Sonophotocatalytic Activity Research Articles

Ultrasonically synthesized N-TiO2/Ti3C2 composites: Enhancing sonophotocatalytic activity for pollutant degradation and nitrogen fixation

A series of N-TiO 2 /Ti 3 C 2 composites are constructed via ultrasonically treating pre-synthesized N-TiO 2 and Ti 3 C 2 . Improved sonophotocatalytic activity is demonstrated by the tests of contaminant degradation and nitrogen fixation. • The N-TiO 2 /Ti 3 C 2 composites are constructed under ultrasound irradiation. • The intimate interfacial contact is verified by a series of characterizations. • Improved sonophotocatalytic degradation and nitrogen fixation are confirmed. • The synergic effect of N 2p doping and Ti 3 C 2 coupling contribute to the enhancement. • The order of catalytic behavior was sonophotocatalysis＞sonocatalysis＞photocatalysis. Herein, a series of N-TiO 2 /Ti 3 C 2 (N-TTC x ) composites are constructed via ultrasonically treating pre-synthesized N doped TiO 2 and Ti 3 C 2 at room temperature. The intimate contact between N-TiO 2 and Ti 3 C 2 is verified by the transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. And, the N-TTC 0.06 composites exhibit the best sonophotocatalytic performance, which is 1.9 times and 8.8 folds higher than that of TiO 2 for pollutant degradation and nitrogen fixation, respectively. What’s more, sonophotocatalytic degradation of pollutants and nitrogen fixation shows larger efficiency compared with that of photocatalysis and sonocatalysis, which is attributed to the synergistic effect between sonocatalysis and photocatalysis in the sonophotocatalytic process. Moreover, taking N-TTC 0.06 for example, the three cycles of sonophotocatalytic degradation of Rh-B and nitrogen fixation as well as the unchanged X-ray diffraction before and after sonophotocatalytic nitrogen fixation all confirm the stable sonophotocatalytic behavior of N-TiO 2 /Ti 3 C 2 composites. The improved sonophotocatalytic activity is attributed to the decrease of band gap by N 2p doping level and the separation/transfer improvement of photoinduced carriers by Ti 3 C 2 , which are demonstrated by UV–vis absorption spectra, photoelectrochemical tests, Nyquists plots, and Mott-schottky plots. This study confirms that the designed N-TiO 2 /Ti 3 C 2 composites exhibit great potential application in sonophotocatalytic pollutant degradation and nitrogen fixation.

A novel Sm doped Cr2O3 sesquioxide-decorated MWCNTs heterostructured Fenton-like with sonophotocatalytic activities under visible light irradiation

Novel Sm doped Cr2O3 decorated MWCNTs nanocomposite photocatalyst was successfully prepared by a facile hydrothermal method for metoprolol (MET) degradation. A heterogeneous photo -Fenton like system was formed with the addition of H2O2 for ultrasonic irradiation (US), visible light irradiation (Vis) and dual irradiation (US/Vis) systems. The intrinsic characteristics of Sm doped Cr2O3 decorated MWCNTs nanocomposite was comprehensively performed using state-of-art characterization tools. Optical studies confirmed that Sm doping shifted the absorbance of Cr2O3 towards the visible-light region, further enhanced by MWCNTs incorporation. In this study, degradation of metoprolol (MET) was investigated in the presence of Cr2O3 nanoparticles, Sm doped Cr2O3 and Sm doped Cr2O3 decorated MWCNTs nanocomposites using sonocatalysis and photocatalysis and simultaneously. Several different experimental parameters, including irradiation time, H2O2 concentration, catalyst amount, initial concentration, and pH value, were optimized. The remarkably enhanced sonophotocatalytic activity of Sm doped Cr2O3 decorated MWCNTs could be attributed to the more formation of reactive radicals and the excellent electronical property of Sm doping and MWCNTs. The rate constant of degradation using sonophotocatalytic system was even higher than the sum of rates of individual systems due to its synergistic performance based on the kinetic data. A plausible mechanism for the degradation of MET over Sm-Cr2O3/MWCNTs is also demonstrated by using active species scavenger studies and EPR spectroscopy. Our findings imply that (•OH), (h+) and (•O2−) were the reactive species responsible for the degradation of MET based on the special three-way Fenton-like mechanism and the dissociation of H2O2. The durability and stability of the nanocomposite were also performed, and the obtained results revealed that the catalysts can endure the harsh sonophotocatalytic conditions even after fifth cycles. Mineralization experiments using the optimized parameters were evaluated as well. The kinetics and the reaction mechanism with the possible reasons for the synergistic effect were presented. Identification of degraded intermediates also investigated.

Construction of S-scheme 1D/2D rod-like g-C3N4/V2O5 heterostructure with enhanced sonophotocatalytic degradation for Tetracycline antibiotics

Pharmaceutically active compounds are an emerging water contaminant that resists conventional wastewater treatments. Herein, the sonophotocatalytic degradation of Tetracycline (TC) antibiotics as a model contaminant was carried out over a rod-like g-C3N4/V2O5 (RCN-VO) nanocomposite. RCN-VO nanocomposite was synthesized via ultrasound-assisted thermal polycondensation method. The results showed that the RCN-VO nanocomposite could completely remove the TC in water within 60 min under simultaneous irradiation of visible light and ultrasound. Moreover, the sonophotocatalytic TC degradation (a synergy index of ∼1.5) was superior to the sum of individual sonocatalytic and photocatalytic degradation using RCN-VO nanocomposite. Besides, the enhanced sonophotocatalytic activity of RCN-VO can be attributed to the 1D/2D nanostructure and the S-scheme heterojunction formation between RCN and VO where the electrons migrated from RCN to VO across the RCN-VO interface. Under irradiation, the built-in electric field, band edge bending and Coulomb interaction can synergistically facilitate the unavailing electron-hole pair recombination. Thereby, the cumulative electron in RCN and holes in VO can actively take part in the redox reaction which generates free radicals and attack the TC molecules. This study provides insight into a novel S-Scheme heterojunction photocatalyst for the removal of various refractory contaminants via sonophotocatalytic degradation.

Ultrasonic assisted photocatalytic process for degradation of ciprofloxacin using TiO2-Pd nanocomposite immobilized on pumice stone

Herein, Pumice (PM)-TiO2-Pd nanocomposite as an efficient catalyst was prepared by modified sol-gel method and used for sonophotocatalytic removal of ciprofloxacin (CIP). Various analyses were used to investigate the properties of the catalysts. Based on the SEM results, the TiO2 and Pd nanoparticles on the PM surface were immobilized regularly without aggregation. Also, the crystalline structure and functional groups of PM-TiO2-Pd nanocomposite were identified successfully by XRD and FTIR analyses. The bandgap energy of 2.52, 3.17, and 3.29 eV were calculated for PM-TiO2-Pd, PM-TiO2, and PM indicating higher sonophotocatalytic activity of PM-TiO2-Pd nanocomposite. 79.44 % of CIP was removed within 120 min of treatment time using in the optimum condition ([PM-TiO2-Pd] = 0.5 g/L, [CIP]0 = 20 mg/L and pH = 6). By adding radical scavengers like EDTA, CrO3, formic acid, and enhancers like K2S2O8 and H2O2 the degradation efficiency was as follows respectively: 37.72, 31.71, 28.29, 88.78, and 72.43%. The reusability and stability of the composite after four consecutive runs was decreased only 9.44%. Also, 8 intermediate byproducts generated under sonophotocatalytic degradation of CIP by PM-TiO2-Pd nanocomposite were identified.

Sonophotocatalytic degradation of organic pollutant under visible light over Pt decorated CeO2: Role of ultrasonic waves for unprecedented degradation

Sonophotocatalysis is an innovative energy transfer technique proposed to produce solar energy and environmental remediation. Herein, we designed platinum (Pt) decorated CeO2 and applied it as sonophotocatalyst for pollutant degradation. Sonophotocatalytic activity of the as-prepared Pt/CeO2 nanocomposite was carried out at 40 kHz frequency ultrasonic waves under visible light irradiation. The sonophotocatalytic degradation efficiency of Acid Red 17 over Pt/CeO2 nanocomposite is much higher when compared to photocatalytic degradation. This unprecedented sonophotoactivity is credited to ultrasonic waves that generate additional OH• free radicals by scavengers test. The effect of various operational conditions like pH, amount of catalyst, and concentration of acid red 17 dye were also studied. More intriguingly, the sonophotoactivity of the optimized amount remains high and almost unchanged for up to four cycles, indicating the stability of the sonophotocatalyst. This steady progress has exemplified that Pt/CeO2 nanocomposites are playing and will continue to play an indispensable role in solar energy production and environmental remediation.

Solochrome Dark Blue Azo Dye Removal by Sonophotocatalysis Using Mn2+ Doped ZnS Quantum Dots

This work investigates the degradation of the azo dye solochrome dark blue (SDB) by measurement of the photocatalytic, sonocatalytic and sonophotocatalytic activities, under low ultrasonic frequency (40 kHz) and UV-C (254 nm) light, using Mn-doped ZnS semiconductor quantum dots (Mn2+:ZnS Qds) as catalysts, prepared by a simple chemical precipitation procedure. In order to study the different morphological and optical crystal properties, various characterization techniques were used, such as high resolution transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, N2 adsorption-desorption at −196 °C and ultraviolet-visible spectroscopy. The average particle size of the semiconductor Qds was in the range of 3–4 nm. The optimal parameters affecting dye degradation, such as the catalyst loading, solution pH, time of irradiation, initial concentration of dye, dopant concentration, ultrasonic power and frequency effect were evaluated. The synthesized catalytic material exhibited a high activity for sonophotocatalytic degradation of SDB (89%), larger than that observed for sonocatalysis (69.7%) or photocatalysis (55.2%) alone, which was due to the improved electron-holes separation, formation of more reactive radicals and enhancement of the active surface area. Qds showed good stability and reusability after five repeated cycles. Finally, the degradation products were identified by liquid chromatography-mass spectrometry (LC-MS).

Investigation on the formation, structural and photocatalytic properties of mixed Mn-Zn ferrites nanoparticles embedded in SiO2 matrix

The structure, morphology and photocatalytic features of the Mn-Zn ferrite nanoparticles embedded in SiO2 matrix produced by a modified sol-gel synthesis were investigated. The synthesis consists of mixing the metal nitrates, 1,4-butanediol and tetraethylorthosilicate, formation of the SiO2 matrix by gelation, formation of the metallic succinate precursors by heating the gel up to 200 °C and formation of the ferrite system by thermal treatment at higher temperatures. The formation of Mn-, Zn- and Fe-succinate precursors up to 200 °C and their decomposition into ferrites up to 400 °C was confirmed both by thermal analysis and Fourier-transform infrared spectroscopy. The X-ray diffraction provided information on the crystalline phases, crystallite size and lattice constant, while the morphology of the samples was investigated by transmission electron microscopy. The crystallite size increased (30.5–53.4 nm), while the energy band gap of the samples decreased (2.09−1.33 eV) with the increase of the Mn content in the ferrite; thus, the amount of manganese nitrate used in the synthesis could be an easy tailoring approach of the mixed Mn-Zn ferrites. All samples showed sonophotocatalytic activity, being able to degrade Rhodamine B under visible light irradiation, Mn0.3Zn0.7Fe2O4@SiO2 sample having the best sonophotocatalytic performance.

Graphene-based ZnCr layered double hydroxide nanocomposites as bactericidal agents with high sonophotocatalytic performances for degradation of rifampicin

Herein, ZnCr layered double hydroxide (ZnCr LDH), and its nanocomposites with GO and rGO were synthesized using the co-precipitation method. The samples were characterized using XRD, FT-IR, SEM, TEM, BET, and XPS techniques. The sonophotocatalytic activity of the ZnCr LDH, ZnCr LDH/GO, and ZnCr LDH/rGO was investigated via the degradation of rifampicin (RIF) in the ultrasonic bath under visible light irradiation. The synergy index of more than 1 determined for ZnCr LDH/rGO indicated the positive interaction of sonocatalysis and photocatalysis resulted by hybridizing the LDH nanosheets with rGO. The maximum sonophotocatalytic degradation efficiency of 87.3% was achieved in the presence of ZnCr LDH/rGO nanocomposite with the concentration of 1.5 g L−1 for degradation of RIF with an initial concentration of 15 mg L−1 within 60 min sonication under visible light irradiation. The addition of different scavengers indicated that hydroxyl radicals, superoxide anion radicals, and the generated holes played a dominant role in the degradation of the pollutant molecules. A possible degradation mechanism was suggested based on the intermediates. The antibacterial tests confirmed the higher antibacterial activity of ZnCr LDH/GO compared with ZnCr LDH and ZnCr LDH/rGO against Gram-positive Staphylococcus aureus.

Instantaneous Sonophotocatalytic Degradation of Tetracycline over NU-1000@ZnIn2S4 Core-Shell Nanorods as a Robust and Eco-friendly Catalyst.

The universal pollution of diverse water bodies and declined water quality represent very important environmental problems. The development of new and efficient photocatalytic water treatment systems based on the Z-scheme mechanisms can contribute to tackling such problems. This study reports the preparation, full characterization, and detailed sonophotocatalytic activity of a new series of hybrid NU@ZIS nanocomposites, which comprise a p-n heterojunction of 3D Zr(IV) metal-organic framework nanorods (NU-1000) and photoactive ZnIn2S4 (ZIS) nanostars. Among the obtained materials with varying content of ZIS (5, 10, 20, and 30%) on the surface of NU-1000, the NU@ZIS20 nanocomposite revealed an ultrahigh catalytic performance and recyclability in a quick visible-light-induced degradation of the tetracycline antibiotic in water under sonophotocatalytic conditions. Moreover, increased activity of NU@ZIS20 can be ascribed to the formation of a p-n heterojunction between NU-1000 and ZIS, and a synergistic effect of these components, leading to a high level of radical production, facilitating a Z-scheme charge carrier transfer and reducing the recombination of charge carriers. The radical trapping tests revealed that •OH, •O2-, and h+ are the major active species in the sonophotocatalytic degradation of tetracycline. Possible mechanism and mineralization pathways were introduced. Cytotoxicity of NU@ZIS20 and aquatic toxicity of water samples after tetracycline degradation were also assessed, showing good biocompatibility of the catalyst and efficacy of sonophotocatalytic protocols to produce water that does not affect the growth of bacteria. Finally, the obtained nanocomposites and developed photocatalytic processes can represent an interesting approach toward diverse environmental applications in water remediation and the elimination of other types of organic pollutants.

Modified Y2O3-coated biosilica with Dysprosium nanomaterials: synthesis, characterization, optical study with enhanced catalytic activity

Dy-doped Y2O3 coated biosilica nanostructures with variable Dy3+ contents were synthesized by a facile hydrothermal technique. The products were characterized by means of energy dispersive X-ray photoelectron spectroscopy (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), UV-Vis diffuse reflectance spectroscopy, and photoluminescence spectroscopy techniques. As claimed by XRD, the particles were crystallized excellently and attributed to the cubic phase of Y2O3. The influence of substitution of Dy3+ ions into Y2O3 lattice caused a redshift in the absorbance and a decrease in the bandgap of as-prepared coated compounds. The pore volume and BET specific surface area of Dy-doped Y2O3 -coated diatomite is greater than uncoated biosilica. The sonophotocatalytic activities of as-synthesized specimens were evaluated for the degradation of Reactive Blue 19. The effect of various specifications like ultrasonic power, various scavenger, and catalyst amount was explored. The results revealed that diatomite coated with Dy3+-incorporated yttrium oxide nanoparticles can be utilized in various experimental cycles with no significant drop in photocatalytic activity.

Preparation of MgTi2O5 nanoparticles for sonophotocatalytic degradation of triphenylmethane dyes

MgTi2O5 (magnesium dititanate) nanoparticles were prepared by a simple hydrothermal assisted post-annealing method and characterized with various analytical techniques. The catalytic properties (sonocatalytic, photocatalytic and sonophotocatalytic activity) were evaluated using the degradation of triphenylmethane dyes (crystal violet, basic fuchsin, and acid fuchsin). The sonophotocatalytic activity of MgTi2O5 nanoparticles towards crystal violet was found to be ~2.9 times higher than the photocatalytic activity and ~20 times higher than that of the sonocatalytic processes. In addition, the sonophotocatalytic efficiency of MgTi2O5 nanoparticles was found to be remarkable for the degradation of basic fuchsin (cationic dye) and acid fuchsin (anionic dye). The mechanism of these catalytic activities has been discussed in detail.

Synthesis and sonophotocatalytic activities of ZnO\\BiVO4\\Co3O4 composites

The composite photocatalysts ZnO/BiVO4 (35 wt%) and ZnO/BiVO4 (35 wt%)/Co3O4 (10 wt%) (ZBC) were hydrothermal synthesized and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and UV–Vis diffusion reflectance spectra techniques. The sonophotocatalytic activities of these composites were investigated by degrading brilliant green dye. Approximately 99.1% brilliant green dye was degraded within 60 min of visible light illumination using ZBC as the photocatalyst, which is much higher than the efficiency reported early. The multi-element heterojunction structure and the ultrasound effectively improve the photodegradation performance.

Rational construction of CeO2–ZrO2@MoS2 hybrid nanoflowers for enhanced sonophotocatalytic degradation of naproxen: Mechanisms and degradation pathways

This study proposed a novel heterogeneous sonophotocatalytic system to effectively treat pharmaceutical wastewater employing molybdenum disulfide (MoS2) decorated ceria (CeO2)-zirconia (ZrO2) ternary hybrid nanoflowers (CZx/100 M). The generation of dominant oxidizing species, both radical and nonradical, was deeply scrutinized under ultrasound (US) irradiation coupled with visible-light by electron spin resonance spectroscopy analysis and scavenging experiments, for the first time. Interestingly, the pairing of US with visible-light illumination in a sonophotocatalytic degradation system resulted in 96% degradation efficiency of naproxen (NPX) within 40 min, which confirmed that excellent synergistic effect of sono- and photocatalytic mechanisms in the presence of 0.5 g/L sonophotocatalyst at pH 5.8. The sonophotocatalytic activity was also manifested at various reaction time, catalyst dose, solution pH, initial NPX concentrations, and US frequency and power and in the presence of various anions. The mechanism for the catalytic degradation of NPX is proposed in the US/Vis/CZx/100 M system, and transformation products formed during the process were identified by an ultra-high performance liquid chromatography-mass spectrometry technique.

Sonochemical Synthesis, Characterization and Optical Properties of Tb-Doped CdSe Nanoparticles: Synergistic Effect between Photocatalysis and Sonocatalysis.

In this study, Tb-doped CdSe nanoparticles with variable Tb3+ content were synthesized by a simple sonochemical technique. The synthesized nanoparticles were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and powder X-ray diffraction (XRD). The sono-photocatalytic activities of the as-prepared specimens were assessed for the degradation of Reactive Black 5. The experimental results show that the sono-photocatalytic process (85.25%) produced a higher degradation percentage than the individual sono- (22%) and photocatalytic degradation (8%) processes for an initial dye concentration and Tb-doped CdSe dosage of 20 mg/L and 1 g/L, respectively. Response surface methodology (RSM) was utilized to assess model and optimize the impacts of the operational parameters, namely, the Tb3+ content, initial dye concentration, catalyst dosage, and time. The addition of benzoquinone results in remarkably inhibited degradation and the addition of ammonium oxalate reduced the removal percentage to 24%. Superoxide radicals and photogenerated holes were detected as the main oxidative species.

Preparation of CeO2/TiO2/NGP composites as efficient catalyst for removal of organic dye using photo-, sono-, and sonophotocatalytic activity

A simple hydrothermal technique was used to incorporate nanographene platelets (NGP) with CeO2/TiO2 composites with different NGP contents. The prepared samples were then evaluated as a heterogeneous catalyst to degrade methylene blue (MB) under visible light irradiation, ultrasonic irradiation, and a combination of the two. The structural and morphological properties of CeO2/TiO2/NGP composites were investigated by X-ray diffraction (XRD). The XRD spectra of CeO2/TiO2/NGP revealed the spectra of NGP, CeO2, and TiO2 nanoparticles indicating the desired combination. Further investigation using TGA measurements show that weight was lost at around 600 °C due to the combustion of carbon. The surface area of the composites was further increased. The prepared CeO2/TiO2–10 wt.% NGP composites were able to degrade MB four times higher than pristine CeO2/TiO2 composites, which may be due to a lower recombination rate; however, further increments of NGP decreased the degradation efficiency.

Synthesis of magnetic photocatalyst by photochemical deposition and co-precipitation techniques: investigation of its photocatalytic and sonophotocatalytic activity for dye removal

ABSTRACT In this study, photochemical deposition and co-precipitation methods were used to synthesise Ag/TiO2 and magnetic Ag/TiO2/Fe3O4 photocatalysts, respectively. The physical and chemical properties of the Ag/TiO2 and Ag/TiO2/Fe3O4 photocatalysts were characterised by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR) analyses. The synthesised photocatalysts were used to remove Reactive Red 195 (RR195) dye the most commonly used in the textile industry. The photocatalytic and sonophotocatalytic removal was investigated using different light types such as UV-A and visible light. In the optimum conditions (UV-A and visible light intensity 27 W, 25 mg/L initial RR195 concentration, pH 6 ve 0.1 g/L catalyst dose) of photocatalysis, the photodegradation of magnetic Ag/TiO2/Fe3O4 was found 72% at 120 min irradiation of visible light but the degradation was 65% at 30 min irradiation of UV-A light. While in case of the sonophotocatalysis, the degradation of magnetic Ag/TiO2/Fe3O4 was found 85% at 120 min irradiation of visible light but the degradation was 85% at 30 min irradiation of UV-A light.

Sonophotocatalytic Degradation of Pollutants by ZnO‐Based Catalysts: A Review

AbstractSonophotocatalyticprocess (SPC) is the simultaneous use of ultraviolet radiation (UV), ultrasonic radiation (US), and semiconductor materials as photocatalysts and sonocatalysts for the generation of reactive oxygen species (ROS). These free radicals oxidize several pollutant molecules in various industrial wastewaters. The objective of this review was to compare the papers published on the sonophotocatalytic degradation of different pollutants in the presence of zinc oxide‐based particles. The elimination rate of contaminants in this process was compared with individual methods such as sonocatalysis and photocatalysis. The experimental conditions, including the catalyst dosage, the pollutant concentration, the radiation power, the applied frequency, the initial pH, and the reaction time were further investigated. ZnO nanoparticles are well‐known as semiconductor materials with good sonophotocatalytic activity. In general, sonophotocatalysis is emerging as one of the most efficient treatment techniques for degrading the recalcitrant pollutants in the aqueous medium. It is expected that these technologies result in more progressive research with the most degradation efficiency.

Ce/Eu redox couple functionalized HKUST-1 MOF insight to sono-photodegradation of malathion

The Ce/Eu redox pair-functionalized HKUST-1 MOF, as an innovative environmentally friendly and recyclable sono-photocatalyst, was hydrothermally mixed and fully characterized by XRD, PL, EIS, FE-SEM, EDS, Mott-Schottky, chronoamperometry, and DRS techniques. The obtained chemical and optical characteristics of the n-type Ce/Eu-HKUST-1 MOF showed that the transfer of additional 4f orbital electrons in the Ce/Eu redox pair improves the sono-photocatalytic activity. The performance of Ce/Eu-HKUST-1 MOF for the sono-photodegradation of Malathion (MA) was evaluated in the aqueous media in the simultaneous presence of blue light and ultrasonic irradiation. The optimization of the process was cross-examined using the response surface methodology as a function of the MA concentration (15–35 mg·L−1), Ce/Eu-HKUST-1 mass (10–30 mg), pH (4−12), and ultrasonic wave irradiation duration (10–30 min). The maximum sono-photocatalytic degradation capacity was found to be 99.99% under the optimum conditions set as 25 mg·L−1, 20 mg, 8, and 25 min for the concentration of Malathion, photocatalyst mass, pH, and irradiation duration, respectively. These findings were attributed to the suppression of electron-hole pair recombination, increased life-time of charge carriers, enhanced visible light absorption, and prominent proportion of hydroxyl and peroxide radicals formed.

Intensification of the Orange II and Black 5 degradation by sonophotocatalysis using Ag-graphene oxide/TiO2 systems

The work aims to evaluate the sonophotocatalytic treatment (combination between photocatalytic activity and ultrasound) as an intensification process for removing pollutants such as azo dyes from water and wastewater. Four photocatalysts were prepared: TiO2 was doped with silver and graphene oxide to produce Ag/TiO2, graphene oxide/TiO2 and Ag-graphene oxide/TiO2 systems. Several analysis techniques, including SEM, XPS, were used to characterize the catalysts. The photocatalytic and sonophotocatalytic activity of all of the catalysts to degrade Orange II and Black 5 dyes was evaluated. Sheets of graphene oxide were identified on the spherical particles of TiO2, and some sheets were observed to be strongly bound to the titania. The existence of Ti-O-C bonds, Ti4+, Ag+, and metallic silver were determined. Combining photocatalysis (with UV light) and ultrasound has an intensifying and synergistic effect on the degradation rate of both dyes. The degradation kinetics were obtained. Orange II degradations were faster when UV light and TiO2_Ag_Graphene or TiO2_Ag catalysts were used. The highest degradation rates of Black 5 were obtained when the TiO2_Ag_Graphene, TiO2_Ag, or TiO2 catalysts were used. The highest degradation of the dyes was obtained at 1000 kHz and UV light.

Enhanced sonophotocatalytic degradation of paracetamol in the presence of Fe-doped TiO2 nanoparticles and H2O2

The presence of pharmaceutical compounds, particularly, paracetamol in water is of significant environmental concern due to their undesirable effects on aquatic organisms and poor biodegradability. The present work investigated the efficient degradation of paracetamol in water using sonophotocatalytic process in the presence of iron (Fe)-doped titanium dioxide (TiO2) nanoparticles. The effects of Fe doping into TiO2 and calcination temperatures were investigated using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, nitrogen adsorption–desorption analysis and X-ray photoelectron spectroscopy. It was discovered that 3 wt% Fe dopants into TiO2 nanoparticles with suitable calcination temperature at 600 °C could improve the sonophotocatalytic activity remarkably toward the degradation of paracetamol. The degradation efficiency of 100% was achieved under optimal experimental conditions, namely 5 mg/L initial paracetamol, 1 g/L 3 wt% Fe-doped TiO2-600, solution pH of 5, 0.5 mM of hydrogen peroxide (H2O2) after 30-min ultrasonic power of 296 W, ultrasonic frequency of 50 kHz and ultraviolet wavelength of 302 nm. These findings are crucial for designing Fe-doped TiO2 nanoparticles with high catalytic performance for the degradation of paracetamol and appeared as an alternative solution to treat pharmaceutical compounds effectively.