Wastewater, dyes

H.M. Pinheiro, E. Toraud and O. Thomas, Aromatic amines from azo dye reduction Status review with emphasis on direct UV spectrophotometric detection in textile industry wastewaters. Dyes Pigments, 61, 121-139, 2004. 

Uses Thixotrope, defoamer for aq. systems incl. detergents, emulsions, disps., textile auxs., lacquers, paints, wastewater, dyeing processes, distillation... 

Yu, R., Wu, X, Huang, H. 2010. Adsorption of Three Wastewater Dyes by Modified Pineapple Peel Fiber [J], Modem Food Science and Technology 26(7) 674—675. 

Pinheiro HM, Touraud E, Thomas O (2004) Aromatic amines from azo dye reduction status review with emphasis on direct UV spectrophotometric detection in textile industry wastewaters. Dyes Pigments 61 121-139. doi 10.1016/j.dyepig.2003.10.009 Ramalho PA, Helena CM, Cavaco-Paulo A, Teresa RM (2004) Characterization of azo reduction activity in a novel ascomycete yeast strain. Appl Environ Microbiol 70(4) 2279-2288. doi 10.1128/AEM.70.4.2279-2288.2004... 

The pulp and paper industry and potable and wastewater treatment industry are the principal markets for aluminum sulfate. Over half of the U.S. aluminum sulfate produced is employed by the pulp and paper industry. About 37% is used to precipitate and fix rosin size on paper fibers, set dyes, and control slurry pH. Another 16% is utilized to clarify process waters. The alum sold for these purposes is usually Hquid alum. It is frequendy acidic as a result of a slight excess of H2SO4. Aluminum sulfate consumption by the pulp and paper industry is projected to remain constant or decline slightly in the near term because of more efficient use of the alum and an increased use of alkaline sizing processes (13). 

Heavy Metals. Heavy metals of particular concern in the treatment of wastewaters include copper, chromium, 2inc, cadmium, mercury, lead, and nickel. They are usually present in the form of organic complexes, especially in wastewaters generated from textiles finishing and dye chemicals manufacture. 

The widespread use of biphenyl and methyl-substituted biphenyls as dye carriers (qv) in the textile industry has given rise to significant environmental concern because of the amount released to the environment in wastewater effluent. Although biphenyl and simple alkylbiphenyls are themselves biodegradable (48—50), the prospect of their conversion by chlorination to PCBs in the course of wastewater treatment has been a subject of environmental focus (51—53). Despite the fact that the lower chlorinated biphenyls are also fairly biodegradable (49,54,55) continued environmental concern has resulted in decreased use of biphenyl as a dye carrier (see Dyes, environmental chemistry). 

Sodium Tetrahydroborate, Na[BH ]. This air-stable white powder, commonly referred to as sodium borohydride, is the most widely commercialized boron hydride material. It is used in a variety of industrial processes including bleaching of paper pulp and clays, preparation and purification of organic chemicals and pharmaceuticals, textile dye reduction, recovery of valuable metals, wastewater treatment, and production of dithionite compounds. Sodium borohydride is produced in the United States by Morton International, Inc., the Alfa Division of Johnson Matthey, Inc., and Covan Limited, with Morton International supplying about 75% of market. More than six million pounds of this material suppHed as powder, pellets, and aqueous solution, were produced in 1990. 

Foam Fractionation. An interesting experimental method that has been performed for wastewater treatment of disperse dyes is foam fractionation (88). This method is based on the phenomenon that surface-active solutes collect at gas—Hquid iaterfaces. The results were 86—96% color removal from a brown disperse dye solution and 75% color removal from a textile mill wastewater. Unfortunately, the necessary chemical costs make this method relatively expensive (see Foams). 

Although it has been reported (138) that decolorization of wastewater containing reactive azo dyes with sodium hydrosulfite is possible only to a limited extent, others have demonstrated good reduction (decolorization). For example, using zinc hydrosulfite for the decolorization of dyed paper stock (139) resulted in color reduction of 98% for azo direct dyes (139). A Japanese patent (140) describes reducing an azo reactive dye such as Reactive Yellow 3 with sodium hydrosulfite into its respective aromatic amines which ate more readily adsorbable on carbon than the dye itself. This report has been confirmed with azo acid, direct, and reactive dyes (22). 

Oxidation. Oxidation is one of the main chemical methods to treat and decompose dyes in wastewater. The oxidation agents used ate chlorine, bleach, ozone, hydrogen peroxide, Fenton s reagent, and potassium permanganate. 

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