Jerry J. Wu

Sonochemical synthesis of CuO nanostructures with different morphology.

This paper describes a highly efficient and rapid approach of synthesizing different CuO nanostructures in aqueous solutions using ultrasound irradiation of copper(II) acetate with urea/sodium hydroxide in the presence of polyvinylpyrrolidone (PVP), as stabilizing polymer. Field emission scanning electron microscope images clearly indicate the formation of CuO quasi-spherical microarchitectures and long-straw like structure in the presence of urea and sodium hydroxide. Other characterization techniques such as TEM, XRD and XPS are also provided to support the formation of such structures. One of the reasons for the formation of such CuO nanostructures may be due to the formation of a polymer-metal complex with the stabilizing polymer (PVP).

Sonochemically synthesized MnO2 nanoparticles as electrode material for supercapacitors.

In this study, manganese oxide (MnO2) nanoparticles were synthesized by sonochemical reduction of KMnO4 using polyethylene glycol (PEG) as a reducing agent as well as structure directing agent under room temperature in short duration of time and characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), Transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis. A supercapacitor device constructed using the ultrasonically-synthesized MnO2 nanoparticles showed maximum specific capacitance (SC) of 282Fg(-1) in the presence of 1M Ca(NO3)2 as an electrolyte at a current density of 0.5mAcm(-2) in the potential range from 0.0 to 1.0V and about 78% of specific capacitance was retained even after 1000 cycles indicating its high electrochemical stability.

Recent Developments in Homogeneous Advanced Oxidation Processes for Water and Wastewater Treatment

This paper reports on recent developments in homogeneous Advanced Oxidation Processes (AOPs) for the treatment of water and wastewater. It has already been established that AOPs are very efficient compared to conventional treatment methods for degradation and mineralization of recalcitrant pollutants present in water and wastewater. AOPs generate a powerful oxidizing agent, hydroxyl radical, which can react with most of the pollutants present in wastewater. Therefore, it is important to discuss recent developments in AOPs. The homogeneous AOPs such as O3, UV/O3, UV/O3/H2O2, and UV/H2O2, Fe2

Investigation on photocatalytic potential of Au–Ta2O5 semiconductor nanoparticle by degrading Methyl Orange in aqueous solution by illuminating with visible light

A semiconductor photocatalytic process has shown great potential as a low cost, environmentally friendly and sustainable treatment technology for the treatment of wastewater. Hence, a wide band gap Ta2O5 semiconductor nanoparticle was prepared by the hydrothermal method and considerable efforts have been taken to narrow the band gap, i.e., the surface modification has been done with a noble metal (Au0) by a deposition precipitation method. As synthesized, Au–Ta2O5 semiconductor was well characterized by X-ray diffraction (XRD), X-ray photo electron spectroscopy (XPS), transmission electron microscopy (TEM) and diffused reflectance UV-vis spectroscopy (DRS). The photocatalytic potential of Au–Ta2O5 semiconductor was investigated by degrading Methyl Orange in the presence and absence of electron acceptors by illuminating with visible light of intensity 80 600 ± 10 Lux.

Sonochemical synthesis and characterization of turbostratic MnNi(OH)2 layered double hydroxide nanoparticles for supercapacitor applications

In this research, manganese and nickel transition metal layered double hydroxide nanoparticles (MnNi(OH)2) with a size of ∼100 nm have been successfully prepared using a sonochemical irradiation method for supercapacitor applications. X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) analyses clearly indicate the formation of MnNi(OH)2 nanoparticles. Scanning and Transmission electron microscopic images identify the layered double hydroxide structure formation. MnNi(OH)2 layered double hydroxide nanoparticles were tested as a supercapacitor material which exhibits specific capacitance of 160 F g−1 at a current density of 1 mA cm−2 at the potential range from 0.0 to 1.0 V in 1 M Na2SO4 solution.

SnO2-decorated multiwalled carbon nanotubes and Vulcan carbon through a sonochemical approach for supercapacitor applications

Multiwalled carbon nanotubes (MWCNTs) and Vulcan carbon (VC) decorated with SnO2 nanoparticles were synthesized using a facile and versatile sonochemical procedure. The as-prepared nanocomposites were characterized by means of transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infra red spectroscopy. It was evidenced that SnO2 nanoparticles were uniformly distributed on both carbon surfaces, tightly decorating the MWCNTs and VC. The electrochemical performance of the nanocomposites was evaluated by cyclic voltammetry and galvanostatic charge/discharge cycling. The as-synthesized SnO2/MWCNTs nanocomposites show a higher capacity than the SnO2/VC nanocomposites. Concretely, the SnO2/MWCNTs electrodes exhibit a specific capacitance of 133.33 F g(-1), whereas SnO2/VC electrodes exhibit a specific capacitance of 112.14 F g(-1) measured at 0.5 mA cm(-2) in 1 M Na2SO4.

Catalytic Ozonation of Oxalic Acid Using SrTiO3 Catalyst

A new catalyst, strontium titanate (SrTiO3), has been successfully employed to degrade oxalic acid in catalytic ozonation process. About 4.5%, 9.3% and 45.8% of oxalic acid removal efficiencies were noted in adsorption, ozonation, and catalytic ozonation processes, respectively, which demonstrates the catalytic activity of SrTiO3 towards ozone. The optimum amount of catalyst loading on decomposing oxalic acid was found to be 1.25 g/L. The catalytic stability was investigated up to four successive cycles and found that the catalyst was still stable and efficient.

Effect of floc strength on sludge dewatering by vacuum filtration

Abstract In this paper, the floc strength requirement of the alum sludge was experimentally investigated for its application on vacuum filtration. Floc strength analysis confirmed that the addition of polymer enforced the floc strength substantially, even in over-dosage, and, therefore, reduced the floc breakage of the alum sludge. The improvement in dewaterability and the minimum floc breakage suggested that floc strength of 5.5 is the optimal condition for vacuum filtration of slum sludge. A diagram is also conducted to demonstrate the application of floc strength depending upon shear stress of the dewatering by vacuum filtration.

Catalytic oxidation of phenol in the presence of iron-containing composites based on silicon and boron nitrides

Sorption and catalytic activities of iron-containing composites based on silicon and boron nitrides in purification of aqueous solutions to remove phenol under ozonation and UV irradiation in the presence of oxalic acid and hydrogen peroxide additives was studied.

Sensitive electrochemical determination of dopamine and uric acid using AuNPs(EDAS)–rGO nanocomposites

Here we report, the ultrasonication-assisted and N-[3(trimethoxysilyl)propyl]ethylenediamine] (EDAS) in the aqueous phase mediated the reduction of hydrogen tetrachloroaurate(III) trihydrate (HAuCl4·3H2O) and graphene oxide (GO) by a facile and environmentally benign “single-step one-pot approach”. EDAS, a kind of aliphatic amine, was utilized as a capping and stabilizing agent to prevent the aggregation of AuNPs in aqueous medium as well as functionalization of reduced graphene oxide (rGO). FTIR spectroscopy was used to examine the probable complexation mechanism occurring between Au ions and EDAS and their subsequent reduction to AuNPs on the surface of rGO. The size of AuNPs that formed on the surface of rGO was in the range of ∼5–8 nm. In the X-ray diffraction, the (111), (200), and (220) facets of AuNPs(EDAS) were observed along with the (002) plane of rGO. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and amperometric (i–t) experiments were performed to characterize the prepared AuNPs(EDAS)–rGO nanocomposites utilized as an electrochemical sensor for the simultaneous detection of dopamine (DA) and uric acid (UA). In DPV, the peak separation between dopamine (DA) and uric acid (UA) was large up to 0.25 V. The calibration curves of DA and UA were obtained in the ranges of 0.05–11 μM and 0.1–11 μM with detection limits (S/N = 3) of 0.02 μM and 0.03 μM, respectively. Furthermore, this modified electrode was further applied to determine DA and UA in real samples with satisfactory results.