Ultrasonic irradiation effects on electrochemical synthesis of ZnO nanostructures

Two ultrasonic applications for the synthesis of nanostructured copper oxide (II)

In this paper, we present two aspects of the ultrasonic for the synthesis of CuO (II) nanostructures. In the first ultrasound application, we made a copper tip for an ultrasonic probe transducer and used it for electrolysis and ultrasound irradiation processes. This method is named direct sonoelectrochemistry and compares with conventional electrochemistry. CuO (II) nanostructures are obtained after sintering for both direct sonoelectrochemistry method and conventional electrochemistry method. In the second application of ultrasound, the copper nanostructures were generated by the ultrasound ablation method, and then, the heating process was performed for oxidation. The formation of the copper and CuO (II) nanostructures is confirmed by the powder X-ray diffraction (XRD), the field emission electron microscopy (FESEM), and transmission electron microscopy (TEM). The results show that the direct sonoelectrochemistry method generates CuO (II) nanostructures 4.2 times more than conventional electrochemistry. The crystallite size in the electrochemistry methods and direct sonoelectrochemistry is 28.44 nm and 26.60 nm, respectively. The direct sonoelectrochemistry way is a very flexible method and parameters in electrochemical, ultrasound, and the relationship between them can play an important role in the process of synthesis of nanostructures. The crystallite size in the ultrasound ablation method is 21.13 nm and 25.23 nm for the copper and CuO (II) nanostructures. The most important advantages of this method are green, fast, and high purity of the produced nanostructures.

A novel technique to generate aluminum nanoparticles utilizing ultrasound ablation

In the present article, a novel method of ultrasound ablation technique is presented with the experimental results for the generation of the aluminum nanoparticles. The formation of the aluminum nanoparticle is confirmed by; the powder X-ray diffraction (XRD), the field emission electron microscopy (FESEM), the atomic force microscopy (AFM) and transmission electron microscopy (TEM). The most probable particle size of nanoparticles produced by this method is 44.7 and 105.7 nm for two different ultrasonic power of 20 W and 50 W respectively. The ultrasonic ablation method is an innovative method for the production of aluminum nanoparticles. In this method, the fast movement sanding by an ultrasonic apparatus converts aluminum foil to nanoparticles. The most important advantages of this method are green, fast, controllable, and high purity of the produced nanoparticle.

Organic-Inorganic Nanohybrid Electrochemical Sensors from Multi-Walled Carbon Nanotubes Decorated with Zinc Oxide Nanoparticles and In-Situ Wrapped with Poly(2-methacryloyloxyethyl ferrocenecarboxylate) for Detection of the Content of Food Additives

An electrochemical sensor for detection of the content of aspartame was developed by modifying a glassy carbon electrode (GCE) with multi-walled carbon nanotubes decorated with zinc oxide nanoparticles and in-situ wrapped with poly(2-methacryloyloxyethyl ferrocenecarboxylate) (MWCNTs@ZnO/PMAEFc). MWCNTs@ZnO/PMAEFc nanohybrids were prepared through reaction of zinc acetate dihydrate with LiOH·H2O, followed by reversible addition-fragmentation chain transfer polymerization of 2-methacryloyloxyethyl ferrocenecarboxylate, and were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Raman, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), scanning electron microscope (SEM), and transmission electron microscope (TEM) techniques. The electrochemical properties of the prepared nanohybrids with various composition ratios were examined by cyclic voltammetry (CV), and the trace additives in food and/or beverage was detected by using differential pulse voltammetry (DPV). The experimental results indicated that the prepared nanohybrids for fabrication of electrochemical modified electrodes possess active electroresponse, marked redox current, and good electrochemical reversibility, which could be mediated by changing the system formulations. The nanohybrid modified electrode sensors had a good peak current linear dependence on the analyte concentration with a wide detection range and a limit of detection as low as about 1.35 × 10-9 mol L-1, and the amount of aspartame was measured to be 35.36 and 40.20 µM in Coke zero, and Sprite zero, respectively. Therefore, the developed nanohybrids can potentially be used to fabricate novel electrochemical sensors for applications in the detection of beverage and food safety.

Experimental studies on the effect of ultrasonic waves on single drop liquid-liquid extraction

The influence of ultrasonic waves on hydrodynamics and mass transfer of circulating drops in liquid-liquid extraction process was studied. The recommended chemical systems of toluene-acetic acid-water with mass transfer resistance mainly in the organic phase, and cumene-isobutyric acid-water in the aqueous phase were used. An extraction column, equipped with an ultrasonic emitter of 35.40kHz real frequency and 0.37mW/cm² intensity, was employed. The ultrasound properties were measured using the hydrophone standard method. Drops terminal velocity was comparable with the Grace model. In mass transfer study, significant enhancement was revealed in overall mass transfer coefficient for different drop sizes and for the both mass transfer directions by using ultrasonic waves. The average and maximum enhancements were, respectively, 20.8 and 31.7% for toluene-acetic acid-water, and 40.3 and 55.1% for cumene-isobutyric acid-water. Small drops exhibited a higher enhancement percentage. Regarding the mass transfer direction, the system of cumene-isobutyric acid-water with continuous to dispersed phase direction, was benefited more as the consequence of creating effective agitation in continuous phase than in dispersed phase.

High quantum yield ZnO quantum dots synthesizing via an ultrasonication microreactor method

Green emission ZnO quantum dots were synthesized by an ultrasonic microreactor. Ultrasonic radiation brought bubbles through ultrasonic cavitation. These bubbles built microreactor inside the microreactor. The photoluminescence properties of ZnO quantum dots synthesized with different flow rate, ultrasonic power and temperature were discussed. Flow rate, ultrasonic power and temperature would influence the type and quantity of defects in ZnO quantum dots. The sizes of ZnO quantum dots would be controlled by those conditions as well. Flow rate affected the reaction time. With the increasing of flow rate, the sizes of ZnO quantum dots decreased and the quantum yields first increased then decreased. Ultrasonic power changed the ultrasonic cavitation intensity, which affected the reaction energy and the separation of the solution. With the increasing of ultrasonic power, sizes of ZnO quantum dots first decreased then increased, while the quantum yields kept increasing. The effect of ultrasonic temperature on the photoluminescence properties of ZnO quantum dots was influenced by the flow rate. Different flow rate related to opposite changing trend. Moreover, the quantum yields of ZnO QDs synthesized by ultrasonic microreactor could reach 64.7%, which is higher than those synthesized only under ultrasonic radiation or only by microreactor.

Electrospun composite nanofibers of poly vinyl pyrrolidone and zinc oxide nanoparticles modified carbon paste electrode for electrochemical detection of curcumin

A simple and novel ferrocene-nanofiber carbon paste electrode was developed to determine curcumin in a phosphate buffer solution at pH=8. ZnO nanoparticles were produced via a sonochemical process and composite nanofibers of PVP/ZnO were prepared by electrospinning. The characterization was performed by SEM, XRD and IR. The results suggest that the electrospun composite nanofibers having a large surface area promote electron transfer for the oxidation of curcumin and hence the FCNFCPE exhibits high electrocatalytic activity and performs well in regard to the oxidation of curcumin. The proposed method was successfully applied for measurement of curcumin in urine and turmeric as real samples.

Fast synthesize ZnO quantum dots via ultrasonic method

Green emission ZnO quantum dots were synthesized by an ultrasonic sol-gel method. The ZnO quantum dots were synthesized in various ultrasonic temperature and time. Photoluminescence properties of these ZnO quantum dots were measured. Time-resolved photoluminescence decay spectra were also taken to discover the change of defects amount during the reaction. Both ultrasonic temperature and time could affect the type and amount of defects in ZnO quantum dots. Total defects of ZnO quantum dots decreased with the increasing of ultrasonic temperature and time. The dangling bonds defects disappeared faster than the optical defects. Types of optical defects first changed from oxygen interstitial defects to oxygen vacancy and zinc interstitial defects. Then transformed back to oxygen interstitial defects again. The sizes of ZnO quantum dots would be controlled by both ultrasonic temperature and time as well. That is, with the increasing of ultrasonic temperature and time, the sizes of ZnO quantum dots first decreased then increased. Moreover, concentrated raw materials solution brought larger sizes and more optical defects of ZnO quantum dots.