Initial temperature and concentration effects on dyes destruction rate in their mixtures by underwater discharge

Chemical processes in aqueous solutions under electrical discharge are very interesting both in chemical and ecological terms. The plasma zone presence in the bulk solution intensifies chemical processes, some parameters influencing the rate of chemical reaction (e.g. temperature, concentration, presence of other components in a solution). Organic compounds removing from water is always a destruction process being accompanied in most cases by formation of small toxic components such as phenols and their derivatives.

Destruction degree of organic compounds was found to depend on the concentration. In solutions with one component the increasing concentration causes decreasing in destruction extent.

The mixture of Rhodamine 6G and Direct Blue dyes was used as a working solution, the Direct Blue dye amount being varied with reference to Rhodamine 6G. The initial temperature of the working solution was changed in the range of 10-800C. The dye mixture in the solution was treated by underwater electrical discharges (work voltage did not exceed 900 V). Destruction of dyes was registered by spectrophotometric and chemical methods.

Experimental results showed that the amount of Direct Blue dye influenced the rate of destruction of Rhodamine 6G. The latter decreased at the growing Direct Blue dye concentration since the destruction rate of blue dye increased at 200C. The increase of initial temperature was not observed to result in changes in absorption spectra of the working solution though effecting destruction rates of both dyes. Rhodamine 6G dye destruction rates slowed down at initial temperature rising, those of Direct Blue dye depending on its concentration. The increase of the initial temperature was revealed not to affect the destruction rate in the solution with a small amount of this dye. However, rising in temperature caused increasing rate of dye’s destruction at concentration of 8 mg/L, these effects being explained by chemical processes in the solution.

Grosheva A. K.