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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]

Liquid–liquid microextraction method based on supramolecular solvent was proposed for analysis of dinitroaniline herbicides (pendimethalin and trifluralin) residue in water and onion samples. In the present method, reverse micelles of undecanol (250 mg 1-undecanol) dispersed in tetrahydrofuran and water was used as supramolecular solvent. The parameters affecting the extraction efficiency of herbicides like pH, amount of 1-undecanol, percentage of tetrahydrofuran (THF), composition, volume of supramolecular solvent and vortex time were studied. At optimum conditions, the linear range for both herbicides was from 0.03 to 100 mgL−1. The method was found selective for determination of dinitroaniline herbicides in the presence of coextractants of onion samples. The percentage recoveries were found 97.5–100% and 91.2–95.2% for water and onion samples, respectively. Limit of detection (S/N = 3) of pendimethalin and trifluralin was in the range of 3.0–5.5 µgL−1 for water samples and 7–11 µgL−1 for onion samples. Preconcentration factor was found to be 63. Calculated analytical eco-scale value (>75) for the proposed method fulfilling principles of green analytical chemistry. [ABSTRACT FROM AUTHOR]