Degradation of 4-chloro 2-aminophenol using a novel combined process based on hydrodynamic cavitation, UV photolysis and ozone

• A novel combined approach based on hydrodynamic cavitation, photolysis and ozone.
• Optimization of process intensifying parameters gives complete removal of pollutant.
• Combined approach gives best results for degradation with synergism.
• Identification of the degradation intermediates with proposed reaction mechanism.

The degradation of 4-chloro 2-aminophenol (4C2AP), an acute toxic organic compound, has been studied using different approaches based on the hydrodynamic cavitation (HC) with orifice plate as cavitating device, photolysis (UV) and ozonation (O3). The dependency of extent of degradation on operating parameters like operating pressure (2–5 bar), initial pH (3–8) and temperature (30–38 °C) have been established initially to maximize the efficacy of hydrodynamic cavitation. Subsequently the degradation has been studied using combined treatment strategies as HC + UV, HC + O3, UV + O3 and HC + UV + O3 at the established optimum parameters of operating temperature as 30 °C, initial pH of 6 and inlet pressure of 4 bar. The maximum extent of degradation as 96.85% and 73.6% reduction in TOC has been obtained using hydrodynamic cavitation in combination with UV photolysis and ozonation under the optimized operating conditions. The degradation products of 4C2AP have been identified using GC–MS. The present work has clearly established the efficacy of combined treatment approach (HC + UV + O3) for the removal of organic pollutant for the first time.