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A comparative study of Cu-impregnated ZnO and Ni-impregnated ZnO for the sonophotocatalytic degradation of cefixime in aqueous solution under visible light irradiation was carried out. Sonophotocatalysts were prepared by using a wet impregnation method and characterised using different spectroscopic techniques. Sonophotocatalytic efficiency of degradation is superior to photolysis, sonolysis, photocatalysis and sonocatalysis. Different operational parameters like pH, catalyst dosage, different enhancers, scavenger's effect, initial concentration of drug, reusability of catalyst and catalyst settling time were optimised. Optimum time of 30 min was found for the 45.7% degradation of cefixime using Cu-ZnO and 42.2% degradation using Ni-ZnO photocatalysts at pH 10. The degradation of cefixime increased from 75.3% to 100% with 5 mmol of hydrogen peroxide using 0.1 g/ L of Cu-ZnO and 99.8% using 0.15 g/L of Ni-ZnO, while other oxidising agents were found less effective using (Cu–ZnO-Ni-ZnO) photocatalyst. A very little decrease in degradation was observed with different types of scavengers. Catalyst reusability was checked up to three cycles and good results up to three cycles were achieved and followed pseudo-first-order kinetic model. Furthermore, the sonophotocatalytic activity was tested for real pharmaceutical wastewater resulting in 91 and 89% removal of total organic carbon (TOC) using (Cu-ZnO-Ni-ZnO), respectively. The proposed method was successfully applied on commercial and synthetic sample with satisfactory results. [ABSTRACT FROM AUTHOR]

Dyestuffs are very persistent in nature and are present in large number in wastewater of different industries. The wastewater of different industries contains many pollutants which are hazardous for human health and environment. In the present study, sonophotocatalytic degradation of Acid red 17 (AR-17) dye in aqueous solution was investigated using silver impregnated zinc oxide (Ag/ZnO). Silver impregnated zinc oxide (Ag/ZnO) catalyst was prepared by wet impregnation method and characterized by SEM, EDX, XRD and band gap. Removal of dye was carried out at 40 kHz frequency ultrasound waves under visible light (Tungsten lamp) of 100 W. The effect of various operating conditions and reagents like H2O2 concentration, pH of the solution, amount of catalyst and concentration of AR-17 dye were investigated. At the own pH of dye using 7 mmole H2O2 concentration 92.9 % degradation of acid red 17 was observed. The degradation increased with increase in irradiation and sonication time of 30 minutes and with 0.25 g /100 mL Ag/ZnO highest degradation 92.94 % was found. The TOC analysis was also carried out sonophotocatalytically and 80 % removal of total organic compounds was observed. The degradation of AR-17 followed pseudo-second-order kinetics with high value of correlation coefficient. [ABSTRACT FROM AUTHOR]

A comparative study of Cu-impregnated ZnO and Ag-impregnated ZnO for the sonophotocatalytic degradation of cefpodoxime proxetil in aqueous solution under visible light irradiation were carried out. Optimum conditions for degradation of cefpodoxime proxetil using Cu-ZnO and Ag-ZnO was investigated. The effect of enhancers and scavengers were investigated using optimum conditions and hydrogen peroxide as enhancers. 100% degradation was achieved using Cu-ZnO and Ag-ZnO. Furthermore, total organic carbon analysis was carried out and 89% using Cu-ZnO and 93% using Ag-ZnO removal of total organic compounds were observed. The sonophotocatalytic degradation of cefpodoxime proxetil using Cu-ZnO and Ag-ZnO followed pseudo-first-order kinetic and the rate of degradation of cefpodoxime proxetil using Ag-ZnO was found higher (k1 = 0.228) than the Cu-ZnO photocatalyst (k1 = 0.185). The method has also been successfully applied in samples for sonophotocatalytic degradation. [ABSTRACT FROM AUTHOR]

To increase the performance of ZnO from UV to visible light, ZnO particles were impregnated with copper (Cu) using wet impregnation method. The synthesized impregnated ZnO was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Fourier transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The degradation of dyes with sonophotocatalytic process was high as compared to photocatalytic and sonocatalytic. The effects of the copper impregnated ZnO (Cu-ZnO) catalyst on the degradation of two textile dyes were investigated using the parameters like pH, catalyst dose, radical enhancer, radical scavenger and initial dye concentration. The addition of radical enhancer (H2O2) increased the degradation efficiency from 35% to 95% at pH 10. At optimum conditions, maximum degradation of dyes were 100% in 20 min using sonophotocatalytic degradation as compared to photocatalytic process the degradation efficiency was 95-98% in 60 min. With the addition of carbonate, sulphate and chloride as radical scavengers, the degradation efficiency decreased from 100% to 92%, 94% and 92% with 0.025 M concentration of each scavenger, respectively. The degradation efficiency decreased only 5% after repeated use of Cu-ZnO catalyst. Therefore, Cu-ZnO catalyst can be used as a promising sonophotocatalyst for degradation of textile dyes with excellent reusability potential. [ABSTRACT FROM AUTHOR]