Degradation of brilliant green dye using combined treatment strategies based on different irradiations

The present study is based on the use of combination strategies based on sonolysis, photolysis, and microwave applied for wastewater treatment. Brilliant green (BG) dye has been considered as the model pollutant. The operating parameters viz, initial concentration of dye and pH of the solution were optimized for the individual effect of sonolysis, photolysis and microwave. The optimized initial concentration of dye pollutant as 20 ppm and pH of 6.0 was found to be same for all the individual approaches. It has been observed that the first order kinetic rate constant was the maximum for individual microwave (6.1 x 10(-2) min(-1)) and also operation was effective in terms of the energy requirement (maximum degradation efficiency as 2.8 x 10(-8) g/J). The percentage degradation was found to be the maximum for the sequential operation of microwave followed by sonolysis (93.2%) compared to the combination of sonolysis and photolysis (84.5%), and sequential operation of sonolysis followed by microwave (80.6%). The effectiveness of combination and sequential approaches was analyzed based on the kinetic rate constant, percentage degradation, time required for degradation, and energy requirement. The obtained results in the present study indicate that the sequential operation of microwave followed by sonolysis was the most effective approach as compared to the other approaches. A continuous process has been also developed based on the sequential effect and the percentage degradation was found to be same for batch and continuous mode of operation. (C) 2014 Elsevier B.V. All rights reserved.