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Zinc Oxide Nanoparticles Synthesized by Suaeda japonica Makino and Their Photocatalytic Degradation of Methylene Blue
摘要： Green chemistry gained special attention for the environmental safety. In addition, green synthesized plant based nanoparticles for the degradation of industrial pollutant dye also received special focuses. Thus, photocatalytic activity of nanosized zinc oxide (Sj-ZnONps) synthesized by a simple co-precipitation method using sodium hydroxide, zinc nitrate, and Suaeda japonica extract as starting materials was carried out. The reaction was implemented in comparatively low temperature (50oC) without further calcination. The absorption spectrum demonstrated an extinction peak at ~362 nm, which is characteristic to the ZnO nanoparticles. Field-emission transmission electron microscope revealed smaller agglomeration of hexagonal Sj-ZnONps (~100 nm). X-ray diffraction patterns exposed polycrystalline ZnO with hexagonal wurtzite structure. The self-assembly of Sj-ZnONps was achieved due to the capping of phytoconstituents present in extract as evident from Fourier-transform infrared spectroscopy analysis. The photocatalytic degradation of Sj-ZnONps was estimated in reduction of methylene blue (MB). The reaction mixtures comprising of MB, S. japonica extract and Sj-ZnONps had the most significant decrease of MB by 54 %. In conclusion, the Sj-ZnONps can be used as a photocatalyst for decomposition of organic pollutions present in water.
关键词： Photocatalytic degradation,Green synthesis,Suaeda japonica Makino,Methylene blue,Zinc oxide nanoparticles
更新于2025-09-23 15:21:21
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Preparation of porous graphene/carbon nanotube composite and adsorption mechanism of methylene blue
摘要： The graphene oxide (GO) and modified carbon nanotubes (MCNTs) were dispersed in water and mixed with toluene to form homogeneous emulsion, then the porous graphene–carbon nanotubes composites (MCG) were prepared through hydrothermal reaction. The adsorption mechanism of MCG was investigated by adsorption methylene blue. The morphology of MCG was analyzed by scanning electron microscope and transmission electron microscopy. It was found that MCG had rich micropore structures and MCNTs were interlaced on graphene sheets. The pore size of MCG can be effectively controlled by changing the volume ratio of toluene to the GO/MCNTs solution in the emulsion. MCG was characterized by X-ray diffractometer, Raman spectrometer, X ray photoelectric instrument and other analytical instruments. It was found that MCG had more oxygen functional groups. The experimental results show that kinetics can be well-described by pseudo-second-order model. The smaller the pore size, the higher the equilibrium adsorption capacity and the slower the adsorption rate. The adsorption thermodynamic parameters show that the adsorption process is spontaneous and belongs to physical adsorption, and high temperature is beneficial to adsorption. The fitting results of MCG-5 equilibrium adsorption data are matched with the Langmuir model and the saturated adsorption capacity is 232 mg g?1. After five cycles of adsorption–desorption operation, the adsorption capacity of MCG-5 decreases slightly.
关键词： Thermodynamics,Graphene,Methylene blue,Carbon nanotubes,Kinetics
更新于2025-09-23 15:21:01
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Immobilization of C/Ce-codoped ZnO nanoparticles on multi-walled carbon nanotubes for enhancing their photocatalytic activity
摘要： C/Ce-codoped ZnO nanoparticles immobilized onto multi-walled carbon nanotubes (C/Ce-ZnO@MWCNT) were successfully fabricated via the hydrothermal method for degradation of methylene blue (MB) under visible light irradiation. The prepared C/Ce-ZnO@MWCNT samples were characterized by XRD, XPS, FTIR, FE-SEM, EDX, BET, and diffuse reflectance spectroscopy. The obtained results indicated that the photocatalytic activity of all the MWCNTs-containing samples was higher than those of the bare ZnO and C/Ce-codoped ZnO nanoparticles. Besides, the C/Ce-ZnO@MWCNT composite with 50 wt% MWCNT showed the highest photocatalytic activity with the MB removal efficiency of 96.5% recorded within 90 min under visible light illumination using 1.0 g/L catalyst dosage at pH of 9 and MB concentration of 30 ppm. The degradation mechanism controlled by the charge transfer process in C/Ce-ZnO@MWCNT composite was proposed and discussed in detail. In addition, the long-term-use ability of the photocatalyst was also evaluated through experiments conducted in continuous cycles.
关键词： visible light,C/Ce-ZnO@MWCNT,photocatalytic activity,multi-walled carbon nanotube,methylene blue
更新于2025-09-23 15:19:57
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Controlled Engineering Nano-sized FeOOH@ZnO Hetero-Structures on Reduced Graphene Oxide for Lithium ion Storage and Photo-Fenton Reaction
摘要： In this work, a nano-sized goethite and zinc oxide hetero-structure (FeOOH@ZnO) dispersed on reduced graphene oxide (RGO) sheets to construct a ternary composite (FeOOH@ZnO/RGO) is first synthesized by a stepped graphene oxide (GO) deoxygenation process. Ferrous ion (Fe2+) and metal Zn were employed as reducing agents, which were transformed to corresponding FeOOH and ZnO nanoparticles to form a hetero-structure in the reaction. Particularly, the size of the nanoparticles can be controlled by limiting the growth kinetics in this work. As a result, porous RGO architecture is constructed with well-dispersed hetero-structured nanoparticles constituted by FeOOH and ZnO nano-crystals encapsulated. The FeOOH@ZnO/RGO composite exhibits unique lithium ion storage properties as anode for lithium ion batteries. And compared with the binary FeOOH/RGO and ZnO/RGO composites, the ternary FeOOH@ZnO/RGO composite shows the best battery performance as anode for lithium ion batteries and the best photo-Fenton degradation activity toward methylene blue (MB) degradation under simulated sunlight irradiation. The preparation route for FeOOH@ZnO/RGO composite is straightforward, effective and has great potential to be scaled-up.
关键词： zinc oxide,goethite,graphene,methylene blue degradation,photo-Fenton,lithium ion batteries
更新于2025-09-23 15:19:57
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A New Ag/AgBr/LaAlO3 Plasmonic Composite: Synthesis, Characterization, and Visible-Light Driven Photocatalytic Activity
摘要： In recent years, fabricating the visible-light induced photocatalysts based on the concept of plasmonic photocatalysis provides an efficient way to reduce environmental pollution. Accordingly, the present investigation has been carried out to develop such materials based on lanthanum aluminate (LaAlO3; LAO) and Ag/AgBr. The Ag/AgBr/LAO composite is prepared by deposition of metallic Ag nanoparticles onto the pre-prepared AgBr/LAO heterostructure by visible-light photo-reduction. The characteristic properties of synthesized catalysts were investigated by using a variety of techniques such as XRD, N2 adsorption–desorption, FESEM/EDX/EDS mapping, TEM-HRTEM, UV–Vis DRS, FT-IR, XPS, and PL measurements. The photocatalytic degradation of methylene blue (MB) was used as a probe reaction to evaluate their photocatalytic activity under visible-light irradiation. Because of the higher surface area with vast mesoporous nature, enhanced visible light absorption, and more efficient charge separation after the deposition of Ag/AgBr, the composite Ag/AgBr/LAO showed enhanced photocatalytic activity compared with pristine LAO. The recycling experiment revealed excellent stability (up to five successive cycles) of Ag/AgBr/LAO composite. Furthermore, a photocatalytic mechanism is proposed for the degradation of MB over Ag/AgBr/LAO composite. The composite Ag/AgBr/LAO can be used as a promising catalyst for environmental remediation.
关键词： charge separation,methylene blue,Ag/AgBr,plasmonic Ag nanoparticles,nanocomposite,LaAlO3
更新于2025-09-23 15:19:57
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Nitrogen-doped graphene-cerium oxide (NG-CeO <sub/>2</sub> ) photocatalyst for the photodegradation of methylene blue in waste water
摘要： This study shows a facile approach for the preparation of CeO2 nanoparticles decorated with porous nitrogen-doped graphene (NG) nanosheets for effective photocatalytic degradation of methylene blue (MB). NG nanosheets were first synthesized using a hydrothermal method and then nitrogen-doped graphene-cerium oxide (NG-CeO2) was prepared through mixing of cerium nitrate with different concentrations of NG under ultrasonication followed by hydrothermal treatment. The synthesized nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The photocatalytic activity of the synthesized nanocomposites was analyzed against MB dye. Results showed that the nanocomposites of NG-CeO2 have an average particle size of 20 nm. The as-prepared NG-CeO2 nanocomposites exhibited outstanding photocatalytic activity for dye degradation under visible light irradiation, which could be attributed to synergistic effects between the NG nanosheets and CeO2. The quantum of photodegradation increases with the increase of the NG content in the nanocomposites.
关键词： nitrogen-doped graphene,CeO2,methylene blue,photodegradation
更新于2025-09-23 15:19:57
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Lifetime-weighted photoacoustic imaging
摘要： Photoacoustic (PA) imaging has been utilized to quantify the lifetime profile of exogenous agents using a series of pump-probe pulses with a varying time delay; however, current techniques typically lead to long acquisition times which are sensitive to motion and cause absorption or photobleaching. We introduce a technique called lifetime-weighted imaging, which uses only three laser pulses to preferentially weight signals from chromophores with long lifetimes (including exogenous contrast agents with triplet excited states such as methylene blue and porphyrins) while nulling chromophores with short picosecond- to nanosecond-scale lifetimes (including hemoglobin). This technique detects the PA signal from a probe pulse either with or without a pump pulse. By subtracting the probe-only signal from the pump-present probe signal, we effectively eliminate signals from chromophores with short lifetimes while preserving PA signals from chromophores with long-lifetimes. We demonstrate the oxygen-dependent lifetime of both methylene blue and porphyrin-lipids and demonstrate both ground-state recovery and excited-state lifetime-weighted imaging. Lifetime-weighted PA imaging may have applications in many molecular imaging application including: photodynamic therapy dosimetry guidance and oxygen sensing.
关键词： methylene blue,lifetime-weighted,photoacoustic microscopy,porhpyrins,lifetime
更新于2025-09-23 15:19:57
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Purification of Methylene Blue via Photocatalytic Nanofibrous Membranes Containing TiO <sub/>2</sub> Nanoparticles
摘要： In this paper, titanium dioxide nanoparticles were synthesized and deposited on polyacrylonitrile nanofiber membranes via a sol-gel process. Filter structure consisted of a non-woven polyurethane-carbon substrate, polyacrylonitrile nanofiber and titanium dioxide nanoparticles. The concentration of methylene blue dye solution was measured via UV radiation. The filtration efficiency was calculated via Langmuir-Hinshelwood pseudo-first order equations. The results showed that the filtration efficiency of samples using titanium dioxide under UV rays was higher than those without titanium dioxide and UV rays in both immersing and cross-flow processes. Degradation efficiency of the cross-flow system was three times higher than that of immersing method. In the cross-flow process, the effect of three variables- pressure on the membrane, initial concentration of dye solution and pH of the dye solution was studied under UV rays. The highest efficiency obtained was 90.3% by using 1.5 bar pressure, 40 μM initial concentration and pH of 4.1.
关键词： catalysts,fibers,methylene blue,degradation,textiles,membranes
更新于2025-09-19 17:15:36
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Раrаdохical Sесоndаrу Emissiоn Mаss Sресtrum оf thе Lеuсо Fоrm оf Mеthуlеnе Bluе
摘要： A paradoxical relation between the secondary emission mass spectra of Methylene Blue and its leuco form is revealed: in the mass spectrum of the dye cation Cat+ (oxidized form with the molecular weight 284), an intense product of its reduction with m/z 285 is recorded, while the mass spectrum of the leuco dye (reduced form with the molecular weight 285) corresponds to an oxidized form with a dominating peak at m/z 284. An explanation of this empirical fact is proposed: the redox reactions induced by ionizing factors under the conditions of secondary emission experiments pass in the direction permitted for the particular initial form of the redox-active compound. Namely, an oxidized form undergoes reduction, whereas the reduced form is oxidized. This effect should be taken into account for the correct identification of redox-active compounds by their secondary emission mass spectra and for simulating redox reactions in the systems containing redox-active dyes under mass spectrometric conditions.
关键词： leuco form,Methylene Blue cationic dye,secondary emission mass spectrometry,redox reactions
更新于2025-09-19 17:15:36
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Construction of 1D Ag-AgBr/AlOOH Plasmonic Photocatalyst for Degradation of Tetracycline Hydrochloride
摘要： In this work, the highly ef?cient and low-cost Ag-AgBr/AlOOH plasmonic photocatalyst is successfully prepared via a simple and mild wet-chemical process and used for degrading high concentration methylene blue (MB) and tetracycline hydrochloride (TCH). The optimized 6-Ag-AgBr/AlOOH sample showed a 79% decomposition of TCH in 2 h, which is almost two times higher than that of bare AgBr (37%). For degrading MB, the photocatalytic activity of 6-Ag-AgBr/AlOOH (decomposing 84% in 2 h) showed a large enhancement as compared to bare AgBr (only 57%). The TEM, HRTEM, XRD, DRS, and XPS characterization results con?rm that Ag-AgBr is a composite catalyst formed by loading Ag nanoparticles onto AgBr surfaces and then loaded on to AlOOH. The possible mechanism proposed is that ?O?2 and ?OH radicals produced under sun light are the main active species for degrading MB and TCH. It is hoped that this work will open a new gateway to the synthesis of highly ef?cient and low-cost Ag-AgBr/AlOOH plasmonic photocatalysts for degrading organic pollutants.
关键词： tetracycline hydrochloride,degradation,Ag-AgBr/AlOOH,plasmonic photocatalyst,methylene blue
更新于2025-09-19 17:13:59