PERFORMANCE EVALUATION OF TREATMENT OF DYING WASTEWATER BY PRACTICAL AND THEORETICAL ANALYSIS

Abstract

DYE is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber. 1.1 DYE TYPES 1.1.1 Acid dyes are water-soluble anionic dyes that are applied to fibers such as silk, wool, nylon and modified acrylic fibers using neutral to acid dye baths. Attachment to the fiber is attributed, at least partly, to salt formation between anionic groups in the dyes and cationic groups in the fiber. Acid dyes are not substantive to cellulosic fibers. Most synthetic food colors fall in this category. 1.1.2 Basic .dyes are water-soluble cationic dyes that are mainly applied to acrylic fibers andalso used for wool and silk. Usually acetic acid is added to the dye bath to help in the uptake of the dye onto the fiber. Basic dyes are also used in the coloration of paper. 1.1.3 Direct or substantive dyeing is normally carried out in a neutral or slightly alkaline dye bath, at or near boiling point, with the addition of either sodium chloride (NaCI) or sodium sulfate (Na2SO4). Direct dyes are used on cotton, paper, leather, wool, silk and nylon. They are also used as pH indicators and as biological stains...........................