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1.
J Colloid Interface Sci ; 607(Pt 1): 269-280, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34506999

RESUMO

Tetragonal/orthorhombic-bismuth tungstate (t/o-Bi2WO6) homojunctions of high photocatalytic efficiencies were fabricated through a novel in situ Bi induced phase transformation. The photocatalytic efficiencies of t-Bi2WO6 were greatly enhanced via formation of the homojunction. Photocatalytic degradation of rhodamine B (RhB), a recalcitrant organic pollutant, under simulated sunlight illumination was investigated as a demonstration for the efficiency enhancement. A 6.22 folds improvement was achieved with formation of the homojunction in terms of reaction rate constants. The homojunction catalyst was demonstrated to be photocatalytically stable over a five cycles operation. The t/o-Bi2WO6 homojunction enhances separation and utilization efficiency of photo-generated charge carriers and thus greatly boosts the catalytic efficiency. Trapping tests and electron spin resonance spectroscopy were conducted to reveal that singlet oxygen (1O2), hole (h+), electrons (e-), and superoxide anion radical (O2-) are the main working reactive species for RhB degradation. Density functional theory (DFT) calculations were performed to prove the feasibility of Bi induced phase transformation of t-Bi2WO6 to o-Bi2WO6. The present development offers a new design route for high efficiency photocatalysts for water pollution control.


Assuntos
Poluentes Ambientais , Compostos de Tungstênio , Bismuto , Luz
2.
J Colloid Interface Sci ; 607(Pt 1): 423-430, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34509116

RESUMO

For semiconductor-based photocatalytic reactions, defect engineering has been proven as an efficient approach to enhance the photocatalytic performance. In this work, a synergistically PVP/EG-assisted in situ self-assembly strategy has been successfully developed for preparing flowerlike BiOCl nanospheres (NSP) assembled by ultrathin nanosheets (thickness of 3.8 nm) with abundant oxygen vacancies (OVs). During the hydrothermal process, PVP plays a template role in controlling the orientation of the crystallite growth, leading to the forming of nanosheets. Meanwhlie, ethylene glycol would induce the self-assembly of nanosheets into a loose hierarchical architecture duo to its stereo-hindrance effect. NSP achieves a twice higher photocatalytic conversion of benzylamine than BiOCl nanosheets (NST) under visible light. XPS, ESR, NH3-TPD results manifest that NSP possesses more active sites including OVs and unsaturated Bi atoms than NST, because of avoiding the accumulation of ultrathin nanosheets. In situ FTIR reveals that benzylamine molecules can be chemisorbed and activated on BiOCl interfaces via forming -N…Bi- species. The OVs can facilitate the forming of superoxide radicals (•O2-), achieving the selective photooxidation. Finally, a possible synergetic mechanism based on the interaction of reactants and catalyst interfaces was proposed to illustrate the photocatalytic process at the molecular level.


Assuntos
Bismuto , Nanosferas , Catálise , Luz , Oxigênio
3.
J Colloid Interface Sci ; 607(Pt 1): 568-583, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34509732

RESUMO

This work investigates the effects of double ion substitution on the ferroelectric, electrochemical, dielectric and photocatalytic properties of Gd and Fe doped La1-yGdyNi1-xFexO3 nanoparticles (NPs). La1-yGdyNi1-xFexO3 was fabricated by facile micro-emulsion path and its properties were studied by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman scattering, Fourier Transform of Infrared (FTIR), energy dispersive x-rays (EDX) techniques. It has a distorted rhombohedral shape with crystallite size within the range of 17-23 nm. The doped material has a spherical heterogeneous morphology, and its surface area increased with increased doping. The electrochemical (CV, EIS, and I-V), conductivity and dielectric (dielectric constant and low dielectric & tangent loss) properties of La1-yGdyNi1-xFexO3 were dependent on the contents of the dopants (Gd and Fe). The doped material had improved specific capacitance compared to the undoped LaNiO3 due to the synergistic effect of Gd and Fe on the doped materials. The conductivity of Gd and Fe doped LaNiO3 5.16 × 104 Sm-1 was enhanced compared to the undoped LaNiO3 3.52 × 10-2 Sm1. Furthermore, hysteresis loop was used to investigate the coercivity (Hc), saturation magnetization (Ms) and remanence (Mr) of the material. The Ms and Mr values were enhanced with the content of the dopants. The photocatalytic activity (PCA) of the material in degrading malachite green (MG) dye was studied. La1-yGdyNi1-xFexO3 NPs was able to degrade up to 96.4% of the dye under visible light irradiation in 50 min. La1-yGdyNi1-xFexO3 has remarkable dielectric, electrochemical, ferroelectric and photo-catalytic properties and have potential applications in microwave, electrical, electronic, energy storage devices. It is also an active photo-catalyst material for the removal/oxidation of toxic pollutants from the environment.


Assuntos
Luz , Corantes de Rosanilina , Catálise , Difração de Raios X
4.
J Colloid Interface Sci ; 607(Pt 1): 595-606, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34509734

RESUMO

In this work, a Z-scheme heterojunction of BiOIO3/MIL-88B was constructed via two steps solvothermal method. Various characterization techniques showed that this Z-scheme heterojunction is an effective strategy to promote spatial charge separation, and the catalytic performance was evaluated by degrading simulated organic pollutants. Herein, the BiOIO3/MIL-88B composites exhibited an exceptional removal rate for Reactive Blue 19 and tetracycline hydrochloride (TC) under visible light irradiation, which was approximately 3.28 and 4.22 times higher than the pristine BiOIO3, respectively. Additionally, the analysis of photocatalysis mechanism showed that the active species O2- and OH could strongly affect the degradation of tetracycline hydrochloride (TC) in the studied system. Furthermore, the degradation process of TC was tracked and detected by identifying intermediates produced in the reaction system. It is anticipated that this research can deepen the understanding of BiOIO3/MIL-88B heterojunction structure to remove organic contaminants and provide a strategy for applying photocatalytic technology in the practical industry.


Assuntos
Poluentes Ambientais , Catálise , Luz , Dietilamida do Ácido Lisérgico/análogos & derivados , Tetraciclina
5.
J Colloid Interface Sci ; 607(Pt 1): 607-620, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34520904

RESUMO

A photocatalytic process was used to effectively remove glyphosate, an emerging pollutant and contaminant, through advanced oxidation. For this purpose, a feasible combination strategy of two-step anodisation and electrodeposition methods were proposed to fabricate graphene quantum dots (GQDs) supported titanium dioxide nanotube arrays (TNAs). The resultant GQDs/TNAs heterojunction composite exhibited significant degradation reactivity and circulation stability for glyphosate due to its excellent photo-generated electron and hole separation ability. After the introduction of GQDs into TNAs, the photodegradation efficiency of glyphosate increased from 69.5% to 94.7% within 60 min under UV-Vis light irradiation (λ = 320-780 nm). By analysing the intermediate products and through the evolvement of heteroatoms during glyphosate photodegradation, alanine and serine were discovered for the first time, and a detailed degradation mechanism of glyphosate was proposed. This study indicates that GQDs/TNAs heterojunction composite can almost completely degrade the glyphosate into inorganics under the appropriate conditions.


Assuntos
Grafite , Nanotubos , Pontos Quânticos , Catálise , Glicina/análogos & derivados , Luz , Titânio
6.
Chemosphere ; 286(Pt 2): 131726, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34343921

RESUMO

Metal-organic frameworks (MOFs) have been investigated recently as effective visible light photocatalysts. In this report, we synthesized nickel, iron, and titanium-based MOFs with different oxidation states of metal ions and aminoterephthalic acid ligand for photocatalytic degradation of Rhodamine B (RhB) dye under solar light irradiation. The photoluminescence analysis revealed that the Fe-MOF could suppress the recombination of photoinduced charges and effectively degrade the dye. The photocatalytic experiment demonstrated that the Fe-MOF exhibited higher degradation efficiency of dye (90 %) compared to the Ni-MOF (9 %) and Ti-MOF (50 %) at pH 7 in 90 min. In addition, the effects of catalyst amount, dye concentration, and solution pH on dye degradation were investigated. The photodegradation of dye using Fe-MOF was well-fitted to the first-order kinetics with an R2 value of 0.9987. Furthermore, reactive oxygen species test and electron paramagnetic resonance study revealed that the superoxide anion radicals were mainly responsible for the dye degradation. Cyclic test analysis indicates that there was no substantial decrease in the degradation efficiency of dye after four consecutive cycles.


Assuntos
Estruturas Metalorgânicas , Catálise , Ligantes , Luz , Rodaminas
7.
Chemosphere ; 286(Pt 2): 131737, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34352551

RESUMO

Recently, graphitic carbon nitride (g-C3N4) has received significant attention as a non-metallic, visible-light-activated photocatalyst for treating water and wastewater by degrading contaminants. Accordingly, previous review articles have focused on the photocatalytic properties of g-C3N4-based materials. However, g-C3N4 has several other notable features, such as high adsorption affinity towards aromatic substances and heavy metals, high thermal and chemical resistances, good compatibility with various materials, and easily scalable synthesis; therefore, in addition to simple photocatalysis, it can be widely used in other decontamination systems based on activation of oxidants and electrocatalysis. This critical review provides a comprehensive summary of recent advancements in g-C3N4-based materials and their use in treating polluted water and wastewater via the following routes (1) activation of oxidizing agents (e.g., hydrogen peroxide, ozone, peroxymonosulfate, and persulfate): and (2) photoelectrocatalysis using fabricated g-C3N4-based photocathodes and photoanodes. For each route, we briefly summarize the primary mechanisms, distinctive features, and performances of various water treatment systems using g-C3N4-based catalysts. We also highlight the specific roles of g-C3N4 in improving the efficiencies of these treatment processes. The advantages and limitations of previously reported water treatment systems using g-C3N4-based materials are also described and compared in this review. Finally, we discuss the challenges and prospects of improving g-C3N4-based water purification applications.


Assuntos
Águas Residuárias , Purificação da Água , Catálise , Luz , Oxidantes
8.
Chemosphere ; 286(Pt 2): 131783, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34364228

RESUMO

Two-dimensional (2D) bismuth-based semiconductors have aroused intensive concern owing to their prominent photocatalytic activity for organic pollutants removal. In this work, a facile strategy for introducing oxygen vacancy in Bi-based oxyiodides (BixOyIz) sheet-like architectures to activate molecular oxygen was proposed. The structure, photoelectric properties and visible light (λ > 420 nm) induced photocatalytic activities of these samples for decomposition of bisphenol A (BPA) were systematically characterized and evaluated. The as-prepared Bi7O9I3 with a feeding Bi/I molar ratio of 1:1 exhibited the best photocatalytic activity comparable to those of similarly synthesized Bi7O9I3 with other molar ratios and BiOIO3 catalysts. The optimal Bi7O9I3 achieved excellent photocatalytic activity with 99.6 % degradation efficiency of BPA within 20 min and superior structural stability with 95.1 % degradation retention over 5 cycling tests. In addition, the resulting Bi7O9I3 sample displayed a high mineralization efficiency of BPA. Importantly, the plenty of oxygen vacancies (Vos) exsiting in Bi7O9I3 played the dominant role in both accelerating electron transfer and activating molecular oxygen to facilitate the generation of superoxide radical (O2·-) and singlet oxygen (1O2), thereby proceeding oxidative degradation of BPA molecules during photoreactions. The efforts and attempts are also extendable to synthesis other 2D photocatalysts, providing potential for effective charge-carrier separation and molecular oxygen activation.


Assuntos
Compostos Benzidrílicos , Oxigênio , Bismuto , Iodetos , Luz , Óxidos , Fenóis
9.
Chemosphere ; 286(Pt 2): 131848, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34388867

RESUMO

Methylene blue is a dye that is extensively used in the textile industry but it is a hazardous, carcinogenic, and mutagenic pollutant. Therefore, the treatment of wastewater containing methylene blue by photocatalytic degradation under visible light without using any sacrificial agent (H2O2) is an important method towards attaining an eco-friendly environment. Herein, the nanocomposite of Ag-doped TiO2 on WO3 nanoparticles (Ag@TiO2/WO3) was prepared by a modified sol-gel precipitation route, and their physicochemical properties were studied. The bandgap of Ag sensitized metal oxide nanocomposite in Ag@TiO2/WO3 was slightly reduced compared to the pristine titania due to the creation of interstitial energy states during colligation of titania and tungsten oxide. The ease of charge carrier transfers through the heterojunction of TiO2/WO3 increased the photocatalytic activity of the photocatalyst. Furthermore, in Ag@TiO2/WO3 the plasmonic Ag sensitization to the host semiconductor TiO2 has further boosted the rate of photocatalytic degradation because of the surface plasmon resonance (SPR) and hindrance of charge carrier recombination. Due to the synergistic effect of SPR and the presence of heterojunction in Ag@TiO2/WO3, the photocatalytic activity was found to be 25 times higher for Ag@TiO2/WO3 than that of commercial DP25 photocatalyst under visible light towards methylene blue degradation.


Assuntos
Peróxido de Hidrogênio , Azul de Metileno , Luz , Titânio
10.
Chemosphere ; 286(Pt 3): 131906, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34416590

RESUMO

In this study, g-C3N4 with a high portion of tri-s-triazine groups was synthesized to activate peroxymonosulfate (PMS) under visible light irradiation, termed as Vis/g-C3N4/PMS process, to degrade one frequently detected recalcitrant micropollutant carbamazepine (CBZ). The Vis/g-C3N4/PMS process increased pseudo first-order degradation rate constant of CBZ by 2 times compared with that in the absence of PMS. The enhanced CBZ degradation was because of the production of HO and SO4- from the PMS activation, but not the enhanced charge separation of g-C3N4 due to the presence of PMS. The Vis/g-C3N4/PMS process is insensitive to dissolved oxygen, chloride and bicarbonate concentrations, effective over a wide pH range from 6.0 to 10.0, and less affected by high concentrations of natural organic matter compared with the UV/chlorine and UV/TiO2 processes. In addition, photocatalytic activity of g-C3N4 remains stable over 5-cycle of reuse. These features make the process practically relevant and implementable in degrading micropollutants in drinking water, treated wastewater, surface water, groundwater, etc., using more efficient visible light LEDs or even sunlight.


Assuntos
Luz , Peróxidos , Carbamazepina , Águas Residuárias
11.
J Sci Food Agric ; 102(1): 299-311, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34091912

RESUMO

BACKGROUND: Stevia rebaudiana is a high value crop due to the strong commercial demand for its metabolites (steviol glycosides) but has limited geographical cultivation range. In non-native environments with different daylength and light quality, Stevia has low germination rates and early flowering resulting in lower biomass and poor yield of the desired metabolites. In this study, artificial lighting with light-emitting diodes (LEDs) was used to determine if different light quality within and outside of the photosynthetically active radiation (PAR) range can be used to improve germination rates and yields for production of steviol glycosides for the herbal supplement and food industry. RESULTS: Plants treated with red and blue light at an intensity of 130 µmol m-2  s-1 supplemented with 5% of UV-A light under a 16-h photoperiod produced the most desirable overall results with a high rate of germination, low percentage of early flowering, and high yields of dry leaf, stevioside and rebaudioside A, 175 days after planting. CONCLUSION: While red and blue light combinations are effective for plant growth, the use of supplemental non-PAR irradiation of UV-A wavelength significantly and desirably delayed flowering, enhanced germination, biomass, rebaudioside A and stevioside yields, while supplemental green light improved yield of biomass and rebaudioside A, but not stevioside. Overall, the combination of red, blue and UV-A light resulted in the best overall productivity for Stevia rebaudiana. © 2021 Society of Chemical Industry.


Assuntos
Flores/crescimento & desenvolvimento , Fotossíntese/efeitos da radiação , Sementes/efeitos da radiação , Stevia/crescimento & desenvolvimento , Biomassa , Diterpenos do Tipo Caurano/metabolismo , Flores/química , Flores/efeitos dos fármacos , Flores/metabolismo , Germinação , Glucosídeos/metabolismo , Luz , Sementes/química , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Stevia/química , Stevia/metabolismo , Stevia/efeitos da radiação
12.
Chemosphere ; 287(Pt 4): 132347, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34582929

RESUMO

The decomposition of water pollutants including industrial dyes and chemicals via photocatalytic decontamination is one of the major investigated problems in recent years. Two-dimensional molybdenum disulfide (MoS2) layers have shown great promise as an efficient visible-light photocatalyst owing to its numerous active sites and large surface area. In this study, atomically thin MoS2 films of different thicknesses from monolayer to five-layer and ten layers were fabricated on sapphire substrates using chemical vapor deposition (CVD). We demonstrate that these MoS2 thin films can be used as a photocatalyst to degrade Methylene Blue (MB) dye and can be recovered completely with utmost structural and chemical stability. Under visible-light irradiation, the MB absorption peak completely disappears with ∼95.6% of degradation after 120 min. We also demonstrate the reusability of the MoS2 thin films without significantly losing the photocatalytic activity even after 5-cycles of degradation studies. The chemical and structural stability of the MoS2 films after 5-cycles of degradation studies were affirmed using various spectroscopic studies. Our findings suggest that the MB degradation efficiency increases from 19.01% to 98.46% with an increase in pH from 4 to 14. Our approach may facilitate a further design of other transition metal dichalcogenides-based recoverable photocatalysts for industrial applications.


Assuntos
Luz , Molibdênio , Catálise , Corantes
13.
Chemosphere ; 287(Pt 4): 132380, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34600002

RESUMO

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.


Assuntos
Antibacterianos , Nanocompostos , Catálise , Luz , Tetraciclina , Tetraciclinas
14.
Chemosphere ; 287(Pt 4): 132298, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34610539

RESUMO

In recent years, the piezophotocatalytic mechanism had been intensively recognized as a potential and promising route to sewage treatment. Here we report the piezoelectric effect improved heterogeneous photocatalysis of g-C3N4/Ag/ZnO (g-CN/A/Z) tricomponent in rhodomine B (RhB) degradation. Initially, the nanomaterials were characterized for their physico-chemical and optoelectronic properties using analytical techniques such as x-ray diffraction (XRD), scanning & transmission electron microscopes (SEM & TEM), UV-vis spectrophotometer and photoluminescence spectroscopy (PL). In addition, the photoelectrochemical activity of determining the photocurrent density and electrochemical impendence response were also been conducted. The catalytic properties of the tricomponent, g-CN/A/Z was studied with the degradation of RhB with visible photons irradiation and ultrasonication. In piezophotocatalysis, degradation up to 89% of RhB was achieved with 1.26 folds synergetic effect on par to the photocatalysis and piezocatalysis.


Assuntos
Óxido de Zinco , Catálise , Luz , Difração de Raios X
15.
Appl Ergon ; 99: 103618, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34775135

RESUMO

It is well known that exposure to light at the right time of the day is important to synchronise our circadian rhythm and enhance cognitive functioning. There is, however, a lack of field studies investigating which lighting characteristics are necessary to improve sleep and cognitive functioning. A controlled field study with 80 shift workers was set up, in which the impact of an integrative lighting (IL) scenario was investigated during the morning shift. Two groups were compared: a control group (no change in lighting settings) and a IL-group (exposed to a melanopic Equivalent Daylight Illuminance of 192 lux, i.e., bright light with a high fraction of short-wavelengths). Pre-post measurement of visual comfort, cognitive functioning (D2 task, go-nogo reaction time task) and sleep (MotionWatch8) were performed. The IL-settings ameliorated sleep efficiency and sleep latency during morning shift and enhanced alertness (not inhibition) compared to standard lighting conditions. Changing lighting settings in an industrial setting should be considered as it seems worthwhile for employees' sleep and cognitive performance.


Assuntos
Iluminação , Melatonina , Atenção , Ritmo Circadiano , Cognição , Humanos , Luz , Sono
16.
Chemosphere ; 287(Pt 2): 132174, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34826902

RESUMO

Removal of the hazardous and endocrine-disrupting 2,4-dichlorophenol (2,4-DCP) from water bodies is crucial to maintain the sanctity of the ecosystem. As a low bandgap material (1.37 eV), NaBiS2 was hydrothermally prepared and used as a potential photocatalyst to degrade 2,4-DCP under visible light irradiation. NaBiS2 appeared to be highly stable and remained structurally undeterred despite thermal variations. With a surface area of 6.69 m2/g, NaBiS2 has enough surface-active sites to adsorb the reactive molecules and exhibit a significant photocatalytic activity. In alkaline pH, the adsorption of 2,4-DCP on NaBiS2 appeared to decrease whereas, the acidic and neutral environments favoured the degradation. An increase in the photocatalyst dosage enhanced the degradation efficiency from 81 to 86 %, because of higher vacant adsorbent sites and the electrostatic attraction between NaBiS2 and 2,4-DCP. The dominant scavengers degraded 2,4-DCP by forming a coordination bond between chlorine's lone pair of electrons and the vacant orbitals of bismuth, following the order hole> OH > singlet oxygen. Being non-toxic to both natural and aquatic systems, NaBiS2 exhibits antifungal properties at higher concentrations. Finally, the electron-rich NaBiS2 is an excellent electrocatalyst that effectively degrades organic pollutants and is a promising material for industrial and environmental applications.


Assuntos
Anti-Infecciosos , Ecossistema , Catálise , Clorofenóis , Cinética , Luz , Fotólise
17.
Chemosphere ; 287(Pt 2): 132238, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34826927

RESUMO

Magnetic binary heterojunctions are a kind of promising photocatalysts due to their high catalytic activity and easy magnetic separation; however, their synthesis may involve high costs or secondary environmental impacts. In this work, the magnetically recyclable Mn0.6Zn0.4Fe2O4@Zn1-xMnxS (MZFO@Zn1-xMnxS, x = 0.00-0.07) photocatalysts are synthesized from spent batteries via a green biocheaching and egg white-assisted hydrothermal method. The as-synthesized photocatalysts have been comprehensively characterized in phase, morphology, texture, optics, photoelectrochemistry and photocatalytic activity. Characterization results indicate that the desired core-shell structure MZFO@Zn1-xMnxS composites are successfully synthesized, theirs absorption intensity in the visible light region is greatly enhanced compared to Zn1-xMnxS. In addition, doped Mn2+ in ZnS host lattice and the staggered bandgap alignment of MZFO and Zn1-xMnxS greatly enhances electron transfer and charge separation in the binary heterojunction system. The optimized MZFO@Zn0.95Mn0.05S shows the highest photodegradation performance toward phenol under the visible light irradiation, with a complete degradation of 25 mg L-1 of phenol within 120 min, and its reactive kinetic constants is about 5.2 and 13.3 times higher than that of pure Zn0.95Mn0.05S and MZFO, respectively. Furthermore, the mechanism and pathways for the degradation of phenol are proposed. In addition, MZFO@Zn0.95Mn0.05S also exhibits a good reusability and high magnetic separation properties after 5 successive cycles. This new material has the advantages of low costs, simple reuse and great potential in application.


Assuntos
Luz , Fenol , Catálise , Fenóis , Zinco
18.
Chemosphere ; 287(Pt 3): 132283, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34826942

RESUMO

The present investigation demonstrates an enhancement of the visible photocatalytic activities by C ion implantation in ZnO nanorod arrays (NRAs). Vertically aligned ZnO NRAs were prepared by seed layer assisted solution-phase growth and implanted with 70 keV carbon ions at various fluencies: 1E15, 5E15, 1E16, and 3E16 ions/cm2. X-ray diffraction and FESEM results revealed the crystalline 1D ZnO NRAs having a length of ∼3 µm with a diameter in the range of 150-200 nm. C implantation induces the absorption towards the visible region and a substantial decrease in the optical bandgap energy from 3.2 eV to 2.43 eV. The photocatalytic activities (PC) of C ion-implanted ZnO NRAs were investigated through the degradation of 4-Nitrophenol (4-NP) and methylene blue dye (MB) under ambient visible light irradiation. The degradation efficiency of C ion-implanted ZnO NRAs increases compared to the pristine ZnO NRAs from 60.12% to 93.7% and 48.6 to 97.5% for MB and 4-NP, respectively. The synergistic effects of low energy carbon ion-induced bulk and surface interface electronic states facilitate a narrow band of visible light absorption and efficient charge separation to increase the visible-light-driven photocatalytic performance of ZnO NRAs.


Assuntos
Azul de Metileno , Óxido de Zinco , Carbono , Catálise , Íons , Luz , Nitrofenóis
19.
Chemosphere ; 287(Pt 1): 131984, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34438206

RESUMO

Modification and bandgap engineering are proposed to be extremely significant in improving the photocatalytic activity of novel photocatalysts. The current research focused on the fabrication of ultrafast and efficient visible light-responsive ternary photocatalyst containing g-C3N4 nanostructures in conjugation with polypyrrole doped carbon black (PPy-C) and gold (Au) nanoparticles by highly effectual, simple, and straightforward methodology. Various analytical techniques like XRD, FESEM, TEM, XPS, FTIR, and UV-Vis spectroscopy were applied for characterization purposes. The XRD and XPS results confirmed the successful creation of a nanocomposite framework among Au, PPy-C and g-C3N4. The TEM images revealed that bare g-C3N4 holds sheets or layered graphitic structure with sizes ranging from 100 to 300 nm. The sponge-like PPy-C network intermingled perfectly with g-C3N4 sheets along with homogeneously distributed 5-15 nm Au nanoparticles. The band gap energy (Eg) for bare g-C3N4, PPy-C/g-C3N4 and Au@PPy-C/g-C3N4 nanocomposites were found to be 2.74, 2.68, and 2.60 eV, respectively. The photocatalytic activity for all newly designed photocatalysts have been assessed during the degradation of insecticide Imidacloprid and methylene blue (MB) dye, where Au@PPy-C/C3N4 was found to be extremely efficient with ultrafast removal of both imidacloprid and MB in just 25 min of visible light irradiation. It was revealed that the Au@PPy-C/g-C3N4 ternary photocatalyst removed 96.0% of target analyte imidacloprid, which is ⁓ 2.91 times more efficient than bare g-C3N4 in treating imidacloprid. This report provides a distinctly promising, highly effectual and straightforward route to destruct extremely toxic and notorious pollutants and opens a new gateway in the present challenging scenario of environmental concerns.


Assuntos
Nanopartículas Metálicas , Nanocompostos , Catálise , Ouro , Luz , Polímeros , Pirróis , Fuligem
20.
Chemosphere ; 287(Pt 1): 132072, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34481174

RESUMO

High-performance photocatalytic applications require to develop heterostructures between two semiconductors with matched band energy levels to facilitate charge-carrier separation. The S-scheme photocatalytic system has great potential to be explored, in terms of the improvement of charge separation, however, small efforts have been made in photocatalytic disinfection application. In this study, a non-toxic and low-cost S-scheme photocatalytic system composed of α-Fe2O3 and g-C3N4 was fabricated by in-suit production of g-C3N4 and firstly applied into water disinfection. The α-Fe2O3/g-C3N4 junction demonstrated an enhanced activity for photocatalytic bacterial inactivation, with the complete inactivation of 7 log10 cfu·mL-1 of Escherichia coli K-12 cells within 120 min under visible light irradiation. Its logarithmic bacterial inactivation efficiency was nearly 7 times better than that of single g-C3N4. The experimental results suggested that the effective prevention of charge-carrier recombination led to an improved generation of reactive oxygen species (ROSs), resulting in impressive disinfection performance. Moreover, the DNA gel electrophoresis experiments validated the reason for the irreversible death of bacteria, which was the leakage and destruction of chromosomal DNA. In addition, this S-scheme heterojunction also showed excellent photocatalytic disinfection performance in authentic water matrices (including tap water, secondary treated sewage effluent, and surface water) under visible light irradiation. Hence, the α-Fe2O3/g-C3N4 composite has great potential for sustainable and efficient photocatalytic disinfection applications.


Assuntos
Desinfecção , Escherichia coli K12 , Antibacterianos , Catálise , Luz
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