Main Oxidative Species Research Articles

Sono-photocatalytic degradation of tetracycline and pharmaceutical wastewater using WO3/CNT heterojunction nanocomposite under US and visible light irradiations: A novel hybrid system

In this paper, in-situ fabrication of tungsten oxide (WO3) on carbon nano-tube (CNT) was performed via sol-gel/hydrothermal method to prepare WO3/CNT nanocomposites and then coupled with visible light and ultrasound (US) irradiations for sono-photocatalytic removal of tetracycline (TTC) and pharmaceutical wastewater treatment. The as-prepared catalysts were characterized by FT-IR, XRD, TEM, UV-VIS DRS, FESEM, EDS, TGA, BET, BJH, EIS, and EDX techniques. The characterization tests, indicated successful incorporation of CTNs into the WO3 framework and efficient reduction of charge carries recombination rate after modifying with CNT. The investigation of experimental parameters verified that 60 mg/L TTC could be perfectly degraded at optimum operational parameters (WO3/CNT: 0.7 g/L, pH: 9.0, US power: 250 W/m2, and light intensity: 120 W/m2 over 60 min treatment. Trapping experiments results verified that HO radicals and h+ were the main oxidative species in degradation of TTC. The as-prepared photocatalysts could be reused after six successive cycles with an approximately 8.8 % reduction in removal efficiency. Investigation of the effect of real pharmaceutical wastewater revealed that this system is able to eliminate 83.7 and 90.6 % of TOC and COD, respectively after 220 min of reaction time. Some compounds with lower toxic impact and molecular weight, compared to raw pharmaceutical wastewater, were detected after treatment by sono-photocatalysis process. The biodegradability of real pharmaceutical wastewater was improved significantly after treatment by WO3/CNT sono-photocatalysis.

Effectively enhanced photodegradation of Bisphenol A by in-situ g-C3N4-Zn/Bi2WO6 heterojunctions and mechanism study.

In our work, a series of in-situ g-C3N4-Zn/Bi2WO6 heterojunctions were synthesized by a two-step solvothermal method followed with calcination process, using dicyanamide as the precursor for g-C3N4. C3N4-Zn/BWO heterojunctions were of gossypine shape, and both C3N4 and Zn were finely distributed into BWO nanosheets, forming a hierarchical structure. C3N4-Zn/BWO with 2.0g of precursor addition and calcined at 520°C exhibited effectively enhanced photodegradation for typical organic contaminant BPA, degrading 93% within 120min, and implied a maximum rate constant k of 0.0211 min-1, indicating synergistic effect of C3N4 and Zn components in C3N4-Zn/BWO heterojunction. The enhancement of photocatalysis was due to quick carriers' separations via Z-scheme system and enlarged specific surface area of as-synthesized C3N4-Zn/BWO heterojunction. Main reactive oxidation species were detected to be h+ and O2-, and nine intermediates were confirmed via anlysis of LC-MS/MS. This study provided an alternative strategy to design novel photocatalysts containing multicomponents for higher photocatalytic activity.

Highly efficient catalytic degradation of p-nitrophenol by Mn3O4.CuO nanocomposite as a heterogeneous fenton-like catalyst

In this work, nano-sized mixed oxides of Mn3O4 and CuO were successfully prepared by a simple hydrothermal method and used as an effective heterogeneous sono-Fenton catalyst for p-nitrophenol (PNP) degradation at the neutral condition. The prepared nanocomposite was characterised by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and N2 adsorption–desorption analysis. The results showed that the Mn3O4.CuO nanocomposite can catalyze efficiently the decomposition of PNP under ultrasonic irradiation in comparison with pristine Mn3O4 and CuO. The almost complete degradation of PNP was achieved within 20 min at pH 8.0 by using 0.1 mol/L of H2O2 and 0.01 g of the catalyst. Also, the stability and reusability test showed that the prepared nanocomposite had good stability during the Fenton process. Finally, the main oxidative species involved in the sono-Fenton process based on the results of radical species trapping experiments were identified.

An effective strategy for boosting photoinduced charge separation of Ag3PO4 by BiVO4 with enhanced visible light photodegradation efficiency for levofloxacin and methylene blue.

In this paper, a Z-scheme Ag3PO4/BiVO4 photocatalyst was successfully prepared by precipitation-deposition method. The Ag3PO4/BiVO4 composite exhibited enhanced photocatalytic activity and recyclability for levofloxacin and methylene blue degradation under visible light irradiation. In the Ag3PO4/BiVO4-0.4 system, up to 92.44% of the levofloxacin molecules can be decomposed within 180min and the photocatalytic degradation efficiency can maintain at 92.02% for methylene blue after recycled for 5 times. The enhanced photocatalytic activity of Ag3PO4/BiVO4 heterojunctions could be mainly attributed to the fabrication of hetero-structure between BiVO4 and Ag3PO4. The photogenerated electron-hole pair separation was effectively enhanced based on the photocurrent, electro-chemical impedance spectra and photoluminescence data. Furthermore, the electrons transfer from photoinduced BiVO4 to Ag3PO4 and the visible light harvesting efficiencies were significantly increased due to the BiVO4 hybridization. The ·OH was the main oxidative species in the Ag3PO4/BiVO4 system for the methylene blue decomposition. Finally, a purposed photocatalytic mechanism for methylene blue degradation was discussed in detail on the basis of experimental results.

Application of a stable Ag/TiO2 film in the simultaneous photodegradation of hormones

AbstractBACKGROUNDThe natural hormones estrone (E1) and 17β‐estradiol (E2) and the synthetic hormone 17α‐ethynylestradiol (EE2) are excreted daily by humans and may reach water and wastewater treatment plants, which do not efficiently remove these estrogens. The aim of the present study was to evaluate the efficiency and reusability of Ag/TiO2 films as catalysts for simultaneous degradation of the hormones E1, E2 and EE2 in aqueous medium by heterogeneous photocatalysis and the contribution of reactive oxygenated species. The influence of aeration on the system and the effects of estrogen concentration and Ag/TiO2 film area were also evaluated in the photodegradation process.RESULTSThe photocatalytic degradation assays showed efficiency higher than 97% for E2 and EE2 (10 μg L−1) after approximately 3.5 h and above 95% for E1 (100 μg L−1) after 4.5 h. It was observed that hydroxyl radical is the main reactive oxidant species in the photodegradation process, responsible for 87, 86 and 79% degradation of E1, E2 and EE2 respectively.CONCLUSIONThe treatment process applied using the Ag/TiO2 films proved to be very stable and efficient for the simultaneous degradation of the studied hormones up to 305 h of reaction period, obtaining a percentage of degradation above 90%. © 2019 Society of Chemical Industry

A charcoal-shaped catalyst NiFe2O4/Fe2O3 in electro-Fenton: high activity, wide pH range and catalytic mechanism

ABSTRACT A charcoal-shaped catalyst NiFe2O4/Fe2O3 in electro-Fenton (EF) was synthesized by a facile precipitation approach via sintering products of oxalate co-precipitation. This obtained NiFe2O4/Fe2O3 catalyst was easily separated via an external magnetic field and was used as a heterogeneous electro-Fenton catalyst for rhodamine B (RhB, a target pollutant) degradation. Characteristics of NiFe2O4/Fe2O3 catalyst were assessed using scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Barrett-Emmett-Teller (BET), respectively. SEM results revealed that the proposed NiFe2O4/Fe2O3 was charcoal-shaped with the size in the range of 0.5–5 μm. Experiment results show that the EF process with the proposed catalyst could work in a wide pH range from 3 to 9. Under optimized conditions, estimated 90% RhB degradation was achieved in 60 min under the following conditions: 0.6 g/L NiFe2O4/Fe2O3, pH 3. Radical scavengers and electron spin resonance (ESR) spectra results demonstrated that the main oxidant species involved was , accounting for RhB degradation in EF. Moreover, according to our research on interfacial reaction, was mainly generated from the homogenous Fenton reaction rather than the surface Fenton reaction, stimulating by the dissolved Fe2+, Fe3+ and Ni2+ from catalyst. The reusability of NiFe2O4/Fe2O3 catalyst was evaluated for recycling the same catalyst for 5 runs. In conclusion, the facile fabrication NiFe2O4/Fe2O3 catalyst shows great potential in wastewater treatment with promising activity.

One-step synthesis of phosphorus/oxygen co-doped g-C3N4/anatase TiO2 Z-scheme photocatalyst for significantly enhanced visible-light photocatalysis degradation of enrofloxacin

Anatase TiO2 nanoparticles coated with P and O co-doped g-C3N4 were prepared via a single-step procedure. The resulting POCN/anatase TiO2 demonstrated remarkable performance in the degradation of enrofloxacin (ENFX). The photocatalytic activity of this heterojunction was 28.9 and 3.71 times better than that of the CN and anatase TiO2, respectively. The microtopography of the POCN/anatase TiO2 was revealed in this study. Co-doping with P and O increased the visible light adsorption capacity of the g-C3N4, whereas the anatase TiO2 nanoparticles enhanced the adsorption properties of the ENFX and the separation of the photoinduced carriers of the POCN/anatase TiO2. The O2·− and h+ were the main reactive oxidative species in the photocatalytic degradation of ENFX. The results of the detection of H2O2 and ESR confirmed that POCN/anatase TiO2 was a type Z-scheme photocatalyst. Finally, the ENFX degradation pathways were estimated through the detection of by-products.

Fe-based metal-organic frameworks as Fenton-like catalysts for highly efficient degradation of tetracycline hydrochloride over a wide pH range: Acceleration of Fe(II)/ Fe(III) cycle under visible light irradiation

In this work, a series of Fe-based metal-organic frameworks (Fe-MOFs) were synthesized and served as Fenton-like catalysts for tetracycline hydrochloride (TC–HCl) degradation. Herein, for the first time, we have demonstrated that visible light can accelerate Fe(II)/Fe(III) cycle in the photo-Fenton system based on iron-oxo (Fe-O) clusters in frameworks. Among these Fe-MOFs, MIL-101 possessed the highest activity mainly ascribed to its largest specific surface area and pore volume, and the most coordinatively unsaturated iron sites. The synergistic effect in the MIL-101/H2O2/visible light system was derived from the efficient separation and migration of photogenerated carriers. Due to the function of solid acid catalysts, MIL-101 extended effective pH range up to 10.2 and exhibited good reusability and stability. Hydroxyl radicals generated from H2O2 coordinated at iron active sites were determined as the main reactive oxidative species and acceleration of Fe(II)/Fe(III) cycle was responsible for highly effective degradation of TC–HCl.

Photodegradation of organic pollutants in wastewater with different morphologies of silver phosphate nanocatalysts

Photocatalyst can use the sunlight to photodegrade the environmental pollutants. In this article, AgNO3 and Na2HPO4 were used as raw materials to prepare different morphology Ag3PO4 nanocatalyst with different methods. They are solid phase method, hydrothermal method, conversion precipitation method and direct precipitation method. Four kinds of photocatalysts are donated as Ag3PO4-GX, Ag3PO4-SR, Ag3PO4-ZJ and Ag3PO4-ZH, respectively. The obtained materials were characterized by XRD, UV-VIS DRS, SEM and BET.XRD analyse results showed that the Ag3PO4 prepared by four methods have good crystallinity form sharp diffraction peak. UV-VIS DRS results showed that the band gap of four samples are 1.66 eV (Ag3PO4-GX), 1.91eV (Ag3PO4-ZJ), 2.13 eV (Ag3PO4-ZH) and 3.37 eV (Ag3PO4-SR), respectively. SEM results showed that the samples prepared by direct precipitation method and hydrothermal method make Ag3PO4 particles more uniform and the samples have better morphology, more porous and uniform distribution of particles. The surface area of the samples prepared by the four methods is in the range of 20-35 m2/g. The photocatalytic capacity of four Ag3PO4 were investigates by methyl orange, methyl blue and ofloxacin. The photodegradation experiment showed that the Ag3PO4 photocatalyst prepared by direct precipitation method exhibited best degradation efficiency under the visible light irradiation. The mechanism of the remarkable photocatalysis was also explored by determining the role of active radicals. The results showed that h+ was the main active oxidation species in the presence of aerobic degradation of levofloxacin, while ⋅OH active species had little effect on the degradation of pollutants.

Rapid and template-free synthesis of copper(I) oxide-graphitic carbon nitride heterojunction for photocatalytic degradation of orange II dye in water

Herein, we report the synthesis of a p-n heterojunction catalyst comprising Cu2O and g-C3N4 via a novel rapid, template-free and facile one-pot approach. The pristine semiconductors and their composite were characterised by X-ray diffraction (XRD), N2 adsorption-desorption isotherms (BET), UV–vis diffuse reflectance spectroscopy, transmission electron microscopy (TEM), field emission scanning electronic microscopy (FESEM) and energy dispersive X-ray spectrometry (EDX). From the Mott-schottky plot, the flat-band potential and carrier density were estimated. Band gap energies of 2.03 and 2.65 eV were calculated for Cu2O and g-C3N4 respectively, which indicate that both catalysts possess excellent optical absorption in the visible region of the solar spectrum. The p-n heterojunction produced a type-II band alignment which promotes the efficient separation of photogenerated electron-hole pairs. The photocatalytic property of the material was evaluated by employing it for the degradation of orange II dye in water. Different mass ratios of Cu2O-g-C3N4 such as 1:1, 3:2, 7:3 and 9:1 were employed in the degradation process. However, Cu2O-g-C3N4 with mass ratio 9:1 displayed the best photocatalytic performance, giving a removal efficiency that is 3.6 times higher than the pristine Cu2O. The decolourisation and mineralisation efficiencies were 85% and 60% after 4 h of treatment. Scavenger studies further revealed the photogenerated holes as the main oxidant species in the photocatalytic reaction.

Highly efficient photodegradation of various organic pollutants in water: Rational structural design of photocatalyst via thiol-ene click reaction

It is of great importance to control the structure of titanium dioxide (TiO2)-based photocatalysts for the elimination of organic pollutants in water. The intrinsic highly efficient and ubiquitously employed click reaction is currently underutilized by environmental scientists. In this paper, we report the use of thiol-ene click reaction for the facile preparation of TiO2-bacterial cellulose (BC) composite using two chemically functionalized precursors, i.e. thiol-functionalized uniform TiO2 nanoparticles of different sizes and vinyl-functionalized bacterial cellulose. Results from the electron spin resonance experiments showed that one could easily increase the number of main oxidative species, i.e. OH radicals, of the BC/TiO2 composite by using smaller TiO2 nanoparticles and further nitrogen doping, exhibiting higher photocatalytic reactivity. Consequently, our photocatalysts with well structural control have demonstrated remarkably higher reactivity for the degradation of various organic molecules than many previously reported TiO2-based photocatalysts. With more virtues of excellent reusability and stability, our sample has shown its great potential for the removal of organic molecules in real polluted water. Our work has also presented a novel methodology for the design of inorganic/organic composite materials with readily tunable structure and composition since our protocol could be easily applied to other systems.

A rapid and efficient removal approach for degradation of metformin in pharmaceutical wastewater using electro-Fenton process; optimization by response surface methodology.

Presence of emerging contaminants such as pharmaceutical products in aquatic environments has received high concern due to their undesirable effect on wildlife and human health. Current work deals with developing a treatment model based on the electro- Fenton (EF) process for efficient removal of metformin (MET) from an aqueous medium. The obtained experimental results revealed that over the reaction time of 10 min and solution pH of 3, the maximum removal efficiency of 98.57% is achieved where the value of MET initial concentration, current density, and H2O2 dosage is set at 10 mg.L-1, 6 mA.cm-2, and 250 μL.L-1, respectively, which is in satisfactory agreement with the predicted removal efficiency of 98.6% with the desirability of 0.99. The presence of radical scavengers throughout the mineralization of MET under the EF process revealed that the generation of •OH radicals, as the main oxidative species, controlled the degradation mechanism. The obtained kinetics data best fitted to the first order kinetic model with the rate constant of 0.4224 min-1 (R2 = 0.9940). The developed treatment process under response surface methodology (RSM) was employed for modeling the obtained experimental data and successfully applied for efficient removal of the MET contaminant from pharmaceutical wastewater as an adequate and cost-effective approach.

Three-dimensional electro-Fenton system with iron foam as particle electrode for folic acid wastewater pretreatment

At the very first time, a three-dimensional (3D) iron foam was used as the particle electrode for folic acid (FA) wastewater pretreatment in the electro-Fenton (EF) process. In this work, the effects of key operating parameters, including the initial COD concentration, applied current, initial pH and iron foam dosage were optimized regarding the chemical oxygen demand (COD) and total nitrogen (TN). COD and TN removal percentage of FA wastewater reached 43.5% and 70.4%, respectively during 6 h electrolysis under the following optimal conditions: initial COD concentration of 10,000 mg/L, applied current of 300 mA, initial pH of 3 and iron foam dosage of 4 g. Regarding the main oxidant species in the proposed EF with iron foam particle electrode, OH and active chlorine were responsible for FA mineralization, confirming by the electron paramagnetic resonance (EPR) spectra of DMPO−OH. The kinetic analysis and mechanism study suggested that both electro-oxidation and electro-coagulation exited in the system. A possible FA degradation pathway based on the identification of by-products was proposed according to Liquid chromatography/time-of-flight/mass spectrometry results. In addition, BOD5/COD ratio improved from 0.22 to 0.44 after EF treatment coupled with toxicity reduction. In a word, EF with iron foam particle electrode was a feasible process for FA pretreatment.

A novel nano-sized MoS2 decorated Bi2O3 heterojunction with enhanced photocatalytic performance for methylene blue and tetracycline degradation

In this paper, MoS 2 was used as a band-suitable semiconductor to construct the Bi 2 O 3 /MoS 2 heterostructured photocatalysts for the first time via a deposition-hydrothermal method. The XRD, SEM and HRTEM analysis indicated that the surface of Bi 2 O 3 was decorated with MoS 2 nanoparticles and Bi 2 O 3 /MoS 2 heterojunctions were formed. The performances on photocatalytic degradation of methylene blue (MB) and tetracycline (TC) were evaluated under visible light irradiation. The results demonstrated that the Bi 2 O 3 /MoS 2 heterojunctions displayed remarkably improved photocatalytic activity for both MB and TC degradation, compared to the base material (Bi 2 O 3 ). Specifically, as the molar ratio of MoS 2 was 23.81%, the obtained Bi 2 O 3 /MoS 2 -23.81 heterojunctions exhibited promising photocatalytic activities, and approximately 100% MB and 97% TC were degraded within 100 min, respectively. The superior photocatalytic activity was mainly attributed to its large surface area, high visible-light harvesting and the efficient separation of photogenerated electrons and holes caused by the unique heterojunction architecture. Notably, the Bi 2 O 3 /MoS 2 heterojunctions showed remarkable stability in recycling photocatatlytic experiments. The active species trapping and terephthalic acid (TA) fluorescence experiments indicated that the •OH was the major reactive oxidizing species for MB degradation. Furthermore, the intermediates were detected by UPLC-MS spectrometry and the possible degradation pathways for MB and TC were proposed. Finally, a possible reaction mechanism of Bi 2 O 3 /MoS 2 heterojunctions for the photodegradation MB was also proposed. This interesting interfacial architecture strategy will provide useful insights for designing and fabricating new class of binary heterojunctions with high-efficient photocatalytic activity towards practical application. A highly efficient visible-light responsive photocatalyst Bi 2 O 3 /MoS 2 heterojunctions was prepared for the organic dyes and antibiotic pollutants elimination. • Bi 2 O 3 /MoS 2 heterojunction was prepared by deposition-hydrothermal method. • Bi 2 O 3 /MoS 2 -23.81 exhibited enhanced photocatalytic activity than that of pure Bi 2 O 3 . • The electrons transfer and visible-light harvesting effects were obviously improved. • The ⋅OH was the main oxidative species of Bi 2 O 3 /MoS 2 -23.81 for the MB decomposition.

Facile fabrication of Ag–Bi2GeO5 microflowers and the high photodegradable performance on RhB

In this work, a simple template-free one-pot solvothermal method was used to prepare hierarchical microflowers from Ag-modified Bi2GeO5 nanosheets. To characterize the phases and morphologies of the products, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area measurements were used. The characterization results showed the deposition of some spherical metal Ag particles ranging from 10 to 20 nm in size on the Bi2GeO5 nanosheets surface and the nanosheets-assembly of hierarchical microflowers with macroporous structures. Based on the Ag nanoparticles surface plasmonic resonance (SPR) and the hierarchical microflowers structure of Bi2GeO5, the Ag-modified Bi2GeO5 self-assembly microflowers exhibited excellent UV-light absorption. Photodegradable tests indicated that the decolorization rate of RhB with Ag-modified Bi2GeO5 (RN = 0.1) microflowers was nearly 100% within 25 min, which was 1.5 times higher compared to that of unmodified Bi2GeO5 microflowers. Additionally, the photocatalytic performance stability tests demonstrated that the Ag-modified Bi2GeO5 hierarchical microflowers has excellent chemical stability. Investigations into the main oxidative species indicate that the main active species of Ag-modified Bi2GeO5 in RhB photodegradation are the superoxide radical ( $${\text{O}}_{2}^{ \cdot - }$$ ), and the ·OH and h+ are also partially involved in the photocatalytic process. Finally, a possible photocatalytic mechanism for RhB photo-degradation onto Ag-modified Bi2GeO5 microflowers was proposed.

Novel magnetically separable of Fe3O4/Ag3PO4@WO3 nanocomposites for enhanced photocatalytic and antibacterial activity against Staphylococcus aureus (S. aureus)

BackgroundIron oxide nanocomposites have received a great attention for their application in various fields like physics, medicine, biology, and material science etc., due to their unique properties, such as magnetism, electrical properties, small size, biocompatibility and low toxicity.MethodsFe3O4/Ag3PO4@WO3 nanocomposites with different weight percent of Ag3PO4 were successfully prepared through fabricated Ag3PO4/Fe3O4 with WO3 via in situ fabrication method, electrospinning involved precursor solution preparation and spinning to enhance photocatalyst performance under simulated sunlight for the degradation of methylene blue (MB) and antibacterial activity against Staphylococcus aureus (S. aureus).ResultsThe photocatalytic degradation of methylene blue (MB) under simulated light irradiation indicated that the nanocomposite with 0.25 mg of Ag3PO4 has the best activity. An additional advantage of these photocatalysts is magnetic recoverability, using external magnetic field and photocatalytic stability of the nanocomposites was evaluated for three cycles. In addition, using different scavengers, holes (h+) and superoxide radical (O2·−) radicals and hydroxide radical (·OH) were identified the main oxidative species in the degradation reaction of methylene blue.ConclusionsThe results reveal that Fe3O4/Ag3PO4@WO3-0.25 nanocomposites have photocatalytic and antibacterial activity against S. aureus. The photocatalyst and mechanism based on the enhancement of electron transfer processes between Ag3PO4 and WO3 nanoparticles.

Degradation of Phenol Using Peroxymonosulfate Activated by a High Efficiency and Stable CoMgAl-LDH Catalyst.

In this study, we report on an active and stable CoMgAl layered double hydrotalcite (LDH) catalyst for phenol degradation by heterogeneous activation of peroxymonosulfate (PMS). The CoMgAl-LDH catalyst was synthesized by hydrothermal method. The PMS/CoMgAl-LDH system overcomes the drawbacks of traditional Fenton processes. Various effects, e.g., scavengers, chloride ion, catalyst dosage, PMS concentration, temperature, and pH, were also inspected to evaluate the system. The results indicated that the PMS/CoMgAl-LDH system had extremely high efficiency for phenol degradation; 0.1 mM phenol could be completely degraded by 0.3 g/L catalyst and 3 mM PMS within 60 min at 30 °C. The CoMgAl-LDH catalyst appeared to possess outstanding reusability and stability. After four rounds of recycling, nearly 100% of the phenol was removed within 80 min by the PMS/CoMgAl-LDH system, with only 0.05 mg/L Co2+ leaching. A sulfate radical was the main oxidation species in the PMS/Co-LDH system. The degradation rate of phenol was influenced by temperature, and the activation energy was 65.19 kJ/mol. These advantages proved the PMS/CoMgAl-LDH system is an effective strategy for the treatment of organic contaminants.

Synthesis and photocatalytic properties of BiOI/NiFe2O4 composites

BiOI/NiFe2O4 composite is a novel type of photocatalyst, which has good photocatalytic activity and magnetic property. In this paper, BiOI/NiFe2O4 composites with different molar ratios were synthesized by hydrothermal approach. The as-prepared samples were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM) and UV–vis diffuse reflectance (UV–vis DRS) to study the crystalline structures, morphologies and optical properties. The photocatalytic performance of BiOI/NiFe2O4 composites were investigated through the experiments of photocatalytic degradation of methyl orange (MO), and the results showed that the photocatalytic activity of 20% BiOI/NiFe2O4 was the highest. It was worth mentioning that the recovery of the used composites can be performed easily owing to the good magnetic property. Terephthalic acid photoluminescence (TA-PL) probing and trapping agent experiments demonstrated that photogenerated hole h+ was the main active oxidation species and played a major role, while ·OH and played secondary roles during the photocatalytic process.

Synthesis of PPy-ZnO composite used as photocatalyst for the degradation of diclofenac under simulated solar irradiation

A composite photocatalyst consisting of polypyrrole (PPy) and zinc oxide (ZnO) was successfully synthesized via a polymerization method. Different characterization techniques confirmed that ZnO was intimately attached on PPy. The photocatalytic activity of PPy-ZnO composite was studied experimentally for the degradation of diclofenac (DCF) under simulated solar light irradiation at ambient conditions. It was indicated that the photocatalytic rate constant of PPy-ZnO was nearly 2 times higher than that of ZnO. Through tests with scavengers, h+ was shown to be the main oxidative species responsible for the degradation of DCF by PPy-ZnO, resulting in 81% degradation of the molecule in merely 60 min.

Constructing magnetic Pt-loaded BiFeO3 nanocomposite for boosted visible light photocatalytic and antibacterial activities.

Visible light-responsive Pt-loaded coral-like BiFeO3 (Pt-BFO) nanocomposite at different Pt loadings was synthesized via a two-step hydrothermal synthesis method. The as-synthesized photocatalyst was characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and magnetic hysteresis loop (M-H loop) analyses. The FESEM images revealed that Pt nanoparticles were evenly distributed on the coral-like BFO. The UV-vis DRS results indicated that the addition of Pt dopant modified the optical properties of the BFO. The as-synthesized Pt-BFO nanocomposite was effectively applied for the photodegradation of malachite green (MG) dye under visible light irradiation. Specifically, 0.5wt% Pt-BFO nanocomposite presented boosted photocatalytic performance than those of the pure BFO and commercial TiO2. Such a remarkably improved photoactivity could be mainly attributed to the formation of good interface between Pt and BFO, which not only boosted the separation efficiency of charge carriers but also possessed great redox ability for significant photocatalytic reaction. Moreover, the strong magnetic property of the Pt-BFO nanocomposite was helpful in the particle separation along with its great recyclability. The radical scavenger test indicated that hole (h+), hydroxyl (·OH) radical, and hydrogen peroxide (H2O2) were the main oxidative species for the Pt-BFO photodegradation of MG. Finally, the Pt-BFO nanocomposite was revealed high antibacterial activity towards Bacillus cereus (B. cereus) and Escherichia coli (E. coli) microorganisms, highlighting its potential photocatalytic and antibacterial properties at different industrial and biomedical applications.