Sonochemical activation-assisted biosynthesis of Au/Fe3O4 nanoparticles and sonocatalytic degradation of methyl orange

In this research, a sonochemical activation-assisted biosynthesis of Au/Fe₃O₄ nanoparticles is proposed. The proposed synthesis methodology incorporates the use of Piper auritum (an endemic plant) as reducing agent and in a complementary way, an ultrasonication process to promote the synthesis of the plasmonic/magnetic nanoparticles (Au/Fe₃O₄). The synergic effect of the green and sonochemical synthesis favors the well-dispersion of precursor salts and the subsequent growth of the Au/Fe₃O₄ nanoparticles.The hybrid green/sonochemical process generates an economical, ecological and simplified alternative to synthesizing Au/Fe₃O₄ nanoparticles whit enhanced catalytic activity, pronounced magnetic properties. The morphological, chemical and structural characterization was carried out by high- resolution Scanning electron microscopy (HR-SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and X-Ray diffraction (XRD), respectively. Ultraviolet–visible (UV–vis) and X-ray photoelectron (XPS) spectroscopy confirm the Au/Fe₃O₄ nanoparticles obtention. The magnetic properties were evaluated by a vibrating sample magnetometer (VSM). Superparamagnetic behavior, of the Au/ Fe₃O₄ nanoparticles was observed (M_s = 51 emu/g and H_c = 30 Oe at 300 K). Finally, the catalytic activity was evaluated by sonocatalytic degradation of methyl orange (MO). In this stage, it was possible to achieve a removal percentage of 91.2% at 15 min of the sonocatalytic process (160 W/42 kHz). The initial concentration of the MO was 20 mg L⁻¹, and the Fe3O4-Au dosage was 0.075 gL⁻¹. The MO degradation process was described mathematically by four kinetic adsorption models: Pseudo-first order model, Pseudo-second order model, Elovich and intraparticle diffusion model.     

Sonochemical synthesis, photocatalytic activity and optical properties of silica coated ZnO nanoparticles

In this paper, we report the synthesis of silica coated ZnO nanoparticles by ultrasound irradiation of a mixture of dispersion of ZnO, tetraethoxysilane (TEOS), and ammonia in an ethanol-water solution medium. The silica coating layer formed at the initial TEOS/ZnO loading of 0.8 for 60 min ultrasonic irradiation was uniform and extended up to 3 nm from the ZnO surface as revealed from HR-TEM images. Silica coated ZnO nanoparticles demonstrated a significant inhibition of photocatalytic activity against photodegradation of methylene blue dye in aqueous solution. The effects of silica coating on the UV blocking property of ZnO nanoparticles were also studied.     

Ultrasonic-assisted degradation of phenazopyridine with a combination of Sm-doped ZnO nanoparticles and inorganic oxidants

Pure and samarium doped ZnO nanoparticles were synthesized by a sonochemical method and characterized by TEM, SEM, EDX, XRD, Pl, and DRS techniques. The average crystallite size of pure and Sm-doped ZnO nanoparticles was about 20 nm. The sonocatalytic activity of pure and Sm-doped ZnO nanoparticles was considered toward degradation of phenazopyridine as a model organic contaminant. The Sm-doped ZnO nanoparticles with Sm concentration of 0.4 mol% indicated a higher sonocatalytic activity (59%) than the pure ZnO (51%) and other Sm-doped ZnO nanoparticles. It was believed that Sm³⁺ ion with optimal concentration (0.4 mol%) can act as superficial trapping for electrons in the conduction band of ZnO and delayed the recombination of charge carriers. The influence of the nature and concentration of various oxidants, including periodate, hydrogen peroxide, peroxymonosulfate, and peroxydisulfate on the sonocatalytic activity of Sm-doped ZnO nanoparticles was studied. The influence of the oxidants concentration (0.2–1.4 g L⁻¹) on the degradation rate was established by the 3D response surface and the 2D contour plots. The results demonstrated that the utilizing of oxidants in combination with Sm-doped ZnO resulting in rapid removal of contaminant, which can be referable to a dual role of oxidants; (i) scavenging the generated electrons in the conduction band of ZnO and (ii) creating highly reactive radical species under ultrasonic irradiation. It was found that the Sm-doped ZnO and periodate combination is the most efficient catalytic system under ultrasonic irradiation.     

Sonocatalytic degradation of a textile dye over Gd-doped ZnO nanoparticles synthesized through sonochemical process

The present study was performed to sonochemically synthesize Gd_xZn_1 − xO (x = 0–0.1) nanoparticles for sonocatalysis of Acid Orange 7 (AO7) in an aqueous medium. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis confirmed proper synthesis of Gd-doped sonocatalyst. 5% Gd-doped ZnO nanoparticles with band gap of 2.8 eV exhibited the highest sonocatalytic decolorization efficiency of 90% at reaction time of 90 min. The effects of initial dye concentration and sonocatalyst dosage on decolorization efficiency were evaluated. In the presence of sodium sulfate, sodium carbonate and sodium chloride the decolorization efficiency decreased from 90 to 78, 65 and 56%, respectively. Among various enhancers, the addition of potassium periodate improved the decolorization efficiency from 90 to 100%. The highest decolorization efficiency was obtained at pH value of 6.34 (90%). The decolorization efficiency decreased only 6% after 4 repeated runs. Therefore, Gd-doped ZnO nanoparticles can be used as a promising catalyst for degradation of organic pollutants with great reusability potential.     

Sonochemical synthesis of carbon supported Sn nanoparticles and its electrochemical application

A sonochemical approach was employed to prepare Vulcan carbon XC-72R supported by Sn nanoparticles at room temperature in the presence of ethylene glycol. The reduction of metallic Sn ion and ethylene glycol takes place and in turn the glycolate ion as formed acts as a stabilizing agent. Transmission electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy have illustrated that the metallic Sn nanoparticles are successfully embedded on the carbon. The significantly observed reduction over potential for oxygen reduction reaction displays a higher catalytic activity of carbon supported by Sn nanoparticles due to the large surface area of the modified electrode.     

Sonochemical synthesis of versatile hydrophilic magnetite nanoparticles

Hydrophilic magnetite nanoparticles in the size range 30-10 nm are easily and rapidly prepared under ultrasonic irradiation of Fe(OH)₂ in di- and tri-ethylene glycol/water solution with volume ratio varying between 7:3 and 3:7.Structural (XRD) and morphological (SEM) characterization reveal good crystalline and homogeneous particles whereas, when solvothermally prepared, the particles are inhomogeneous and aggregated. The sonochemically prepared particles are versatile, i.e. well suited to covalently bind molecules because of the free glycol hydroxylic groups on their surface or exchange the diethylene or triethylene glycol ligand. They can be easily transferred in hydrophobic solvents too.Room-temperature magnetic hysteresis properties measured by means of Vibrating Sample Magnetometer (VSM) display a nearly superparamagnetic character.The sonochemical preparation is easily scalable to meet industrial demand.     

Growth mechanism and optical property of ZnO nanoparticles synthesized by sonochemical method

ZnO nanoparticles have been synthesized by ultrasonic irradiation of an aqueous-alcoholic/aqueous-alcoholic-ethylenediamine (EDA) solutions of zinc nitrate and sodium hydroxide. ZnO nanoparticles possess hexagonal wurtzite structures and they exhibit special photoluminescence properties with a red-shift of 22 nm in UV emission band. It is found that the ultrasonic irradiation time and the solvents both influence the growth mechanism and optical properties of ZnO nanoparticles. The possible growth mechanism of ZnO nanoparticles formation by sonochemical method has been tried to discuss.     

Two-step synthesis and characterization of ZnO nanoparticles

A novel two-step procedure has been employed for the synthesis of ZnO nanoparticles: (1) mechanochemical synthesis of ZnC₂O₄2H₂O nanoparticles by grinding a mixture of zinc acetate and oxalic acid in an agate mortar at 27 °C and (2) thermal decomposition of ZnC₂O₄2H₂O nanoparticles at 400 °C to form ZnO nanoparticles. XRD and FESEM characterize the final product as highly crystalline ZnO with wurtzite structure and crystallite sizes in the range 5–20 nm. FTIR and EPR are used to identify molecular species during thermal decomposition and impurity/defect status of the ZnO powder respectively.     

Template-free sonochemical synthesis of flower-like ZnO nanostructures

Flower-like ZnO nanostructures have been successfully synthesized via a facile and template-free sonochemical method, using zinc acetate and potassium hydroxide as reactants only. The as-synthesized flower-like ZnO nanostructures were composed of nanorods with the width of ∼300–400 nm$\sim 300\text{–}400\text{nm}$ and the length of ∼2–3 μm$\sim 2\text{–}3\text{μm}$. The structures, morphologies and optical properties of the as-prepared products were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscopy, UV-Vis spectrophotometry and Raman-scattering spectroscopy. A plausible formation mechanism of flower-like ZnO nanostructures was studied by SEM which monitors an intermediate morphology transformation of the product at the different ultrasonic time (t=80,90,95,105, and 120 min$t=80,90,95,105\text{, and}120\text{min}$).     

Sonochemical assisted synthesis of SrFe12O19 nanoparticles

We present the synthesis of M-type strontium hexaferrite by sonochemistry and annealing. The effects of the sonication time and thermal energy on the crystal structure and magnetic properties of the obtained powders are presented. Strontium hexagonal ferrite (SrFe₁₂O₁₉) was successfully prepared by the ultrasonic cavitation (sonochemistry) of a complexed polyol solution of metallic acetates and diethylene glycol. The obtained materials were subsequently annealed at temperatures from 300 to 900 °C. X-ray diffraction analysis shows that the sonochemical process yields an amorphous phase containing Fe³⁺, Fe²⁺ and Sr²⁺ ions. This amorphous phase transforms into an intermediate phase of maghemite (γ-Fe₂O₃) at 300 °C. At 500 °C, the intermediate species is converted to hematite (α-Fe₂O₃) by a topotactic transition. The final product of strontium hexaferrite (SrFe₁₂O₁₉) is generated at 800 °C. The obtained strontium hexaferrite shows a magnetization of 62.3 emu/g, which is consistent with pure hexaferrite obtained by other methods, and a coercivity of 6.25 kOe, which is higher than expected for this hexaferrite. The powder morphology is composed of aggregates of rounded particles with an average particle size of 60 nm.     

Sonochemical synthesis,structural, magnetic and grain size dependent electrical properties of NdVO4 nanoparticles

NdVO₄ nanoparticles are successfully synthesized by efficient sonochemical method using two different structural directing agents like CTAB and P123. The phase formation and functional group analysis are carried out using X-ray diffraction (XRD) and fourier transform infra red (FT-IR) spectra, respectively. Using Scherrer equation the calculated grain sizes are 27 nm, 24 nm and 20 nm corresponding to NdVO₄ synthesized by without surfactant, with CTAB and P123, respectively. The TEM images revealed that the shape of NdVO₄ particles is rice-like and rod shaped particles while using CTAB and P123 as surfactants. The growth mechanism of NdVO₄ nanoparticles is elucidated with the aid of TEM analysis. From electrical analysis, the conductivity of NdVO₄ nanoparticles synthesized without surfactant showed a higher conductivity of 5.5703 × 10⁻⁶ S cm⁻¹. The conductivity of the material depends on grain size and increased with increase in grain size due to the grain size effect. The magnetic measurements indicated the paramagnetic behavior of NdVO₄ nanoparticles.     

Room temperature synthesis of needle-shaped ZnO nanorods via sonochemical method

Single crystalline needle-shaped zinc oxide nanorods were synthesized via sonochemical methods using zinc acetate dihydrate and sodium hydroxide at room temperature. Morphological investigation revealed that the nanoneedles are of hexagonal surfaces along the length. The typical diameter and length vary from 120 to 160 nm and 3 to 5 μm, respectively. Sonication time appears to be a critical parameter for the shape determination. Detailed structural characterization confirmed that the nanorods are single crystalline with wurtzite hexagonal phase. A standard peak of zinc oxide was observed at 520 cm⁻¹ from the Fourier transform infrared spectroscopy. The ultra-violet visible and room temperature photoluminescence (PL) spectroscopic results demonstrate that the synthesized material has good optical properties.     

Preparation of cube micrometer potassium niobate (KNbO3) by hydrothermal method and sonocatalytic degradation of organic dye

Cube micrometer potassium niobate (KNbO₃) powder, as a high effective sonocatalyst, was prepared using hydrothermal method, and then, was characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). In order to evaluate the sonocatalytic activity of prepared KNbO₃ powder, the sonocatalytic degradation of some organic dyes was studied. In addition, some influencing factors such as heat-treatment temperature and heat-treatment time on the sonocatalytic activity of prepared KNbO₃ powder and catalyst added amount and ultrasonic irradiation time on the sonocatalytic degradation efficiency were examined by using UV–visible spectrophotometer and Total Organic Carbon (TOC) determination. The experimental results showed that the best sonocatalytic degradation ratio (69.23%) of organic dyes could be obtained when the conditions of 5.00 mg/L initial concentration, 1.00 g/L prepared KNbO₃ powder (heat-treated at 400 °C for 60 min) added amount, 5.00 h ultrasonic irradiation (40 kHz frequency and 300 W output power), 100 mL total volume and 25–28 °C temperature were adopted. Therefore, the micrometer KNbO₃ powder could be considered as an effective sonocatalyst for treating non- or low-transparent organic wastewaters.     

Enhanced sonocatalytic degradation of organic dyes from aqueous solutions by novel synthesis of mesoporous Fe3O4-graphene/ZnO@SiO2 nanocomposites

Fe₃O₄-graphene/ZnO@mesoporous-SiO₂ (MGZ@SiO₂) nanocomposites was synthesized via a simple one pot hydrothermal method. The as-obtained samples were investigated using various techniques, as follows: scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and specific surface area (BET) vibrating sample magnetometer (VSM), among others. The sonocatalytic activities of the catalysts were tested according to the oxidation for the removal of methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) under ultrasonic irradiation. The optimal conditions including the irradiation time, pH, dye concentration, catalyst dosage, and ultrasonic intensity are 60 min, 11, 50 mg/L, 1.00 g/L, and 40 W/m², respectively. The MGZ@SiO₂ showed the higher enhanced sonocatalytic degradation from among the three dyes; furthermore, the sonocatalytic-degradation mechanism is discussed. This study shows that the MGZ@SiO₂ can be applied as a novel-design catalyst for the removal of organic pollutants from aqueous solutions.     

超声化学法制备纳米WO3掺杂聚苯乙烯及其表征

 为了满足惯性约束聚变和电磁内爆实验对靶材料的需求，以W(CO)_{5/sub>为原料，利用超声化学法在线制备纳米WO3/sub>掺杂聚苯乙烯。所得样品用TEM，XPS，FTIR和TG进行了表征。测试结果表明，钨元素主要以WO3/sub>的形态存在，WO3/sub>粒径分布为20~50 nm，WO3/sub>微粒被聚苯乙烯完全包覆，掺杂后聚苯乙烯的热稳定性提高了70 ℃。在此基础上，对超声化学法的反应机理进行了探讨。研究表明：纳米WO3/sub>与聚苯乙烯分子链有一定的化学键结合，纳米WO3/sub>在聚苯乙烯基体中分布均匀。}     

Sonochemical and visible light induced photochemical and sonophotochemical degradation of dyes catalyzed by recoverable vanadium-containing polyphosphomolybdate immobilized on TiO2 nanoparticles

Na₅PV₂Mo₁₀O₄₀ supported on nanoporous anatase TiO₂ particles, TiO₂–PVMo, was used as an efficient photocatalyst for photocatalytic degradation of different dyes by visible light using oxygen as oxidant. This catalyst showed a good catalytic activity in the sonocatalytic and sonophotocatalytic decomposition of different dyes in aqueous solutions. The TiO₂–PVMo composite showed higher photocatalytic and sonocatalytic activity than pure polyoxometalate or pure TiO₂.     

Sonochemical synthesis,characterization and application of PrVO4 nanostructures as an effective photocatalyst for discoloration of organic dye contaminants in wastewater

In the current research, various conventional chemical preparation methods without ultrasound aid (precipitation, microwave, and hydrothermal) were compared with sonochemical procedure and were performed for providing of PrVO₄ nanostructures using Schiff-base ligands. The small size products with monodisperse particles (~39 nm) optimized by sonochemical fabrication method and using H₂ acacpn ligand via ultrasonic probe with power of 60 W and frequency of 18 KHz. The produced PrVO₄ nanostructures applied for degradation of diverse organic dyes through the photocatalytic process. Dye types, pH adjusting of dye, dosage of catalyst, synthesis method of nanoparticles and light source as impressive factors inquired for dye removal ability. The outcomes presented the removal efficiency of Eriochorom Black T in optimal conditions of pH = 11 and the catalysts amounts of PrVO₄ were adjusted to be 0.05 g. The PrVO₄ photocatalyst shows high removal efficiency (ca 86.92 and 89.61%) after 90 min of operation under UV light. The best-obtained framework confirmed the basic study to compare different method in order to acquire suitable catalyst materials. The simple, fast and economic strategy for synthesis PrVO₄ with high photodegradation efficiency is sonochemical method against other ways, and it could be extended to the most efficient catalyst materials for water treatment. Consequently, the PrVO₄ may suggestion a hopeful avenue for designing the novel generation, low-cost and outstanding potential photocatalyst materials for water treatment.     

Piezo/sono-catalytic activity of ZnO micro/nanoparticles for ROS generation as function of ultrasound frequencies and dissolved gases

We report an accurate study on sonocatalytic properties of different ZnO micro and nanoparticles to enhance OH radical production activated by cavitation. In order to investigate some of the still unsolved aspects related to the piezocatalytic effect, the degradation of Methylene Blue and quantification of radicals production have been evaluated as function of different ultrasonic frequencies (20 kHz and 858 kHz) and dissolved gases (Ar, N₂ and air). The results shown that at low frequency the catalytic effect of ZnO particles is well evident and influenced by particle dimension while at high frequency a reduction of the degradation efficiency have been observed using larger particles. An increase of radical production have been observed for all ZnO particles tested while the different saturating gases have poor influence. In both ultrasonic set-up the ZnO nanoparticles resulted the most efficient on MB degradation revealing that the enhanced radical production may arise more from bubbles collapse on particles surface than the discharge mechanism activate by mechanical stress on piezoelectric particles. An interpretation of these effects and a possible mechanism which rules the sonocatalytic activity of ZnO will be proposed and discussed.     

Sonochemical synthesis and characterization of three nano zinc(II) coordination polymers; Precursors for preparation of zinc(II) oxide nanoparticles

Nanostructures of three Zinc(II) coordination polymers, [Zn(NNO)₂(H₂O)₄]_n (1), [Zn(PNNO)₂(H₂O)₂]_n (2) and [Zn(H₂O)₆]·(INNO)₂ (3) {NNO: Nicotinic acid N-oxide, PNNO: Picolinic acid N-oxide and INNO: Isonicotinic acid N-oxide}, have been synthesized by a sonochemical process and reaction of ligands with Zn(CH₃COO)₂. The Zinc(II) oxide nano-particles have been synthesized from thermolysis of [Zn(NNO)₂(H₂O)₄]_n (1), [Zn(PNNO)₂(H₂O)₂]_n (2) and [Zn(H₂O)₆]·(INNO)₂ (3) at two different methods (with surfactant and without surfactant) and two temperatures (200 and 600 °C). The ZnO nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Comparison of the SEM images of ZnO nano-particles at two different methods and temperatures shows that higher temperature results in an increasing of agglomeration and thus small and spherical ZnO particles with good separation were produced by thermolysis of compounds at 200 °C and by use of surfactant.     

Sonochemical assisted hydrothermal synthesis of ZnO: Cr nanoparticles loaded activated carbon for simultaneous ultrasound-assisted adsorption of ternary toxic organic dye: Derivative spectrophotometric,optimization, kinetic and isotherm study

Chromium doped zinc oxide nanoparticles (ZnO: Cr-NPs) was synthesized by ultrasonically assisted hydrothermal method and characterized by FE-SEM, XRD and TEM analysis. Subsequently, this composite ultrasonically assisted was deposited on activated carbon (ZnO: Cr-NPs-AC) and used for simultaneous ultrasound-assisted removal of three toxic organic dye namely of malachite green (MG), eosin yellow (EY) and Auramine O (AO). Dyes spectra overlap in mixture (major problem for simultaneous investigation) of this systems was extensively resolved by derivative spectrophotometric method. The magnitude of variables like initial dyes concentration, adsorbent mass and sonication time influence on dyes removal was optimized using small central composite design (CCD) combined with desirability function (DF) approach, while pH was studied by one-a-time approach. The maximized removal percentages at desirability of 0.9740 was set as follow: pH 6.0, 0.019 g ZnO: Cr-NPs-AC, 3.9 min sonication at 4.5, 4.8 and 4.7 mg L⁻¹ of MG, EY and AO, respectively. Above optimized points lead to achievement of removal percentage of 98.36%, 97.24%, and 99.26% correspond to MG, EY and AO, respectively. ANOVA for each dyes based p-value less than (<0.0001) suggest highly efficiency of CCD model for prediction of data concern to simultaneous removal of these dyes within 95% confidence interval, while their F-value for MG, EY and AO is 935, 800.2, and 551.3, respectively, that confirm low participation of this them in signal. The value of multiple correlation coefficient R², adjusted and predicted R² for simultaneous removal of MG is 0.9982, 0.9972 and 0.9940, EY is 0.9979, 0.9967 and 0.9930 and for AO is 0.9970, 0.9952 and 0.9939. The adsorption rate well fitted by pseudo second-order and Langmuir model via high, economic and profitable adsorption capacity of 214.0, 189.7 and 211.6 mg g⁻¹ for MG, EY and AO, respectively.