Assisted sonocatalytic degradation of pethidine hydrochloride (dolantin) with some inorganic oxidants caused by CdS-coated ZrO2 composite

Ultrasensitive functionalized CeO2/ZnO nanocomposite sensor for determination of a prohibited narcotic in sports pethidine hydrochloride

The extraordinary features of cerium oxide (CeO₂) and zinc oxide (ZnO) nanostructures have encouraged substantial attention to those nanocomposites as probable electroactive complexes for sensing and biosensing purposes. In this study, an advanced novel factionalized CeO₂/ZnO nanocomposite-aluminum wire membrane sensor was designed to assess pethidine hydrochloride (PTD) in commercial injection samples. Pethidine-reineckate (PTD-RK) was formed by mixing pethidine hydrochloride and ammonium reineckate (ARK) in the presence of polymeric matrix (polyvinyl chloride) and o-nitrophenyl octyl ether as a fluidizing agent. The functionalized nanocomposite sensor displayed a fast dynamic response and wide linearity for the detection of PTD. It also revealed excellent selectivity and sensitivity, high accuracy, and precision for the determination and quantification of PTD when compared with the unmodified sensor PTD-RK. The guidelines of analytical methodology requirements were obeyed to improve the suitability and validity of the suggested potentiometric system according to several criteria. The developed potentiometric system was suitable for the determination of PTD in bulk powder and commercial products.

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.

Hybrid Advanced Oxidation Processes Involving Ultrasound: An Overview

Sonochemical oxidation of organic pollutants in an aqueous environment is considered to be a green process. This mode of degradation of organic pollutants in an aqueous environment is considered to render reputable outcomes in terms of minimal chemical utilization and no need of extreme physical conditions. Indiscriminate discharge of toxic organic pollutants in an aqueous environment by anthropogenic activities has posed major health implications for both human and aquatic lives. Hence, numerous research endeavours are in progress to improve the efficiency of degradation and mineralization of organic contaminants. Being an extensively used advanced oxidation process, ultrasonic irradiation can be utilized for complete mineralization of persistent organic pollutants by coupling/integrating it with homogeneous and heterogeneous photocatalytic processes. In this regard, scientists have reported on sonophotocatalysis as an effective strategy towards the degradation of many toxic environmental pollutants. The combined effect of sonolysis and photocatalysis has been proved to enhance the production of high reactive-free radicals in aqueous medium which aid in the complete mineralization of organic pollutants. In this manuscript, we provide an overview on the ultrasound-based hybrid technologies for the degradation of organic pollutants in an aqueous environment.

Construction of coated Z-scheme Pd-BaZrO3@WO3 composite with enhanced sonocatalytic activity for diazinon degradation in aqueous solution

The coated Z-scheme Pd-BaZrO₃@WO₃ composite as a new-type sonocatalyst with highly sonocatalytic performance is first constructed through sol-gel and hydro-thermal synthesis methods. The chemical configuration, structure and component are characterized by a series of characterization methods. The sonocatalytic degradation of diazinon as a model pollutant is studied to estimate the sonocatalytic performance of coated Z-scheme Pd-BaZrO₃@WO₃ composite. Some affecting factors such as Pd-BaZrO₃ and WO₃ mass proportions, ultrasonic (US) irradiation time, reusability and catalyst dosage are researched in detail through UV-vis spectra and gas chromatography (GC). The produced intermediates are detected in the degradation process of diazinon by using gas chromatography-mass spectrometer (GC-MS). The possible reaction mechanism of coated Z-scheme Pd-BaZrO₃@WO₃ sonocatalyst in sonocatalytic degradation process is also explored. Subsequently, the hydroxyl radicals (OH) and holes (h⁺) are discriminated to further elaborate the possible sonocatalytic mechanism. The experimental results manifest that the coated Z-scheme Pd-BaZrO₃@WO₃ sonocatalyst displays a preeminent sonocatalytic performance under ultrasonic irradiation because it can efficaciously suppress recombination of electrons (e^-) and holes (h⁺), extend light response scope and provide almost 100% oxidization surface. In addition, the introduced palladium (Pd) nanorods connecting BaZrO₃ and WO₃ can expedite e^- transfer. Under optimal conditions, the most of diazinon molecules can be disintegrated in the existence of the coated Z-scheme Pd-BaZrO₃@WO₃ under ultrasonic irradiation for 150 min. This study provides a feasible method for the treatment of environmental pollutions.

A comprehensive study on the photocatalytic activity of coupled copper oxide-cadmium sulfide nanoparticles

Coupled CdS-CuO nanoparticles (NPs) subjected in the photocatalytic degradation of Methylene blue (MB) aqueous solution. The calcination temperature and the crystallite phase of CuO had a significant role on the photocatalytic activity of the coupled system and CuO_200/2h-CdS catalyst (containing CuO calcined at 200°C for 2h) showed the best photocatalytic activity. The coupled system showed increased activity with respect to the monocomponent semiconductors. The prepared catalysts characterized by x-ray diffraction (XRD), scanning electron microscope equipped with energy dispersive X-ray (EDX) analyzer, x-ray mapping, Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance spectroscopy (DRS) and electrochemical impedance spectroscopy (EIS) techniques. The best degradation extent of MB was obtained at: C_MB: 1mgL^-1, pH5, 80min irradiation time and 0.8gL^-1 of the CuO_200/2h-CdS catalyst. The chemical oxygen demand (COD) confirmed about 83% of MB molecules can be mineralized at the optimum conditions.

Sonocatalytic degradation of rhodamine B in presence of CdS

A novel sonocatalyst CdS was prepared by a facile precipitation method, and characterized by X-ray powder diffraction, transmission electron microscopy, UV-vis absorption spectroscopy, and photoluminescence spectroscopy. Comparative sonocatalytic degradation experiments were carried out in different conditions under ultrasonic irradiation and with rhodamine B (RhB) used as the model substrate. Results indicate that CdS is a highly active sonocatalyst. The efficiency of RhB sonodegradation in aqueous solutions within 4 h is up to 70% after the addition of CdS. Abundant •OH during the RhB sonodegradation was detected, which may be responsible for the high sonodegradation rate over CdS under ultrasonic radiation.

Preparation of Ce4+-doped BaZrO3 by hydrothermal method and application in dual-frequent sonocatalytic degradation of norfloxacin in aqueous solution

In this paper, the dual-frequent sonocatalytic degradation of norfloxacin (NOR), an antibiotic, caused by Ce⁴⁺-doped BaZrO₃ is studied. The used Ce⁴⁺-doped BaZrO₃ as a novel sonocatalyst with highly efficient and stable sonocatalytic activity is prepared via hydrothermal method. The prepared sample is characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (DRS) and Fourier transform infrared spectra (FT-IR) in order to investigate the structure, morphology and chemical composition. The dual-frequent sonocatalytic activity of prepared Ce⁴⁺-doped BaZrO₃ powder is evaluated through sonocatalytic degradation of norfloxacin (NOR) as a model organic pollutant. Some influencing factors such as single/dual-frequent ultrasonic frequent, cerium and zirconium molar proportions, ultrasonic irradiation time and used times are studied in detail by using UV-vis spectra. The generated reactive oxygen species (ROS) during the dual-frequent sonocatalytic degradation process of norfloxacin (NOR) are confirmed by using two different trapping agents. The holes (h⁺) and hydroxyl radicals (OH) are identified and the holes plays a major role during the oxidation process. Finally, the possible mechanism for the dual-frequent sonocatalytic degradation of norfloxacin (NOR) caused by Ce⁴⁺-doped BaZrO₃ is proposed. The experimental results show that the Ce⁴⁺-doped BaZrO₃ displays a good sonocatalytic activity under dual-frequent ultrasonic irradiation. Under optimal conditions, the most of norfloxacin (NOR) can be removed under dual-frequent ultrasonic irradiation for 150 min.

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 60min, 11, 50mg/L, 1.00g/L, and 40W/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 asa novel-design catalyst for the removal of organic pollutants from aqueous solutions.

Sonocatalytic degradation of Reactive Yellow 39 using synthesized ZrO2 nanoparticles on biochar

ZrO₂-biochar (ZrO₂-BC) nanocomposite was prepared by a modified sonochemical/sol-gel method. The physicochemical properties of the prepared nanocomposite were evaluated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray fluorescence, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller model. The sonocatalytic performance of ZrO₂-BC was investigated in sonochemical degradation of Reactive Yellow 39 (RY39). The high observed sonocatalytic activity of the ZrO₂-BC sample could be interpreted by the mechanisms of sonoluminescence and hot spots. Parameters including ZrO₂-BC dosage, solution pH, initial RY39 concentration and ultrasonic power were selected as the main operational parameters and their influence on RY39 degradation efficiency was examined. A 96.8% degradation efficiency was achieved with a ZrO₂-BC dosage of 1.5g/L, pH of 6, initial RY39 concentration of 20mg/L and ultrasonic power of 300W. In the presence of OH radical scavengers, RY39 degradation was significantly inhibited, providing evidence for the key role of hydroxyl radicals in the process. The sonodegradation intermediates were identified using gas chromatography-mass spectroscopy and the possible decomposition route was proposed.

Aqueous norfloxacin sonocatalytic degradation with multilayer flower-like ZnO in the presence of peroxydisulfate

Multilayer ZnO nanoflowers were synthesized through a simple precipitation method and characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) and nitrogen absorption-desorption techniques. The FE-SEM images show the integrated morphology of an individual flower-like ZnO nanostructure, which is made of nano-platelets with uniform thickness (20-30nm). The average pore size and Brunauer-Emmet-Teller (BET) surface area of the as-synthesized ZnO were 27.25nm and 13.53m²/g. The sonocatalytic ability of the prepared samples was evaluated through norfloxacin (NF) degradation in an aqueous system using ultrasound (US) irradiation. To improve degradation efficiency, peroxydisulfate (Na₂S₂O₈) was introduced to develop a US/ZnO/peroxydisulfate system, which exhibited an excellent synergistic effect. The effects of ZnO dosage, Na₂S₂O₈ concentration, pH, and initial NF concentration were studied to determine the performances of the US/ZnO/peroxydisulfate process. Corresponding results showed that NF degradation rate increased with the increase of ZnO dosage but decreased with the increase of initial NF concentration. Under the optimal Na₂S₂O₈ concentration of 0.1gL^-1 at pH 9, the best degradation efficiency can be achieved. Moreover, based on the scavenging experiment results and literatures, NF degradation through US/ZnO/peroxydisulfate system is majorly induced by OH and SO₄^- radicals.

Hydrothermal-precipitation preparation of CdS@(Er3+:Y3Al5O12/ZrO2) coated composite and sonocatalytic degradation of caffeine

Here, we reported a novel method to dispose caffeine by means of ultrasound irradiation combinated with CdS@(Er³⁺:Y₃Al₅O₁₂/ZrO₂) coated composite as sonocatalyst. The CdS@(Er³⁺:Y₃Al₅O₁₂/ZrO₂) was synthesized via hydrothermal-precipitation method and then characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and UV-vis diffuse reflectance spectra (DRS). After that, the sonocatalytic degradation of caffeine in aqueous solution was conducted adopting CdS@(Er³⁺:Y₃Al₅O₁₂/ZrO₂) and CdS@ZrO₂ coated composites as sonocatalysts. In addition, some influencing factors such as CdS and ZrO₂ molar proportion, caffeine concentration, ultrasonic irradiation time, sonocatalyst dosage and addition of several inorganic oxidants on sonocatalytic degradation of caffeine were investigated by using UV-vis spectra and gas chromatograph. The experimental results showed that the presence of Er³⁺:Y₃Al₅O₁₂ could effectively improve the sonocatalytic degradation activity of CdS@ZrO₂. To a certain extent some inorganic oxidants can also enhance sonocatalytic degradation of caffeine in the presence of CdS@(Er³⁺:Y₃Al₅O₁₂/ZrO₂). The best sonocatalytic degradation ratio (94.00%) of caffeine could be obtained when the conditions of 5.00mg/L caffeine, 1.00g/L prepared CdS@(Er³⁺:Y₃Al₅O₁₂/ZrO₂), 10.00mmol/LK₂S₂O₈, 180min ultrasonic irradiation (40kHz frequency and 50W output power), 100mL total volume and 25-28°C temperature were adopted. It seems that the method of sonocatalytic degradation caused by CdS@(Er³⁺:Y₃Al₅O₁₂/ZrO₂) displayspotentialadvantages in disposing caffeine.

Fabrication of nanoporous copper with tunable ligaments and promising sonocatalytic performance by dealloying Cu–Y metallic glasses

Nanoporous copper (NPC) with tunable ligaments was prepared by dealloying new Cu–Y binary metallic glasses. The sono-Fenton-like process of NPC with desired microstructure shows great potential in degrading organic dyes.