Piezoelectrochemical Effect: A New Mechanism for Azo Dye Decolorization in Aqueous Solution through Vibrating Piezoelectric Microfibers

Abstract

A newly discovered piezoelectrochemical (PZEC) effect for the direct conversion of mechanical energy to chemical energy is applied for the mechanically induced degradation of a dye of C.I. Acid Orange (AO7) from aqueous solution in the presence of BaTiO3 microdendrites. The mechanism of the PZEC degradation of the dye depends on the ultrasonic vibration used, in which the formation of the strain-induced electric charges on the dendrite surface is due to the deformation and local charge accumulation on the BaTiO3. With sufficient applied electric potential, strained piezoelectric dendrites in AO7 aqueous solution triggered the decomposition reaction. The process is monitored by following the decolorization rate of AO7. The effects of pH, catalyst loading, and initial dye concentration on dye degradation were also studied. Kinetic analyses reveal that the PZEC degradation rates of AO7 can be approximated in terms of the Langmuir–Hinshelwood model. The value of the adsorption equilibrium constant, KAO7, was 0.149 (mgl–1)−1, and the value of the kinetic rate constant of the surface reaction, kc, was 0.50 mgl–1 min–1. These new strain-induced chemical reactions can provide a simple and cost-effective technology for decomposing organic pollutants in aqueous solution by scavenging waste energy such as noise or stray environmental vibrations.