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AIP Conference Proceedings [Author(s) PROCEEDINGS OF THE 3RD INTERNATIONAL SYMPOSIUM ON CURRENT PROGRESS IN MATHEMATICS AND SCIENCES 2017 (ISCPMS2017) - Bali, Indonesia (26–27 July 2017)] - Preparation and characterization of TiO2/BiVO4 composite: Can this photocatalyst, under visible light, be able to eliminate rhodamine B from water and why?
摘要： Bismuth vanadate (BiVO4) can be composited with titanium dioxide (TiO2) to obtain a photocatalyst that can be activated by visible light. Such photocatalyst may be operated by solar light, principally, a free photon source. Many researchers have been working hard to find a stable, efficient, and low cost photocatalytic systems. In this presentation, we will report our effort to prepare and characterize TiO2/BiVO4 composite, which is responsive under visible light. The TiO2/BiVO4 composite was prepared by co-precipitation method, in which the self-prepared TiO2 nanotubes was immersed in solution containing bismuth (III) and vanadate ions under certain pH. The freshly obtained TiO2/BiVO4 was dried and subjected to a heat treatment, then was characterized by XRD, UV-visible diffuse reflectance spectrophotometer, SEM, and photo-electro-chemical working station. The results showed a crystal phase mixture of TiO2/BiVO4 composite system, which are anatase (2θ of 27.5°, 36.1°, 54.3°) and monoclinic scheelite, bismuth vanadate (2θ of 19°, 29°). The photocurrent evolution under visible light exposure was investigated carefully. The results showed that the composite system is active under visible light, due to visible light absorption by narrow bandgap semiconductor, namely BiVO4. While the heterojunction system in TiO2/BiVO4 composite enhanced the separation of electron and charge, eventually, the electron would flow from the conduction band of BiVO4 to conduction band of TiO2, so the photocurrent will be enhanced. When this composite was being applied to the photoelectrocatalytic reactor system, containing aqueous rhodamine B, the enhancement of photo-catalytic degradation of rhodamine B was also significantly observed. The influence of bias potential applied during photoelectrocatalytic degradation process will be further discussed.
关键词： degradation rhodamine B,TiO2/BiVO4 composite,photocatalyst
更新于2025-09-23 15:21:21
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Preparation of Highly Efficient CoFe2O4/Zn2SnO4 Composite Photocatalyst for the Degradation of Rhodamine B Dye from Aqueous Solution
摘要： CoFe2O4/Zn2SnO4 composite was synthesized using a simple two-step process and applied as a novel-efficient photocatalyst for the rhodamine B degradation from aqueous solution. Characterization techniques such as X-ray diffraction (XRD), N2 adsorption-desorption isotherms, scanning electron microscopy (SEM), EDS analysis, and diffuse reflectance spectroscopy were employed in order to investigate the physical and chemical properties of composite. Higher values of the specific surface area, pore volume and diameter, and a smaller band-gap energy promoted a greater catalytic activity of CoFe2O4/Zn2SnO4 composite when compared to Zn2SnO4. A rapid decolorization of dye solution was observed at 40 min of reaction using the CoFe2O4/Zn2SnO4 catalyst, being 2.5 times faster than the Zn2SnO4 alone. Therefore, the CoFe2O4/Zn2SnO4 composite shows extraordinarily high photocatalytic activity toward the degradation of rhodamine B dye from aqueous solution.
关键词： Coupled oxides,Photocatalysis,Rhodamine B,Synthesis,CoFe2O4/Zn2SnO4
更新于2025-09-23 15:21:21
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Defect engineered mesoporous 2D graphitic carbon nitride nanosheet photocatalyst for Rhodamine B degradation under LED light illumination
摘要： In this work, a nitrogen vacancy induced 2D mesoporous graphitic carbon nitrogen (g-C3N4) nanosheet photocatalyst was successfully synthesized through a simple two step thermal treatment method. The morphology of the nanosheet photocatalyst and the presence of nitrogen vacancy was explored through a wide range of characterization techniques. The as prepared photocatalyst possess an improved visible light absorption efficiency as confirmed from the UV-Visible diffuse reflectance spectroscopy (DRS). Moreover, the improved charge carrier separation efficiency of the nitrogen vacant material was demonstrated from the photoluminescence spectrum. Most importantly, the photocatalyst exhibited an excellent photodegradation efficiency towards rhodamine B (RhB) dye under the illumination of an 18 W LED light. The vacancy induced nanosheets demonstrated a degradation co-efficient of 0.074 min-1 in RhB degradation, which is 9.25 fold higher than that of the bulk g-C3N4. The nanosheets further exhibited an enhanced degradation efficiency toward tetracycline antibiotic. Furthermore, the photocatalyst displayed an outstanding stability even after 5 cycles. A plausible photocatalytic mechanism has also been explained based on the results obtained from the radical scavenging experiments. This study would provide insight into the defect induction mechanism into the 2D g-C3N4 nanosheet and expected to help in rationally designing vacancy induced materials with cost effective application in various environmental fields.
关键词： nitrogen vacancy,LED light irradiation,rhodamine B,mesoporous,2D g-C3N4 nanosheet
更新于2025-09-23 15:21:01
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CuAl Hydrotalcite Formed CuAl-Mixed Metal Oxides for Photocatalytic Removal of Rhodamine B and Cr(VI)
摘要： Mixed metal oxides (MMOs) are important semiconductor photocatalysts for water treatment, such as removal of organic dyes and metal ions. In this paper, CuAl hydrotalcite-like compounds (CuAl-HTLcs) were synthesized by the coprecipitation method using Al(NO3)3?9H2O and Cu(NO3)2?3H2O as raw materials. Cu2O/Cu2Al2O4 mixed metal oxides (MMO) were prepared by calcining CuAl-HTLcs at 900 °C. The obtained composites were characterized by various methods, including X-ray diffraction (XRD), Scanning electron microscopy (SEM), and UV-Vis diffuse reflectance spectroscopy (DRS), among others. Their photocatalytic activities towards removal of Rhodamine B (RhB) and Cr(VI) were evaluated by spectrophotometry. XRD revealed that CuAl-MMO composites were composed of high crystallinity Cu2O and Cu2Al2O4 grains. DRS showed the strong ultraviolet absorption ability of the composites. The electrochemical testing demonstrated CuAl-MMO composites with good photocatalytic activities towards the removal of Rhodamine B (RhB) and Cr(VI) under ultraviolet light, with reaction rate constants determined as 0.41 h?1 and 0.49 h?1, respectively. The relevant photocatalytic activities of CuAl-MMO composites were attributed to the synergy between the two components. Overall, these data look promising for future use of CuAl-MMO as an important photocatalyst for water remediation.
关键词： Photocatalysis,Rhodamine B,CuAl hydrotalcite,Cr(VI) solution,CuAl MMO
更新于2025-09-23 15:21:01
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{0 0 1}-Facet-Exposed Ag <sub/>4</sub> V <sub/>2</sub> O <sub/>7</sub> Nanoplates: Additive-Free Hydrothermal Synthesis and Enhanced Photocatalytic Activity
摘要： The synthesis of silver pyrovanadate, Ag4V2O7, nanoplates with exposed {0 0 1}-facets by a facile, additive-free hydrothermal method was described in this paper. The photocatalytic activity of rhodamine B over Ag4V2O7 samples under solar light irradiation was also evaluated. By using an equimolar mixture of NH4VO3 and AgNO3 with the presence of a suitable amount of ammonia, Ag4V2O7 nanoplates were obtained readily and purely at temperatures from 100 to 140°C for 4 h. The c-axis orientation growth of Ag4V2O7 nanoplates occurred and increased monotonously with temperatures in the range of over 100 up to 140°C. Further increase in hydrothermal temperature up to 220°C, the Ag4V2O7 phase no longer existed and the β-AgVO3 phase was formed instead. The photocatalytic activity of the optimized Ag4V2O7 sample comprising {0 0 1}-facet-exposed nanoplates with the highest degree of orientation was significantly higher than that of the random-oriented sample. The effects of using ammonia as a complexing agent on the structure, microstructure, texture, exposed facet, and photocatalytic activity of Ag4V2O7 samples were also investigated for the first time.
关键词： photocatalytic activity,hydrothermal synthesis,Ag4V2O7,rhodamine B,nanoplates,solar light irradiation
更新于2025-09-23 15:21:01
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Semiconductor Photocatalysis - Materials, Mechanisms and Applications || Alternative Approaches in Development of Heterogeneous Titania-Based Photocatalyst
摘要： Three alternative approaches for the development of heterogeneous photocatalysts are comparatively evaluated, namely (i) the use of molecular imprinting concept for the development of heterogeneous catalysts employing rhodamine B as template and sol–gel as synthesis route; (ii) the impregnation of TiCl4 on mixed nano- and micro-metric silicas, followed by calcination; (iii) the use of industrial and academic chemical residues as source of potential photocatalyst species impregnated on supports. All tests were carried on with rhodamine B as target molecule. For comparative reasons, photocatalytic tests were carried out with commercial titania (P25). The solids were characterized by nitrogen porosimetry, small-angle X-ray scattering (SAXS), zeta potential (ZP), diffuse reflectance spectroscopy in the ultraviolet region (DRS-UV), diffuse reflectance infrared Fourier transmission spectroscopy (DRIFTS), and Rutherford backscattering spectrometry (RBS). The supported catalysts resulting from silica nanoparticles and residue of the petrochemical industry achieved higher percentage of the dye degradation under ultraviolet (68.0 and 66.8%, respectively) radiation. The industrial waste reached the highest photocatalytic activity under visible (61%) radiation, while the commercial P25 achieved 82.0and 12.3% for ultraviolet and visible radiation, respectively. The textural and structural characteristics of the supported catalyst prepared with fumed silica and petrochemical waste (SiPe), namely the low-energy bandgap (1.8 eV), large surface area (280 m2 g?1), high pore volume (1.9 cm3 g?1), and high zeta potential value (?36.4 mV), may have been responsible for their high activity.
关键词： supported photocatalyst,molecular imprinting,Rhodamine B,titania,residue,silicas
更新于2025-09-23 15:21:01
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Rapid screening of rhodamine B in food by hydrogel solid-phase extraction coupled with direct fluorescence detection
摘要： Rhodamine B (RhB), which is vividly colored, although illegal and potentially carcinogenic, has been reported widely as present in various foods, including chili powder, preserved plums, sausage and sweets, presenting a significant health risk. In this work, solid-phase extraction (SPE), coupled with direct fluorescence detection on the same extraction medium, is proposed for rapid onsite screening for RhB in food without sample pretreatment. Parameters that affected extraction of RhB were explored. The lowest amount of RhB, detected on glass, was 2 ng and the lowest detectable concentration in food samples was 0.5 mg/kg, as verified by HPLC. The analysis time was less than 5 min, including sampling. In addition, the recovery rate of this method was found to be triple of that from the cotton gauze reported in literature. The proposed method has promise as a rapid, onsite screening protocol for food safety.
关键词： Solid-phase extraction,Fluorescence,Food safety screening,PVA hydrogel,Rhodamine B
更新于2025-09-23 15:19:57
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Characterization of tracers for two-color laser-induced fluorescence liquid-phase temperature imaging in sprays
摘要： The variation of the fluorescence spectral signature of tracer solutions with temperature enables temperature imaging measurements in liquids and sprays by simultaneously recording and rationing the fluorescence intensity detected in two separate wavelength channels. In this work, we recorded fluorescence spectra of ethanol-based solutions of nine laser dyes used as tracers (PTP, stilbene 1, coumarin 152, coumarin 153, rhodamine B, rhodamine 101, pyrromethene 597, DCM, and pyridine 1) after excitation at either 266, 355, or 532 nm (depending on the dye) for temperatures between 298 and 348 K (close to the boiling point of the solvent), and for concentrations (depending on dye) around 10 mg/l (i.e., ~ 10–5 mol/l). The influence of signal self-absorption was investigated for the tracers best suited for thermometry, rhodamine B and coumarin 152, where the latter is almost unaffected due to its large Stokes shift. In thin-film (100 μm) cells, possible concentration effects on the fluorescence spectrum were investigated in the absence of signal self-absorption in the 0.1–10 and 0.5–50 mg/l range for rhodamine B and coumarin 152, respectively. Sensitivities of the two-color intensity ratios were determined for two selected color detection channels for each tracer characterized by their center wavelength and spectral half width and conditioned on averaged intensities of larger than 10% of the spectral peak of their respective fluorescence spectrum. The use of coumarin 152 that showed the overall best spectroscopic properties was demonstrated for temperature imaging in a burning ethanol spray.
关键词： coumarin 152,rhodamine B,sprays,temperature imaging,two-color laser-induced fluorescence,tracers
更新于2025-09-23 15:19:57
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One-pot biosynthesis of SnO2 quantum dots mediated by Clitoria ternatea flower extract for photocatalytic degradation of rhodamine B
摘要： In this study, SnO2 quantum dots (QDs) have been successfully biosynthesized using Aparajitha (Clitoria ternatea) flower extract as the green reducing agent and then used as effective photocatalysts for the degradation of rhodamine B (RhB) under UV light irradiation. Clitoria ternatea flower extract contains flavanols and flavonoids, which can serve as reducing agents to convert Sn2+ precursors into Sn° NPs, which are then oxidized to 4–10 nm SnO2 QDs at 400 °C for 2 h. A blue shift in the adsorption wavelength of biosynthesized SnO2 QDs (3.66 eV) in comparison with bulk SnO2 (3.54 eV) is obtained, which can reduce the electron–hole recombination rate of SnO2. In addition, the specific surface area of SnO2 QDs is almost two times higher than that of bulk SnO2, resulting in the acceleration of photocatalytic degradation efficiency and rate of RhB under UVB light irradiation. The photodegradation performance of RhB over SnO2 QDs is highly dependent on several parameters, including H2O2 concentration, catalyst dosage, and pH. The liquid chromatography-mass spectrometric spectra and radical scavenger experiments indicate that the hydroxyl radicals play a crucial role in photodegradation, which can undergo N-deethylation and ring cleavage reactions to produce intermediates of N, N-diethyl-N’-ethylrhodamines, dihydroxybenzoic acid, and maleic acid. Moreover, a possible reaction mechanism for RhB photodegradation over SnO2 QDs is proposed. Results obtained in this study clearly indicate that the extract is an effective bioreagent to develop the green chemistry for the one-pot synthesis of SnO2 QDs photocatalysts for the degradation of pollutants in aqueous solutions.
关键词： Rhodamine B (RhB),Clitoria ternatea flower extract,SnO2 quantum dots,Photocatalytic activity
更新于2025-09-23 15:19:57
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Green and Orange Emissive Carbon Dots with High Quantum Yields Dispersed in Matrices for Phosphor-Based White LEDs
摘要： Carbon dots (CDs) have aroused more interest in the LED phosphor. High quantum yields and suppressing solid-state luminescence quenching are the key factors for CDs to prepare high-quality phosphors. In this work, orange and green emissive CDs (O-CDs and G-CDs) with very high absolute quantum yields (abs. QYs: 85.19% at natural pH and 96.12% at pH 9.0 for G-CDs; 34.89% in aqueous solution and 77.54% in ethanol for O-CDs) were achieved. Then, sodium silicate and PVA were selected as matrices to suppress their aggregation-induced quenching effect. Phosphor powder was prepared by microwave-assisted pyrolysis of sodium silicate and films by self-assembling of PVA in the presence of the CDs. The phosphor powder simultaneously containing G-CDs and O-CDs (G-O-CDs-phosphor) presents bright yellow fluorescence but owns a relatively low abs. QY. However, O-CDs/PVA and G-CDs/PVA phosphor films possess very high abs. QYs of 51.51% and 72.81%, respectively. LEDs constructed by coating G-O-CDs-phosphor on a blue chip exhibited a cool white color and a color rendering index (CRI) of 78. Interestingly, high-quality warm white LEDs owning a superior CRI of 93 were achieved by the O-CDs/PVA and G-CDs/PVA films. By comparison, PVA is more suitable to maintain the high performance of G-CDs and O-CDs for high-quality phosphors.
关键词： White LEDs,Phosphor,Carbon dots,High quantum yield,Rhodamine B
更新于2025-09-23 15:19:57