Degradation of 4-chloro 2-aminophenol using combined approaches based on microwave and photocatalysis

• Combined strategies based on microwave and photocatalysis for degradation of 4C2AP.
• Controlling mechanism for degradation of 4C2AP is the free radical attack.
• Near complete degradation of 4C2AP is obtained using MW + UV + TiO2 + H2O2.
• Additives can help in reducing energy requirement due to lower treatment times.
• Non-toxicity of the degradation products confirmed using anti-microbial test.

Degradation of 4-chloro 2-aminophenol (4C2AP), a highly toxic organic pollutant, has been investigated using different approaches based on the use of microwave (MW) irradiation, photocatalysis and sequential combination of MW and photocatalysis. Hydrogen peroxide (H2O2) has been used as an additive for intensification of the degradation. The effect of important operating parameters such as initial concentration of 4C2AP, initial pH, power dissipation, TiO2 loading and H2O2 loading on the extent of degradation have been investigated. The obtained optimum conditions as initial concentration of 4C2AP as 20 ppm, initial pH as the natural pH of solution, power dissipation of 8 W for UV irradiation, H2O2 loading as 300 ppm and TiO2 loading as 0.1 g/l have been established for photolysis approach and then subsequently used for the sequential combination of MW and UV. It has been established that maximum degradation of 4C2AP as 93.23% is obtained in the sequential approach of MW and UV with optimized TiO2 and H2O2 loadings. The degradation of 4C2AP followed first order kinetics for all the treatment approaches investigated in the present work. The degradation products of 4C2AP have been identified using GC–MS and the toxicity analysis has also been performed using anti-microbial activity test based on agar-well diffusion method for the degradation products as well as the parent pollutant. The obtained results clearly established that the combined process of MW and UV in combination with TiO2 and H2O2 is most effective approach in the degradation of 4C2AP as compared to individual treatment approaches of MW and UV as well as other combined approaches as MW + TiO2, MW + H2O2, UV + TiO2, UV + H2O2, MW + TiO2 + H2O2 and UV + TiO2 + H2O2.

Comparison of different approaches based on UV irradiations and microwave for the degradation of 4C2AP.Figure optionsDownload as PowerPoint slide