Printing and dyeing wastewater is harmful to China's current major, one of refractory industrial wastewater, the main pollutants are dyes, sizing, additives, fiber impurities, oil, acid and inorganic salts. Characterized by large waste water, water complex, high concentrations of organic, biodegradable, color depth, water quality changes quickly without the law and so on, especially in the dye of the most polluted. The residual dye components even in small concentrations, can also cause water transmittance decreased, resulting in ecological Environment Damage.
Currently the treatment of dyeing wastewater and more dominated by biochemical and some are supported by the chemical method, but the prevailing cost of handling a large investment, operating costs are high, treatment results are poor, difficult color to remove the disadvantages. On this basis, using physical and chemical treatment methods of study more. By coagulation, chemical oxidation, adsorption and Membrane Technology can remove some of COD and color, which degree of oxidation on the removal of the most obvious. However, oxidation by-products (such as organic halides and epoxides) or operating costs and other issues make the use of chlorine and ozone has been limited.
Chlorine dioxide as a kind of strong oxidation and oxidation of organic halides in the few resulting oxidant in the oxidation of water disinfection and paper and pulp bleaching industry and other industries has been widely used. In recent years, a new oxidant Cl02 people in wastewater treatment were also studied, and useful to Cl0 2 Directly address the report printing and dyeing wastewater. In this paper, chlorine dioxide Dyeing Wastewater Treatment Application of current research and development trend of the mechanism are reviewed and discussed.
1Cl0 2 Properties and bleaching mechanism
1.1Cl0 2 The nature of the
Cl02 is a class of chlorine gas, dissolved in water increase with the concentration of the color from yellow to green to orange red. In the 20cc, air pressure, water, chlorine dioxide concentration of 70mg / L. Chlorine dioxide gas at room temperature compressibility for the liquid density 2.4kg / L, boiling point of 11oC, melting point of a 59cc. Cl02 extremely unstable, volatile, decomposition, usually takes the C10, the first made of the stability of aqueous solution, the use of on-site Coupled with acidic activator after use or take C10: generator on-site plus a direct vote. For Drinking water And Sewage Processing, chlorine dioxide in solution form. Decolorization mechanism
Cl02 treatment of dyeing wastewater oxidation damage mainly to dye the hair color groups and help groups to achieve a significant bleaching effect. Under certain conditions, chlorine dioxide, with DPD (N, N 12-ethyl-p-phenylenediamine), cresol red (o-cresol sulfur phthalate), chlorophenol red (dichloro-sulfur phthalate), acid indigo (5 , 5 an indigo sulfonate, or salt, indigo San Juan, PR), Lisi amine Green B (aryl methane dye), Rhodamine B (tetraethyl Jiluodanming) and methylene blue color agent such as discoloration occurs. Indigo acid in pH <4 when the oxidant chlorine dioxide can break chain reaction, and form a stable compound isatin C8H5NO2. Chlorine dioxide addition and the reaction of acid dyes such as indigo but also with many direct dyes and reactive response, Er Shi dye fade. The nature of the use of chlorine dioxide, chlorine dioxide can be used for treatment of dyeing wastewater. At present, the use of chlorine dioxide for treatment of dyeing wastewater has been some progress, especially in the high removal rate Decolorization and therefore has broad application prospects of.