH. The formation of complexes of anthocyanins with metal cations (when using mordants) affects the color, the monovalent cation K+ produces purple complexes. The research results can be recommended for application in dyeing wool yarn with food processing industry waste resulting from berry processing (black currant, chokeberry).