Degradation performance of a Keggin type Zn–Mo–Zr catalyst for acidic green B with ultrasonic waves

Abstract

A new heteropolyacid salt, Na₆[Zn(Mo₁₁ZrO₃₉)]·20H₂O, with a Keggin structure of the 1 : 1 : 11 series was synthesized via a classic acidification method, and characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transform infrared (FT-IR) spectroscopy, ultraviolet (UV) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and scanning electron microscopy (SEM). Acidic green B (AGB) was applied to examine the degradation performance of the catalyst which was promoted by ultrasonic waves. The effects of the operating parameters, such as the catalyst dosage, ultrasonic power, medium ultrasonic frequency, initial dye concentration and pH value on the degradation are discussed. In the experiments, the degradation rate reached up to 95.72% under the optimum conditions, i.e. a catalyst dosage of 0.8 g L⁻¹, an AGB concentration of 10 mg L⁻¹, an ultrasonic frequency of 45 kHz and an ultrasonic power of 100 W in just 60 minutes.