Preparation of zinc tungstate nanomaterial and its sonocatalytic degradation of meloxicam as a novel sonocatalyst in aqueous solution.

Zinc tungstate (ZnWO4) was previously used as a photocatalyst. In this paper, for the first time as an sonocatalyst, the performance of ZnWO4 for sonocatalytic degradation of meloxicam (MEL) under ultrasonic irradiation were studied. Firstly, ZnWO4 nanomaterials were synthesized at different acidity (pH = 5, 6, 7, 8, 9) via the hydrothermal method. Utilizing SEM, XRD and EDS techniques to characterize composition and morphology of each product, the same crystal forms, but different morphologies (nano-sheet, nano-microspheres or nano-rod) of ZnWO4 could be obtained. Secondly, the sonocatalytic activities of ZnWO4 on degradation of MEL were studied. It was found that the degradation ratio varied with the synthetic pH values, with ZnWO4 under synthetic pH = 6 exhibiting the best sonocatalytic performance (75.7%). Whilebeing synthesized at this pH value, ZnWO4nano-microspheres had the largest BET surface area (27.068 m2/g), the smallest particle size (40-60 nm) so as to provide more active sites on its surface, which were able to produce more reactive oxygen species (ROS) and holes under ultrasonic irradiation. These ROS and holes had a positive effect on the degradation of MEL into CO2, H2O and inorganic. Thirdly, various influential factors including ultrasonic power intensity, ultrasonic time, catalyst addition dosage, initial concentration of MEL solution and reusability of catalyst were also explored. Under the condition of 10 mg/L MEL concentration, 20 mg catalyst dosage, 120 min irradiation time, 0.278 W/cm2 ultrasonic power intensity, the degradation ratio on MEL reached 75.7%. Finally, the presence of hydroxyl radical (OH) and singlet molecular oxygen (1O2) in the reaction was confirmed by adding ROS scavenger. The experimental results suggested that ZnWO4 nanoparticle could be used not only as an effective photocatalyst, but also, under the condition of ultrasonic irradiation, a promising sonocatalyst for degradation of organic pollutants in aqueous media.

Binding of fluphenazine with human serum albumin in the presence of rutin and quercetin: An evaluation of food-drug interaction by spectroscopic techniques.

The interactions between human serum albumin (HSA) and fluphenazine (FPZ) in the presence or absence of rutin or quercetin were studied by fluorescence, absorption and circular dichroism (CD) spectroscopy and molecular modeling. The results showed that the fluorescence quenching mechanism was static quenching by the formation of an HSA-FPZ complex. Entropy change (ΔS0 ) and enthalpy change (ΔH0 ) values were 68.42 J/(mol⋅K) and -4.637 kJ/mol, respectively, which indicated that hydrophobic interactions and hydrogen bonds played major roles in the acting forces. The interaction process was spontaneous because the Gibbs free energy change (ΔG0 ) values were negative. The results of competitive experiments demonstrated that FPZ was mainly located within HSA site I (sub-domain IIA). Molecular docking results were in agreement with the experimental conclusions of the thermodynamic parameters and competition experiments. Competitive binding to HSA between flavonoids and FPZ decreased the association constants and increased the binding distances of FPZ binding to HSA. The results of absorption, synchronous fluorescence, three-dimensional fluorescence, and CD spectra showed that the binding of FPZ to HSA caused conformational changes in HSA and simultaneous effects of FPZ and flavonoids induced further HSA conformational changes.