Degradation Rate Of Methylene Blue Research Articles

PEG mediated NiMn2O4 nanomaterials as a nano catalyst for peroxidase mimetic activity and photocatalytic degradation

Artificial peroxidases have garnered a lot of attention owing to their tremendous superiority over their natural counterparts. Here, NiMn2O4 nanoparticles have been successfully prepared through PEG assisted hydrothermal method. The varied PEG concentrations significantly altered the morphology and particle size of the synthesizedmaterials. We demonstrate the improved peroxide-like assay of different NiMn2O4 nanoparticles for the first time. Among them, Ni4 nanoparticles exhibit good peroxidase-like activity by generating the oxidation of chromogenic substrate 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the presence of H2O2 and a blue color charge transfer product with an absorption maximum is positioned at 652 nm. These observations led to the development of a method for assessingH2O2 that can be read visually and photometrically. The Ni4 nanoparticles show enhanced kinetics compared to the natural enzyme horse radish peroxidase (HRP) with a lower Km (0.168 mM) value. Additionally, this Ni4 nanosphere applies as a visible light photocatalyst for the degradation of methylene blue (MB) and rhodamine B (Rh B) dyes under visible-light irradiation. Under optimized conditions, the degradationrates of MB and Rh B are 68 and 80.7 %, respectively, after 210 min, and recyclable efficiency is about 99 % for Rh B photocatalytic degradation in the first test and 98 % for five cycles, and about 98 % for MB photocatalytic degradation in the first test and 97 % for five cycles.

Novel PWO/ ZnO heterostructured nanocomposites: Synthesis, characterization, and photocatalytic performance

Photocatalytic degradation is becoming an increasingly attractive method for addressing environmental remediation challenges. In this work, the novel pure PWO/ZnO and doped PWO: Er/ZnO: Ag heterostructure nanocomposites with premier photocatalytic efficiency were synthesized via a simple co-precipitation method followed by a solvothermal procedure. X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX), and ultraviolet–visible (UV–Vis) absorbance measurements techniques were employed to characterize the structural and optical properties. HRTEM images prove the possibility of intimate contact formation at the pure and doped PWO/ZnO heterostructure nanocomposite interfaces. The photocatalytic performance of the PWO/ZnO heterostructure nanocomposites in the degradation of the methylene blue (MB) and methyl orange (MO) dyes under UVA light was evaluated. The photocatalysts’ ability in the mineralization of organic pollutants was confirmed by the TOC test. BET and zeta potential analyses were used to study the dye adsorption mechanisms. Additionally, adsorption isotherms and kinetics have been investigated to describe the adsorption of MB and MO into the samples. The degradation rates of MB with PWO/ZnO and PWO: Er/ZnO: Ag heterostructure nanocomposites were 4.7 and 6.6 times higher than those of PWO and PWO: Er nanoparticles. This rate for MO degradation is 5.2 and 3.5 times higher than that of pure PWO and PWO: Er nanoparticles, respectively. This study outlines an easy method to develop innovative, highly effective heterostructure nanocomposites capable of converting UVA light into photocatalytic performance.

Harnessing Evanescent Waves in UV-Irradiated TiO2-Coated Quartz Optical Fibers Improves Pollutant Degradation in Water

Coupling TiO2-coated quartz optical fibers (TiO2-QOFs) with LEDs shows potential in degrading organics in water. Conventional TiO2-QOFs with thick and compact coatings are inefficient to degrade organic pollutants due to refraction losses. The research focuses on manipulating coating strategies to increase the generation of evanescent waves, which react more efficiently with the coated TiO2, which shows a crystal structure at anatase/rutile of 85/15. Through the use of dip-coating methods, TiO2 can be effectively deposited on quartz optical fibers, leveraging the principle of electrostatic attraction. By decreasing TiO2 dip-coating concentrations from 200 to 10 mg/L, dip-coating duration from 2 to 0.5 h, and coating cycles from 3 to 1, TiO2 patchiness on quartz fibers was reduced by 50–60%, enhancing the formation of more interspaces between the fiber surfaces and the coatings, which in turn allowed over 90% of evanescent waves in the TiO2-QOFs. The evanescent wave-dominated TiO2-QOFs irradiated by 275 nm UV-LED exhibited methylene blue degradation rate constants at around 0.03 h−1 and quantum yields greater than unity, indicating a highly efficient interaction between the evanescent wave and the surface coatings. These findings offer significant insights into optimizing the utilization of evanescent waves in TiO2-QOFs for pollutant degradation by regulating the coating structures.

Evaluation of the impact of alkyl silane entity (APTES) on photocatalyst (TiO2) and their photocatalytic degradation of organic compounds for environmental remediation.

Environmental pollution by diverse organic pollutants is a serious issue facing humanity, and the scientific community is working hard to find a solution to climatic change due to pollution. Along the same lines, we have tried to find a material/method which is economical and less laborious for achieving the same desired objectives. In this work, the surface modification of titanium dioxide to be used as a photocatalyst was carried out with different concentrations of alkyl silane agent APTES (3-aminopropyltriethoxysilane) and studied their impact on the degradation of representative compound, i.e., methylene blue. The surface-modified TiO2-APTES nanoparticles were obtained via the solvothermal process. The APTES in different molar (0.21-0.41M) concentrations was obtained by dissolving APTES in ethanol. The obtained samples were characterized through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy, and UV-visible spectroscopy. The photocatalytic activity was inferred from the degradation ability of functionalized nanoparticles for methylene blue and evaluated by UV-visible spectroscopy. Our results demonstrated a significant 70% degradation rate of methylene blue.

Synthesis of porous Mn/Co composite oxides as an efficient peroxymonosulfate activator for removal of methylene blue

Co3O4 has been regarded as a promising heterogeneous catalyst for peroxymonosulfate (PMS) activation to remove organic pollutants. However, its catalytic ability needs to be further improved from a practical point of view. In this work, we prepared porous Mn/Co bimetallic composite oxides as PMS activator via a facile oxalate route. A series of composites with different Mn/Co molar ratios were prepared, and their catalytic performances were comparatively assessed using methylene blue (MB) as the degradation model. The results showed that the catalyst with a Mn/Co molar ratio of 1:2 (Mn1Co2) exhibited optimal MB removal efficiency. More than 90% of MB could be removed within 25 min under the reaction conditions: catalyst dosage of 0.04 g·L−1, PMS concentration of 0.6 mmol·L−1, pH range of 5–9, and reaction temperature of 25 °C. Moreover, •OH, •SO4-, •O2- and 1O2 were identified as reactive oxygen species in the reaction system according to the electron paramagnetic resonance (EPR) results. Besides, it was found that a MB degradation rate over 83% could be maintained after five consecutive recycling runs, indicating the excellent catalytic stability of Mn1Co2. The superb catalytic performance of Mn1Co2 is ascribed to both higher cobalt content and the synergistic effect between Mn and Co. Therefore, it is expected that porous bimetallic Mn1Co2 composite oxides have good application prospects in treating organic dye wastewater.

Photoactive Ce-doped TiO2 and CeO2-TiO2 composite coatings deposited by suspension/solution plasma spray

In this work, Ce-doped TiO2 coatings were produced using a hybrid suspension (SPS) and solution precursor plasma spraying (SPPS) approach. CeO2-TiO2 composite coatings were also deposited by the SPS process. The photocatalytic activity of the coatings was evaluated by measuring the methylene blue degradation rate under visible light. Cerium doping and CeO2 composite coatings were characterized by X-ray diffractometer measurements and verified by energy dispersive spectroscopy mapping, Raman spectra, and X-ray photoelectron spectroscopy analysis. The hybrid SPS/SPPS technique presented a promising method to deposit doped ceramic coatings among thermal spray processes. According to the results, modifying TiO2 coatings decreased the bandgap of TiO2 from 3.25 to 2.3 eV using cerium dopant. However, a lower photocatalytic efficiency of TiO2 -CeO2 composite and Ce-doped TiO2 coatings compared to TiO2 could be related to the lower active surface area of TiO2 covered by submicron CeO2 particles and non-optimal dosage of cerium dopant, respectively.

Dual Functional Si, N-Codoped Carbon Quantum Dots for Selective Fluorescence Sensing of Fe3+ and Visible-Light Photocatalysis of Organic Dyes

This work reports a simple, low cost and eco-friendly one-step hydrothermal method to obtain Si- and N-doped carbon quantum dots (Si-N-CQDs) using only citric acid and (3-aminopropyl) trimethoxysilane. These codoped Si-N-CQDs demonstrated 0D spherical morphology and an average size of [Formula: see text]2.54 nm as well as good solubility in water and high quantum yield equal to 14.3%. Fluorescence emission of these Si-N-CQDs was quenched selectively under the presence of [Formula: see text]. Based on this property, we developed a very sensitive sensor capable of detecting [Formula: see text] up to 400 [Formula: see text]M concentration with a 3.14 [Formula: see text]M detection limit. This sensor was used for [Formula: see text] detection in real tap and lake water and demonstrated satisfactory recovery equal to 102.3–108.0% and 103.5–108.5%, respectively. Photocatalytic activity of our Si-N-CQDs was demonstrated using methylene blue (MB) organic dye. The degradation rate of MB under visible light irradiation increased 2.7 times under the presence of Si-N-CQDs within 60 min. Such excellent performance was attributed to very efficient light absorption of Si-N-CQDs as well as excellent electron transfer and separation of photogenerated charge carriers.

Natural manganese ores for efficient removal of organic pollutants via catalytic peroxymonosulfate‐based advanced oxidation processes

AbstractPeroxymonosulfate‐based advanced oxidation processes (PMS‐AOPs) for in situ persistent organic pollutant (POP) remediation in aqueous solutions can be a promising technology. However, this technology is constrained by its high toxicity and cost of metal oxide and non‐metal catalysts for PMS activation. Here, we investigated the catalytic performance of a widely available natural mineral, manganese ore (MO), for PMS activation. A series of natural MO samples in an aqueous solution were prepared via the Fenton‐like reaction. The samples' crystalline structure, surface morphology, textural properties, and other surface characteristics of the selected MO were systematically characterized. The effects of PMS concentration and process parameters on the degradation performance of four chosen model pollutants, that is, phenol, tetrabromobisphenol A (TBBPA), rhodamine B (RhB), and methylene blue (MB), were evaluated. The experimental results showed that natural MO increased catalytic activity and enhanced the PMS oxidation processes, with 98%, 90%, and 75% removal efficiencies on phenol, TBBPA, and RhB, respectively, within 1.5 h. The reduction in the initial pH solution from 10 to 7 and the increase in temperature from 15 to 45°C enhanced the MB degradation rate (decolorization) by 55 and 46%, respectively, within 2 h. During the PMS activation process, SO4•−, •OH, and 1O2 species were generated, but only SO4•− and •OH radicals with strong oxidative potentials contributed to the catalytic degradation. The dissolved metals from the experiments were found well within the limit of drinking water standards, verifying that the MO + PMS catalytic system is suitable for commercial applications. This work provides insights into the development potential and prospects of using natural minerals for PMS activation and POP degradation, which can accelerate their industrial applications.

Synthesis of cubic Mn2O3 and its catalytic performance in activating peroxymonosulfate for degradation of MB

In this study, uniform Mn2O3 cubic with a size of 0.6–1.1 µm was prepared using a simple carbonate precipitation-calcination method, and its performance in activating peroxymonosulfate (PMS) for degradation of methylene blue (MB) was investigated. A single factor experiment was conducted to investigate the degradation of MB by taking process parameters as variables, such as catalyst amount, PMS dosage, initial MB concentration, reaction temperature and co-existed anions. The results showed that a MB degradation rate of 81.49% was achieved within 50 min under the reaction conditions: Mn2O3 amount of 0.1 g/L, PMS dosage of 0.6 mmol/L, MB concentration of 10 mg/L, a total volume of 500 mL and reaction temperature of 25 °C. In addition, it was found that the introduction of C2O42- or PO43- had a negative effect on MB degradation, with inhibition ratio reaching 33.08% and 17.47%, respectively. However, Cl- had no inhibitory effect on MB degradation. Furthermore, reactive species in the system of Mn2O3/PMS were identified by electron paramagnetic resonance (EPR) tests, and results showed that •OH, SO4•-, •O2– and 1O2 all participated in the MB degradation process. Moreover, Mn2O3 exhibited stable catalytic performance during four consecutive cycling runs, indicating that the as-prepared cubic Mn2O3 is expected to be a potential catalyst for PMS activation and dye wastewater treatment.

Carbon/Mn3O4/SrTiO3 microsphere photocatalyst for the efficient removal of high‐concentration methylene blue from water

AbstractBACKGROUNDWith the development of the textile and dye industry, a large amount of dye wastewater has been discharged. Semiconductor photocatalysis has been widely used in the treatment of environmental pollution, so it is very important to study efficient, nontoxic and stable photocatalysts.RESULTSIn this study, a microspherical activated carbon/Mn3O4/SrTiO3 composite photocatalyst with high catalytic activity was synthesized using sol–gel and chemical precipitation methods. The photocatalyst was characterized through X‐ray diffraction, scanning and transmission electron microscopy, energy dispersive spectroscopy, X‐ray photoelectron spectroscopy, photoluminescence, Electrochemical impedance spectroscopy, electron paramagnetic resonance spectroscopy and photocurrent measurements, and the effects of the initial methylene blue (MB) concentration and pH on the catalytic performance of the photocatalyst were investigated. The results revealed that the MC/Mn3O4/SrTiO3 composite has large light absorbance, and it can effectively inhibit photoinduced electron–hole pair recombination. The catalyst exhibited high photocatalytic degradation activity, and the degradation efficiency of MB at 300 ppm and pH 7 reached 99% after 80 min of UV light irradiation. The photodegradation process conformed to the pseudo‐first‐order kinetic model. Recyclability experiments showed that MC/Mn3O4/SrTiO3 composite has high stability, and the degradation rate of MB is > 70% after three repeat uses.CONCLUSIONSThis work provides a new method for finding low‐cost, high‐performance materials that can be modified and put into industrial use. © 2023 Society of Chemical Industry (SCI).

Preparation, structure and photocatalytic degradation property of a copper-based complex and its derivative material

In order to design a new type of photocatalyst for dye degradation, a novel Cu-based coordination polymer (CP) was prepared by hydrothermal method with a novel bis-pyridine-bis-amide ligand and an aromatic dicarboxylic acid, namely [Cu(3-bbpa)(1,3-BDC)(H2O)]n (Cu-CP, where 3-bbpa ​= ​N1,N4-di(pyridin-3-yl)fumaramide and 1,3-H2BDC ​= ​1,3-benzenedicarboxylic acid). The Cu-CP shown a two-dimensional (2D) layered structure with 10.39 ​Å ​× ​16.31 ​Å cavities, containing one-dimensional (1D) meso-helical [Cu(3-bbpa)]n chain and 1D zigzag [Cu(1,3-BDC)]n chain. The influence of bis-pyridine-bis-amide ligands on the structure of Cu-1,3-BDC-based CPs was discussed. Furthermore, by using the pyrolysis process, the Cu-CP was employed as a catalyst precursor to manufacture a carbon matrix composites (Cu/CuO@C) and was thoroughly described. The results show that both carbon matrix composites have photocatalytic degradability of dyes,the photocatalytic degradation rates of Cu-CP for methylene blue (MB), rhodamine B (RhB), gentian violet (GV), methyl orange (MO) and Congo red (CR) were 35.64%, 82.09%, 87.94%, 70.26%, and 66.71%, respectively. After the characterization of the Cu/CuO@C materials by XPS and solid ultraviolet, it can be seen that they contain metal and its oxide active sites, and the narrow bandgap promotes the rapid transport of photogenerated carriers and increases the photocatalytic degradation rate of five dyes. Therefore, the photocatalytic degradation rate of MB increased to 61.32%, 98.11% for RhB, 93.22% for GV, 72.12% for MO, and 88.36% for CR. According to the quenching studies and electron spin resonance (ESR) spectra characterization, the main species involved in the photocatalytic reaction were the radicals •OH. Cu/CuO@C composites derived from Cu-CP as precursors have been shown to be an efficient photocatalyst material compared to other photocatalysts.

Structure-directing ability of the kraft-lignin/cellulose carbon xerogel for the development of C-Nb2O5 sunlight-active photocatalysts

This work explored the development of C-Nb2O5 materials through the use of kraft lignin/cellulose carbon xerogel as a structure-directing agent in a simple precipitation synthesis pathway. This strategy was based on xerogel’s low-cost and environmentally friendly nature, as well as the lignin's ability to promote structural changes through the chelation of metallic ions and stabilization of crystalline phases. The results showed that the addition of higher quantities of the kraft lignin/cellulose xerogel during the synthesis resulted in the formation of the hexagonal crystalline structure of niobium oxide, whereas the synthesis without the carbonaceous phase led to hexagonal K3NbO2F4 structure. The presence of the carbon xerogel also led to significant morphological changes, such as the formation of rod-like particles with smaller sizes and the augmentation of the specific surface area and pore volume. EDS and XPS show that the hexagonal Nb2O5 obtained was also doped with K and F atoms. The addition of the carbonaceous phase also led to the reduction of the bandgap energy of materials, whereas an increase in the calcination temperature caused a similar bandgap reduction. The material with the highest carbon content (Nb-0.25L) achieved the highest photoresponse under simulated solar light for the simultaneous photodegradation of methylene blue (MB) and photoreduction of Cr (VI), probably due to its lower bandgap energy, higher surface area, and enhanced methylene blue adsorption capacity. The effect of the calcination temperature implied that dye sensitization was an important factor for the Cr (VI) photoreduction, as faster MB degradation rates led to the suppression of Cr (VI) reduction. Finally, the study of the pH effect on the process showed that higher MB adsorption capacities are linked to higher MB removal rates, which coupled with mechanistic evaluation, proves that MB photodegradation is mainly linked to the direct oxidation reaction promoted by photogenerated vacancies.

Nitrogen-doped carbon dot impregnated g-C3N4/SnS2 nanocomposite as an efficient mediator and co-catalyst for enhanced photocatalytic degradation and water splitting

Noble metal electron mediators and co-catalysts have prevented further development of indirect Z-scheme systems for photocatalytic applications. Carbonaceous candidates have been one of the best alternatives to address this issue. For this purpose, in the present study, a novel nitrogen-doped carbon dot (N-DCD) impregnated g-C3N4/SnS2 heterostructure has been successfully synthesized with optimized contents of N-DCDs and SnS2 ultra-thin nanoflakes through thermal-impregnation and reflux methods. The most efficient nanocomposite containing 0.25 wt% N-DCDs and 2 wt% SnS2 exhibited methylene blue (MB) degradation rate constant of 0.032 min−1 and hydrogen (H2) production efficiency of 1622.2 μmol/g.h after 120 and 180 min visible light irradiation. The photodegradation rate constant was almost 32, 8, and 2, and H2 production efficiency was 16, 30, and 5 fold higher than g-C3N4, SnS2, and g-C3N4/2 wt% SnS2 (without N-DCDs), respectively. The photodegradation and H2 production efficiencies are enhanced by impregnated N-DCDs, which act as an electron mediator and noble metal-free co-catalyst. Through N-DCDs impregnation, the synergistic effect between SnS2 and up-conversion properties of N-DCDs was observed, resulting in the reduction of the band gap energy from 2.97 eV in g-C3N4 to 2.80 eV in the optimized ternary nanocomposite, as well as reductions in PL intensity and onset potential. The major active species throughout photocatalytic degradation reactions were superoxide and hydroxyl radicals, proposing a Z-scheme mechanism for charge transfer. The optimized ternary nanocomposite also exhibited outstanding photostability after recycling tests. This work highlighted the role of N-DCDs as a highly effective noble metal-free co-catalyst and electron mediator in photocatalytic applications. Data Availability StatementThe raw/processed data required to reproduce these findings cannot be shared at this time due to legal or ethical reasons.

Enhanced photocatalysis and photohydrophilicity in TiO2–W5O14 nanocomposite thin films grown by in-lay sputtering

Investigation on the photocatalytic and photoinduced hydrophilic properties of pure and nitrogen doped TiO2–W5O14 nanocomposite thin films grown by in-lay sputtering process is reported. For comparison, similar properties of reactively sputtered nanocrystalline titanium dioxide (TiO2) and nanowire tungsten oxide (W18O49) thin films are studied as well. Structurally, TiO2–W5O14 thin films are highly crystalline and strongly multiphased while TiO2 and W18O49 thin films are anatase, monoclinic, respectively. The band gap of nitrogen doped TiO2–W5O14 thin film is ∼2.82 eV while that of TiO2 and W18O49 thin films are ∼3.27 eV. Surface morphology of TiO2–W5O14 and TiO2 films show nanocrystalline particulates of sizes 15–70 nm, 20–50 nm, respectively while W18O49 films show randomly dispersed nanowires with average diameter of ∼50 nm and maximum length of ∼30 μm. Owing to bandgap shift in visible range, porous surface structures and crystallinity, the nitrogen doped TiO2–W5O14 nanocomposite thin films are found to exhibit better (i) photohydrophilicity with water contact angle of ∼7° in 2 h under UV-A irradiation and (ii) photocatalytic efficiency with methylene blue degradation rate of −1.12μmol/(l.d), −0.78 μmol/(l.d) under ultraviolet and visible light sources, respectively.

Kinetics of Catalytic Oxidation of Methylene Blue with La/Cu Co-Doped in Attapulgite

Methylene blue (MB) is a common pollutant in wastewater from the printing and dyeing industries. In this study, attapulgite (ATP) was modified with La3+/Cu2+, using the method of equivolumetric impregnation. The La3+/Cu2+ -ATP nanocomposites were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The catalytic properties of the modified ATP and the original ATP were compared. At the same time, the influence of the reaction temperature, concentration of methylene blue and pH on the reaction rate were investigated. The optimal reaction conditions are as follows: MB concentration is 80 mg/L, the dosage of the catalyst is 0.30 g, the dosage of hydrogen peroxide is 2 mL, the pH is 10 and the reaction temperature is 50 °C. Under these conditions, the degradation rate of MB can reach 98%. The recatalysis experiment was carried out reusing the catalyst, and the experimental results showed that the degradation rate could reach 65% after three uses, indicating that the catalyst could be recycled many times and costs could be reduced. Finally, the degradation mechanism of MB was speculated, and the reaction kinetic equation was obtained as follows: -dc/dt = 14,044 exp(-3598.34/T)C(O)0.28.

Oxygen Vacancies-Rich S-Cheme BiOBr/CdS Heterojunction with Synergetic Effect for Highly Efficient Light Emitting Diode-Driven Pollutants Degradation.

Recently, the use of semiconductor-based photocatalytic technology as an effective way to mitigate the environmental crisis attracted considerable interest. Here, the S-scheme BiOBr/CdS heterojunction with abundant oxygen vacancies (Vo-BiOBr/CdS) was prepared by the solvothermal method using ethylene glycol as a solvent. The photocatalytic activity of the heterojunction was investigated by degrading rhodamine B (RhB) and methylene blue (MB) under 5 W light-emitting diode (LED) light. Notably, the degradation rate of RhB and MB reached 97% and 93% in 60 min, respectively, which were better than that of BiOBr, CdS, and BiOBr/CdS. It was due to the construction of the heterojunction and the introduction of Vo, which facilitated the spatial separation of carriers and enhanced the visible-light harvest. The radical trapping experiment suggested that superoxide radicals (·O2-) acted as the main active species. Based on valence balance spectra, Mott-Schottky(M-S) spectra, and DFT theoretical calculations, the photocatalytic mechanism of the S-scheme heterojunction was proposed. This research provides a novel strategy for designing efficient photocatalysts by constructing S-scheme heterojunctions and introducing oxygen vacancies for solving environmental pollution.

Photoresponsive Activity of the Zn0.94Er0.02Cr0.04O Compound with Hemisphere-like Structure Obtained by Co-Precipitation

In this work, a ZnO hemisphere-like structure co-doped with Er and Cr was obtained by the co-precipitation method for photocatalytic applications. The dopant's effect on the ZnO lattice was investigated using X-ray diffraction, Raman, photoluminescence, UV-Vis and scanning electron microscopy/energy dispersive spectroscopy techniques. The photocatalytic response of the material was analyzed using methylene blue (MB) as the model pollutant under UV irradiation. The wurtzite structure of the Zn0.94Er0.02Cr0.04O compound presented distortions in the lattice due to the difference between the ionic radii of the Cr3+, Er3+ and Zn2+ cations. Oxygen vacancy defects were predominant, and the energy competition of the dopants interfered in the band gap energy of the material. In the photocatalytic test, the MB degradation rate was 42.3%. However, using optimized H2O2 concentration, the dye removal capacity reached 90.1%. Inhibitor tests showed that •OH radicals were the main species involved in MB degradation that occurred without the formation of toxic intermediates, as demonstrated in the ecotoxicity assays in Artemia salina. In short, the co-doping with Er and Cr proved to be an efficient strategy to obtain new materials for environmental remediation.

Degradation of methylene blue by ellipsoidal β-FeOOH@MnO2 core-shell catalyst: Performance and mechanism

An ellipsoidal β-FeOOH@MnO2 core-shell catalyst was synthesized and used to degrade methylene blue (MB). The ultra-thin less-crystalline MnO2 nanosheets loaded on the surface of ellipsoidal β-FeOOH were similar to corn-bracts, and the specific surface area of this catalyst has been significantly improved than β-FeOOH. β-FeOOH@MnO2 exhibited a certain removal rate of MB without peroxymonosulfate (PMS). Then, with the addition of PMS, the degradation rate of MB rapidly increased to 99% after 10 min in β-FeOOH@MnO2/PMS system, which is much higher than that in β-FeOOH/PMS system (51%). LC-MS/MS was used to investigate the degradation products, and a probable degradation pathway was proposed. According to FTIR, XPS and quenching studies, the redox processes of Fe3+/Fe2+ and Mn4+/Mn3+, as well as 1O2, O2−, OH and SO4− produced by catalyst-activated PMS, were found to be primarily responsible for the quick degradation of MB. However, 1O2 plays a key role. Generally, this research indicated that β-FeOOH@MnO2 was an efficient catalyst and had a potential application in practical wastewater treatment.

TiO2‐epoxy nanocomposites coated steel: Surface morphology, spectroscopic, and photocatalytic characteristics

Nanocomposite coatings on metal surfaces provide unique material characteristics that play a strategic role in improving overall product/process quality. Thus, nanocomposite finds applications in different sectors such as petroleum, automobile, electrical and electronics, chemical, medical, metallurgy, food packaging, and air purification. This study focused on the fabrication of TiO2‐epoxy nanocomposites for coating on steel sheet and analyzing their properties. The nanocomposites were prepared at 2%, 4%, and 8% (w/w) TiO2 particle loading content. Different coated sheets were analyzed for surface morphology, spectroscopic, and photocatalytic characteristics. Field emission scanning electron microscope (FESEM) images showed uniform particle distribution of TiO2 in the epoxy matrix at a lower concentration. Besides, TiO2 nanoparticle cluster sizes ranged from 79.6 to 172 nm, 79.5 to 237 nm, and 122 to 164 nm for the samples of 2%, 4%, and 8% TiO2 content, respectively. The Ti weight percent significantly increased from 1.69% to 7.34% with the rise in the level of TiO2 filler in the TiO2‐epoxy matrix, whereas O content varies from 22.07% to 26.02%. A characteristic absorption peak of TiO2 at nearly 700 cm−1 in all the Fourier‐transform infrared (FTIR) spectra of samples was detected. Degradation of methylene blue (MB) in the photocatalytic (UV‐C + TiO2) process was significantly higher than photolysis (UV‐C) in a photoreactor. The degradation rate of MB increased with treatment time and TiO2 loading content in the samples. Besides, after 1 h of treatment, maximal degradation of MB was 1.58% for photolysis whereas 1.96%, 2.63%, and 3.51% for the coated sheet of 2%, 4%, and 8% TiO2, respectively. Overall, the superior quality of steel sheets was obtained when coated with TiO2‐epoxy nanocomposites.

Green synthesis of copper oxide nanoparticles using Ephedra Alata plant extract and a study of their antifungal, antibacterial activity and photocatalytic performance under sunlight

In the present work, copper oxide (CuO NPs) was synthesized by an eco-friendly, simple, low-cost, and economical synthesis method using Ephedra Alata aqueous plant extract as a reducing and capping agent. The biosynthesized CuO-NPs were compared with chemically obtained CuO-NPs to investigate the effect of the preparation method on the structural, optical, morphological, antibacterial, antifungal, and photocatalytic properties under solar irradiation. The CuO NPs were characterized using X-ray diffraction (XRD), UV-VIS spectroscopy, Fourier transform infrared spectrometer (FTIR) analysis, and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDX). The photocatalytic activities of biosynthetic CuO-NPs and chemically prepared CuO-NPs were studied using methylene blue upon exposure to solar irradiation. The results showed that the biosynthesized CuO photocatalyst was more efficient than the chemically synthesized CuO-NPs for Methylene Blue (MB) degradation under solar irradiation, with MB degradation rates of 93.4% and 80.2%, respectively. In addition, antibacterial and antifungal activities were evaluated. The disk diffusion technique was used to test the biosynthesized CuO-NPs against gram-negative bacteria, Staphylococcus aureus and Bacillus subtilis, as well as C. Albicans and S. cerevisiae. The biosynthesized CuO-NPs showed efficient antibacterial and antifungal activity. The obtained results revealed that the biosynthesized CuO-NPs can play a vital role in the destruction of pathogenic bacteria, the degradation of dyes, and the activity of antifungal agents in the bioremediation of industrial and domestic waste.