Decolorization and destruction of metallophthalocyanines in aqueous medium by ultrasound: a feasibility study

Most currently available treatment methods for the phthalocyanine type of pigments have shortcomings and problems. An alternative approach using chemical-assisted ultrasound was conducted and the feasibility for the decolorization and destruction of the metallophthalocyanines has been demonstrated. Both copper and nickel phathlocyanine, with water and organic solvents at ambient temperature and atmospheric pressure in the presence of catalytic amount of oxidant under 20 kHz of frequency at a power level of 37–59 W/cm2, can reach a destructive level of 92–95% within 50 min. Preliminary kinetic studies found that the process belongs to the Langmuir-Hinshelwood type. The reaction mechanism is similar to that of metalloporphyrins, and the intermediate is an unstable ion radical that can release metal. Key words: metallophthalocyanines, ultrasound, decolorization, destruction, demetallation, dyebath wastes.