Sonocatalytic Degradation Research Articles

Improvement of Ultrasound‐Assisted Removal of Rifampin in the Presence of N: ZnO/GO Nanocomposite as Sonocatalyst

AbstractThe sonocatalytic Removal of Rifampin by Nitrogen‐doped Zinc oxide/Graphene oxide hybrid nanocomposite (N: ZnO/GO) is reported in this study. The structural properties of the nanocomposites were confirmed by the X‐ray diffraction (XRD), the scanning electron microscopy (SEM), the transmission electron microscopy (TEM), the X‐ray energy spectroscopy (EDX) and the diffraction reflectance spectroscopy (DRS). The experiments were investigated by applying the Response Surface Methodology (RSM) using the Design of Experiments software. Analysis of variance (ANOVA) confirmed that the quadratic model has good reliability for predicting the sonocatalytic efficiency with different operational factors (R2=0.9958 and Adjusted R2=0.9920). According to the RSM data, the optimized nanocomposite (N: ZnO (0.2 M)/GO (0.1 g)) demonstrated a reasonable catalytic activity for sonocatalytic degradation of RIF at the initial concentration (30 mg L−1), the ultrasonic irradiation time (60 min), natural pH and under the ultrasonic irradiation power of 400 W with a reaction rate constant of 0.0466 min−1which was higher compared with the other ones. The residual RIF amount has determined by the spectrophotometric method. The percentage of the RIF minerals was 80.8 % after 60 min of RIF degradation over N: ZnO (0.2 M)/GO.

Active Synthesis of Graphene Nanosheet-Embedded PbS Octahedral Nanocubes for Prompt Sonocatalytic Degradation

PbS octahedral cubic crystals were embedded in graphene nanosheets (GNS) which were synthesized using the autoclave method and utilized for the sonocatalytic degradation of Methylene blue (MB) and Congo red (CR) dye. The effects of the photocatalytic activity were investigated with two different dyes using a similar time interval. The graphene nanosheet-supported PbS octahedral nanocubes (GNS@PbS) displays excellent degradation within 10 min in the presence of sonochemical treatment. Sonocatalytic treatment reveals that more effective OH groups are produced from the hot spots, which helped to enhance the degradation of the dyes. Further, the addition of hydrogen peroxide (H2O2) led to more rapid degradation of MB dye compared with CR dye.

Systematic activation of potassium peroxydisulfate with ZIF-8 via sono-assisted catalytic process: Mechanism and ecotoxicological analysis

Abstract Powerful and suitable combination of different advanced oxidation processes (AOPs) has raised a new challenge in recent years. Since the generation of synergistic phenomenon is vital in the final integrated process, there is still an urgent demand for developing a superior hybrid AOPs, which is synergistically effective, simply and economically prepared and operated. Herein, a novel combination of ZIF-8 nanomaterials (NMs) and sonolysis process was utilised for efficient activation of potassium peroxydisulfate (PDS), leading to the establishment of a novel combined sono-assisted indirect photocatalytic process. ZIF-8 NMs were fabricated by a facial and green synthesis method at room temperature. The XRD, TEM, and BET analyses confirmed the successful production of porous ZIF-8 nanomaterials with sodalite (SOD) topology and hexagonal shapes including the specific surface area of 1484.28 m2/g. Besides, the effects of operational parameters including pH, ZIF-8, and PDS, Acid Blue 7 (AB7) concentration and ultrasonic bath power (UBP) were investigated on three response parameters consisting of AB7 removal efficiency (RE (%)), pseudo-first-order kinetic rate constant (kapp) and synergistic factor (SF). Optimum operating conditions were determined as pH = 5, [ZIF-8] = 0.6 g/L, [PDS] = 0.6 mmol/L in which maximum SF of 1.45 was achieved. The concurrent decomposition of S2O82−, HSO5−, H2O2, and AB7 on the active sites of ZIF-8 NMs were responsible for degradation. Based on the identified by-products via GC–MS technique, the AB7 sonocatalytic degradation mechanism was proposed. Finally, valuable efforts were made to assess the ecotoxicological effects of AB7, ZIF-8 NMs and the produced intermediates under optimised operating conditions. Sono-assisted indirect photocatalytic process in the presence of ZIF-8 NMs activated PDS can be noticed as an acceptable and green integrated process due to its high SF and novel features.

Ultrasound-engineered synthesis of WS2@CeO2 heterostructure for sonocatalytic degradation of tylosin.

The main aim of the present investigation was the intercalation of WS2 nanosheets in the structure of ceria (CeO2) to be used for the efficient catalytic destruction of tylosin (TYL) as a macrolide antibiotic in water. As-synthesized heterostructured catalyst was placed in a sono-reactor (40kHz and 300W) in order to degrade TYL through the sonocatalysis. 15wt% WS2/CeO2 was chosen for performing the systematic experiments. Decreasing the concentration of TYL, along with increasing the WS2/CeO2 dosage led to reduced degradation efficiency. The water hardness was demonstrated to be a suppressive agent on the sonocatalysis of the target pollutant. As-generated holes, OH, and also O2- were responsible for the degradation of TYL. Increasing the ultrasound power and operating temperature enhanced the degradation efficiency. The degradation rate boosted up when the temperature was raised from 10°C (0.0107 1/min) to 40°C (0.0165 1/min). Moreover, the lowest activation energy (Ea) for sonocatalytic degradation was obtained as 10.81kJ/mol. The sonocatalytic activity of WS2/CeO2 in the sono-reactor encountered insignificant change within five consecutive operational runs (~15% reduction). The mechanism and pathways of the sonocatalytic decomposition of TYL are also proposed.

Construction of Z‐scheme Pt‐TiO2/(Er3+:Y3Al5O12@Ta2O5)/HAP and its application in sonocatalytic degradation of prometryn and disinfection of Escherichia coli

AbstractBACKGROUNDThe recovery and reuse of sonocatalysts are the pivotal issues in the sonocatalytic degradation of organic pollutants. The use of some natural minerals as the carrier is not only beneficial to recycling of sonocatalysts, but also reduces the treatment costs of organic pollutants. Two kinds of hydroxyapatite (HAP), Ox Bone (OB)‐HAP and synthesized (Syn)‐HAP combine with the Pt‐TiO2/(Er3+:Y3Al5O12@Ta2O5) (P‐TET) composite, obtaining two Z‐scheme sonocatalysts, P‐TET/OB‐HAP and P‐TET/Syn‐HAP, respectively. The sonocatalytic activities of the prepared samples are investigated via degradation of prometryn and disinfection of Escherichia coli.RESULTSA series of characterizations showed that the Z‐scheme P‐TET/(OB or Syn)‐HAP sonocatalysts were prepared successfully. To evaluate their sonocatalytic activities, some influencing factors such as ultrasonic irradiation time, inorganic oxidants, used times and trapping agents on the sonocatalytic degradation prometryn were determined. The best degradation ratio (80.31% based on N computing and 85.07% based on S atom computing) of prometryn could be obtained for 10 mmol L−1 K2S2O8, 1.0 g L−1 P‐TET/OB‐HAP sonocatalyst and 150 min ultrasonic irradiation. The excellent sonocatalytic disinfection ratio (88.65%) of E. coli could also be obtained under 40 min ultrasound irradiation. Moreover, a possible mechanism on sonocatalytic degradation of prometryn was illustrated.CONCLUSIONThe treated bovine bone HAP was directly used as a carrier to combine with P‐TET to construct a novel Z‐scheme P‐TET/OB‐HAP sonocatalyst. The high degradation ratio of prometryn and disinfection ratio of E. coli showed that P‐TET/OB‐HAP could be a promising sonocatalyst for the degradation of organic pollutants and the disinfection of bacteria. © 2020 Society of Chemical Industry

Distinctive binary g-C3N4/MoS2 heterojunctions with highly efficient ultrasonic catalytic degradation for levofloxacin and methylene blue

Sonocatalytic degradation was considered as a new and advanced strategy for the elimination of hazardous organic pollutants from wastewater. Until now, the synergy of employing ultrasonic irradiation with g–C3N4–based catalysts for the removal of antibiotic residues is rarely reported. In this paper, a binary g-C3N4/MoS2 heterojunctions was successfully fabricated by using a facile hydrothermal strategy and applied to investigate the degradation efficiency of levofloxacin and methylene blue (MB) under ultrasonic condition for the first time. Physicochemical characterizations indicated that MoS2 particles presented irregular shapes with 80 nm and adhered onto the surface of g-C3N4 micro-rods with different lengths ranging from 2 to 5 μm. The ultrasonic degradation experiments indicated that g-C3N4/MoS2 could eliminate 75.81% of levofloxacin within 140 min and 98.43% of MB in 14 min with excellent recyclability. The excellent activity and stability could mainly be attributed to synergetic effects including (1) highly efficient separation and transfer system of sono-generated charge from g-C3N4 to MoS2; (2) typical sonoluminescence and transient cavitation effects in ultrasonic system are apt to increase the radical generation and (3) keeping the interspaces and reactive sites clean by continuous strong surface cleaning. The reactive species detecting experiments revealed that the •OH and •O2- played key roles in MB degradation. Furthermore, a possible mechanism for ultrasonic catalytic performance of g-C3N4 enhanced by MoS2 was proposed based on the detail analysis of the band gaps of g-C3N4 and MoS2, together with the “hot spot” theory of ultrasonication. This work gives an effective and alternative approach for the removal of antibiotic residues and organic dyes in wastewater.

Ultrasonically Induced Sulfur-Doped Carbon Nitride/Cobalt Ferrite Nanocomposite for Efficient Sonocatalytic Removal of Organic Dyes

The sulfur-doped carbon nitride/cobalt ferrite nanocomposite (SCN/CoFe2O4) was prepared via ultrasonication and studied for the sonocatalytic degradation of wastewater organic dye pollutants including methylene blue, rhodamine B, and Congo red. The X-ray photoelectron spectroscopy confirmed the presence and atomic ratios of S, C, N, Co, Fe, and O elements and their corresponding bonds with Co2+ and Fe3+ cations. The nanocomposite was found to have aggregated nanoparticles on a sheet-like structure. The bandgap energy was estimated to be 1.85 eV. For the sonocatalytic degradation of 25-ppm methylene blue at 20 kHz, 1 W and 50% amplitude, the best operating condition was determined to be 1 g/L of catalyst dosage and 4 vol % of hydrogen peroxide loading. Under this condition, the sonocatalytic removal efficiency was the highest at 96% within a reaction period of 20 min. SCN/CoFe2O4 outperformed SCN and CoFe2O4 by 2.2 and 6.8 times, respectively. The SCN/CoFe2O4 nanocomposite was also found to have good reusability with a drop of only 7% after the fifth cycle. However, the degradation efficiencies were low when tested with rhodamine B and Congo red due to difference in dye sizes, structural compositions, and electric charges.

Fabrication of a novel magnetic CdS nanorod/NiFe2O4/NaX zeolite nanocomposite with enhanced sonocatalytic performance in the degradation of organic dyes

Herein, magnetically separable CdS nanorods (NRs)/NiFe2O4/NaX zeolite ternary nanocomposite was fabricated and applied for the enhanced sonocatalytic degradation of organic dyes.

MIL-101(Cr)-cobalt ferrite magnetic nanocomposite: synthesis, characterization and applications for the sonocatalytic degradation of organic dye pollutants.

In this study, for the first time, a novel magnetically recyclable MIL-101(Cr)/CoFe2O4 nanocomposite was prepared via a facile solvothermal method. The morphology, structural, magnetic and optical properties of the nanocomposite were characterized via field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), UV-visible spectroscopy (UV-visible) and BET surface area analysis. Furthermore, the sonocatalytic activity of the MIL-101(Cr)-based magnetic nanocomposite was explored for the degradation of organic dye pollutants such as Rhodamine B (RhB) and methyl orange (MO) under ultrasound irradiation in the presence of H2O2. Under optimized conditions, the degradation efficiency reached 96% for RhB and 88% for MO. The sonocatalytic activity of MIL-101(Cr)/CoFe2O4 was almost 12 and 4 times higher than that of the raw MIL-101(Cr) and pure CoFe2O4, respectively. The improved sonocatalytic performance of the as-prepared binary nanocomposite can be attributed to the relatively high specific surface area of MIL-101(Cr) and magnetic property of CoFe2O4, as well as the fast generation and separation of charge carriers (electrons and holes) in MIL-101(Cr) and CoFe2O4. In addition, the trapping tests demonstrated that ·OH radicals are the main active species in the dye degradation process. Moreover, the most influencing factors on the sonocatalytic activity such as the H2O2 amount, initial dye concentration and catalyst dosage were investigated. Finally, the nanocomposite was magnetically separated and reused without any observable change in its structure and performance even after four consecutive runs.

Magnetic separable zeolite-type ZSM-5/CdS nanorods/MoS2nanoflowers/MnFe2O4quaternary nanocomposites: synthesis and application of sonocatalytic activities

Magnetic zeolite-type ZSM-5/CdS nanorods/MoS2nanoflowers/MnFe2O4quaternary nanocomposites were synthesized and used for the sonocatalytic degradation of organic pollutants.

Green synthesis of garlic extract stabilized Ag@CeO2 composites for photocatalytic and sonocatalytic degradation of mixed dyes and antimicrobial studies

Noble metals combined metal oxide composites have synergistic contributions to plasmonic catalysis caused by surface plasmon resonance (SPR) has emerged out as an impressive way for efficient light absorption and solar light conversion. In this work, a new approach was proposed to prepare noble metal-based CeO2 composites for the degradation of single and mixed dyes under natural sunlight and ultrasound irradiation. The garlic extract stabilized Ag@CeO2 composite was successfully prepared by Ag nanoparticles (NPs) on the surface of CeO2 via a simple method. The synthesized Ag NPs, CeO2 NPs, and Ag@CeO2 composite were investigated to determine its structural, optical, and morphological properties using powder XRD, UV–vis DRS, PL, BET, and TEM characterization techniques. The synthesized Ag@CeO2 composite having high purity and well-crystalline with an average size of ∼5–15 nm. The Ag@CeO2 composites were utilized as photocatalyst for degradation of single dyes (methylene blue; MB and methyl orange; MO) and mixed dye (MB + MO) under sunlight and ultrasound irradiation, showing the almost inclusive degradation of MB, MO and MB + MO in 30 min due to the fast electron transfer from Ag to CeO2 and surface plasmon resonance. In addition, they were also found to possess good stability and recyclability. Moreover, the possible photocatalytic mechanism for the degradation of dyes was also proposed. The synthesized Ag@CeO2 composites were further investigated for their antimicrobial activity towards several bacteria and fungi strains. The obtained results for Ag@CeO2 have displayed the significantly improved catalytic and antibacterial properties in comparison with pure CeO2 and Ag NPs.

Sonocatalytic degradation of caffeine using CeO2 catalyst: parametric and reusability studies

This work examined sonocatalytic degradation of caffeine in the presence of CeO2 prepared by hydrothermal method. Several characterization techniques were used to study the CeO2 including TEM, XRD and BET method. Effects of various parameters such as pH, initial concentration of caffeine and dosage of CeO2 were investigated. This study also examined the reusability of CeO2. Results showed that the CeO2 had mixed shapes of crystallites consisting of rods and cubes with the specific surface area (Sbet) and pore volume of 126.63 m2/g and 0.4898 cm3/g, respectively. About 95.5% of caffeine degradation was achieved under the best parameter conditions i.e. at pH of 7.5, 5.0 mg/L of initial concentration of caffeine and 1.0 g/L of CeO2 dosage within 150 min. It was also revealed that the operating parameters played major roles in caffeine degradation efficiency. In addition, the CeO2 were quite stable since the efficiency of caffeine degradation achieved in the third cycle was 81.4%.

Biosynthesized Fe- and Ag-doped ZnO nanoparticles using aqueous extract of Clitoria ternatea Linn for enhancement of sonocatalytic degradation of Congo red.

Nowadays, the current synthesis techniques used in industrial production of nanoparticles have been generally regarded as nonenvironmentally friendly. Consequently, the biosynthesis approach has been proposed as an alternative to reduce the usage of hazardous chemical compounds and harsh reaction conditions in the production of nanoparticles. In this work, pure, iron (Fe)-doped and silver (Ag)-doped zinc oxide (ZnO) nanoparticles were successfully synthesized through the green route using Clitoria ternatea Linn. The optical, chemical, and physical properties of the biosynthesized ZnO nanoparticles were then analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), UV-Vis diffuse reflectance spectroscopy (DRS), zeta potential measurement, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and surface analysis. The biosynthesized ZnO nanoparticles were crystallized with a hexagonal wurtzite structure and possessed smaller particle sizes than those of commercially or chemically produced samples. The existence of biomolecules to act as reducing and stabilizing agents from C. ternatea Linn aqueous extract was confirmed using FTIR analysis. The biosynthesized ZnO nanoparticles mainly comprised of negatively charged groups and responsible for moderately stable dispersion of the nanoparticles. All these properties were favorable for the sonocatalytic degradation of Congo red. Sonocatalytic activity of ZnO nanoparticles was studied through the degradation of 10 mg/L Congo red using ultrasonic irradiation at 45 kHz and 80 W. The results showed that the sonocatalytic degradation efficiency of Congo red in the presence of biosynthesized ZnO nanoparticles prepared at 50 °C for 1 h could achieve 88.76% after 1 h. The sonocatalytic degradation efficiency of Congo red in the presence of Ag-doped ZnO was accelerated to 94.42% after 10 min which might be related to the smallest band gap energy (3.02 eV) and the highest specific surface area (10.31 m2/g) as well as pore volume (0.0781 cm3/g). Lastly, the biosynthesized ZnO nanoparticles especially Ag-doped ZnO offered significant antibacterial potential against Escherichia coli which indicated its ability to inhibit the normal growth and replication of bacterial cells. These results affirmed that the biosynthesized ZnO nanoparticles could be used as an alternative to the current chemical compounds and showed a superior sonocatalytic activity toward degradation of Congo red.

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.

Studied on sonocatalytic degradation of Rhodamine B in aqueous solution.

This paper describes experimental results of degradation of Rhodamine B (RB) by vortex scattering ultrasound in aqueous solution. Vortices are produced by a high-speed agitator. The effects of different factors on the degradation of RB solution were studied, such as different reaction container, the initial concentration of RB, stirring speed and ultrasonic frequencies. Ultraviolet-visible spectrophotometer (UV) was used to measure the absorbance value of RB to assess degradation rate. The optimal experimental condition was three-necked bottle, stirring speed of 700 r/min, initial concentration of 10 mg/L and ultrasonic frequency of 40 kHz. The optimal degradation rate of RB can reach 98% within one hour. The combination of ultrasonic irradiation and mechanical stirring was discovered that can degrade the RB efficiently in aqueous solution. The investigation of mechanism demonstrates that the cavitation bubbles produced by agitation play a major role in promoting degradation. COMSOL Multiphysics (Version 5.3a) software was used to simulate this process. And the method of combination of ultrasonic irradiation and mechanical stirring has also been shown to be effective in degrading methylene blue, bromophenol blue and Congo red. So the combination of ultrasonic irradiation and mechanical stirring can be used as an option for treating organic wastewater in the future. This study established a new way to degrade other organic pollutants.

MoS2/RGO hybrids prepared by a hydrothermal route as a highly efficient catalytic for sonocatalytic degradation of methylene blue

Abstract In this paper, the MoS2/RGO hybrids were successfully prepared via a one-pot hydrothermal. The MoS2/RGO was used for sonocatalytic degradation of methylene blue (MB) for the first time. It exhibited high sonocatalytic performance under ultrasound (US) irradiation than that of pure MoS2. Then the MoS2/RGO hybrids are well analyzed by various spectroscopic techniques such as TGA, X-Ray Diffraction, XPS, TEM, Raman, PL, UV–Vis and DRS etc. Furthermore, the sonocatalytic-degradation mechanism is discussed. The enhanced sonocatalytic performance of MoS2/RGO composites can be put down to that the heterojunction structure of MoS2/RGO can heighten the separation efficiency of the electron-hole pairs. The TEM images of the MoS2/RGO reveal that the RGO nanosheets had inserted into MoS2 layers. Thus, the template growth method based on GO expanded the interlayers of MoS2 so that it exposed a greater fraction of the catalytically active sites to offer a large surface area and improve the electronic conduction efficiency. This work provides an evidence that the MoS2/RGO possesses enormous potential in sonocatalytic applications.

A review on carbon-based materials for heterogeneous sonocatalysis: Fundamentals, properties and applications.

Contamination of water resources by refractory organic pollutants is of great environmental and health concern because these compounds are not degraded in the conventional wastewater treatment plants. In recent years, sonocatalytic treatment has been considered as a promising advanced oxidation technique for the acceptable degradation and mineralization of the recalcitrant organic compounds. For this purpose, various sonocatalysts have been utilized in order to accelerate the degradation process. The present review paper provides a summary of published studies on the sonocatalytic degradation of various organic pollutants based on the application of carbon-based catalysts, including carbon nanotubes (CNTs), graphene (GR), graphene oxide (GO), reduced graphene oxide (rGO), activated carbon (AC), biochar (BC), graphitic carbon nitride (g-C3N4), carbon doped materials, buckminsterfullerene (C60) and mesoporous carbon. The mechanism of sonocatalytic degradation of different organic compounds by the carbon-based sonocatalysts has been well assessed based on the literature. Moreover, the details of experimental conditions such as sonocatalyst dosage, solute concentration, ultrasound power, applied frequency, initial pH and reaction time related to each study have also been discussed in this review. Finally, concluding remarks as well as future challenges in this research field regarding new areas of study are also discussed and recommended.

Heterogeneous sonocatalytic degradation of an anionic dye in aqueous solution using a magnetic lanthanum dioxide carbonate-doped zinc ferrite-reduced graphene oxide nanostructure

We report herein the sonochemical synthesis of a lanthanum dioxide carbonate (La2O2CO3) and zinc ferrite (ZnFe2O4)-loaded reduced graphene oxide (LZF-rGO) nanoheterostructure for ultrasound (US)-assisted degradation of methyl orange (MO) from water. The MO was chosen as a model organic dye due to its toxicological and biodegradable-resistant properties. The LZF-rGO catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results of characterizations confirmed successful synthesis of sonocatalyst. Among different removal systems, US/LZF-rGO displayed outstanding sonodegradation performance for degradation of MO. The maximum removal efficiency of 75.9% was achieved using 0.2 g/L sonocatalyst, 20 mg/L MO, and 0.71 W/cm2 US power intensity for 65 min. MO can be partially adsorbed on LZF-rGO but mostly sonodegraded by reactive radical species. The reaction conditions were optimized by investigating the effect of key operating parameters, including the sonocatalyst dosage, initial MO concentration, US power intensity, presence of inorganic salts, and use of an enhancer, on the decolorization of MO. The degradation intermediates produced from MO during the sonocatalytic process were identified by UPLC®/MS-MS, and possible mechanism and pathway for the degradation of MO in the US/LZF-rGO system were also proposed. Reusability experiments with this sonocatalyst revealed a less than 10% drop in the degradation efficiency after four adsorption–desorption cycles.

Preparation of a novel Z-scheme KTaO3/FeVO4/Bi2O3 nanocomposite for efficient sonocatalytic degradation of ceftriaxone sodium

In this work, a novel Z-scheme sonocatalyst, KTaO3/FeVO4/Bi2O3, is prepared via ultrasonic-assisted isoelectric point method. The prepared samples are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectroscopy. The catalytic activity of Z-scheme KTaO3/FeVO4/Bi2O3 sonocatalyst is studied in degradation of ceftriaxone sodium under ultrasonic irradiation. In addition, the influences of ultrasonic irradiation time, scavengers and sonocatalyst used times on sonocatalytic degradation of ceftriaxone sodium are examined. Under the experimental conditions of 150 min ultrasonic irradiation time, 1.00 g/L KTaO3/FeVO4/Bi2O3 addition amount and 10.00 mg/L ceftriaxone sodium concentration, the sonocatalytic degradation ratio of ceftriaxone sodium achieves 81.30%. Finally, the possible sonocatalytic degradation mechanism of ceftriaxone sodium caused by Z-scheme KTaO3/FeVO4/Bi2O3 sonocatalyst is proposed. The enhanced sonocatalytic activity may be attributed to the fact that the FeVO4 as a special conductive channel provides a strong driving force to transfer electrons through valence state changes of iron and vanadium, which accelerates electron transfer from conduction band (CB) of Bi2O3 to valence band (VB) of KTaO3. Perhaps, the KTaO3/FeVO4/Bi2O3 composite is an excellent Z-scheme sonocatalyst which can be used to effectively degrade the organic pollutants in wastewater under ultrasonic irradiation.

Performance assessment of the combined treatment for oxytetracycline antibiotics removal by sonocatalysis and degradation using Pseudomonas aeruginosa

A facile method was applied to achieve complete degradation of oxytetracycline to carbon dioxide and water. In most abiotic degradation, it fails to degrade oxytetracycline to non-toxic products and leaves some intermediates. In this study, sonocatalytic degradation was performed to degrade the more toxic oxytetracycline to less toxic intermediates. In addition, the above intermediates was degraded by biological method, by providing these intermediates as carbon source for bacteria. In the sono degradation process, ZnO was used as sonocatalyst material, which was prepared by simple chemical precipitation method. At first 30 min removal of oxytetracycline was achieved by adsorption and following 30 min will be degraded under ultra-sonication. In addition, sodium peroxydisulfate was used to achieve complete degradation of oxytetracycline. For the best degradation, various parameters such as pH, temperature, dosage of ZnO and concentration of peroxydisulfate, were optimized. At a pH 7, temperature of 55 oC, ZnO dosage of 3 g L-1 and peroxydisulfate concentration of 1 g L-1, the removal efficiency is nearly 99% at the end of 60 min for initial oxytetracycline concentration of 2 ppm. After sonocatalytic degradation, the intermediate formed was naphthalene and was confirmed in this study. Pseudomonas aeruginosa was used for biodegradation of intermediates. This strain is best for using various aromatic compounds as carbon source as it can easily break naphthal rings using naphthalene dehydrogenase enzymes. The removal performance of oxytetracycline and intermediates by sono-bio catalytic degradation was also confirmed by analyzing the total organic carbon (TOC) concentration in the test sample.