Photocatalytic Degradation Of Rhodamine Research Articles

Preparation of ZnFe2O4@TiO2 Novel Core-Shell Photocatalyst by Ultrasonic Method and Its Photocatalytic Degradation Activity

ZnFe2O4 microspheres were prepared by solvothermal method, and a novel ZnFe2O4@TiO2 core-shell composite photocatalyst was prepared by ultrasonic (denoted as ZT-x) and mechanical stirring (denoted as ZTM-1.2). The morphology, structure, magnetic, and optoelectronic properties of the catalyst were investigated comprehensively, and the degradation performance of the catalyst was explored through the photocatalytic degradation of Rhodamine B (RhB) under UV light. The concentration of RhB was 10 mg/L, and the catalyst concentration was 0.3 g/L. ZT-1.2 showed the best photocatalytic degradation activity, and the degradation rate of RhB reached 97.3% within 60 min. The degradation ability of the catalyst was further evaluated by Methylene blue (MB), Methyl orange (MO), Phenol, and Ofloxacin (OFX). ZT-1.2 also exhibited excellent stability. The improved catalyst degradation performance was attributed to constructing a Z-type heterojunction. Moreover, the low-efficiency degradation of ZTM-1.2 was caused by catalyst agglomeration and low TiO2 loading, confirming the superiority of the ultrasonic method and providing a new method for the preparation of magnetically recoverable TiO2-based core-shell photocatalyst.

Deep-Eutectic-Solvent-Assisted Synthesis of a Z-Scheme BiVO4/BiOCl/S,N-GQDS Heterojunction with Enhanced Photocatalytic Degradation Activity under Visible-Light Irradiation.

Z-scheme heterojunction photocatalytic nanomaterial designs have attracted attention due to their high catalytic performance. Deep eutectic solvents (DESs) have been used as green, sustainable media, acting as solvents and structure inducers in the synthesis of nanomaterials. In this work, a novel visible-light-absorption-enhanced bismuth vanadate/bismuth oxychloride/sulfur, nitrogen co-doped graphene quantum dot (BiVO4/BiOCl/S,N-GQDS) heterojunction photocatalyst was prepared in a deep eutectic solvent. The photosynthetic activity of the BiVO4/BiOCl/S,N-GQDS composite was determined by the photocatalytic degradation of rhodamine B (RhB) under visible-light irradiation. The results showed that the highest photocatalytic activity of BiVO4/BiOCl/S,N-GQDS was achieved when the doping amount of S,N-GQDS was 3%, and the degradation rate of RhB reached 70% within 5 h. The kinetic and photocatalytic cycles showed that the degradation of Rhb was in accordance with the quasi-primary degradation kinetic model, and the photocatalytic performance remained stable after four photocatalytic cycles. Ultraviolet–visible diffuse reflectance (UV-DRS) and photoluminescence (PL) experiments confirmed that BiVO4/BiOCl/S,N-GQDS ternary heterojunctions have a narrow band gap energy (2.35 eV), which can effectively improve the separation efficiency of the photogenerated electron–hole pairs and suppress their complexation. This is due to the construction of a Z-scheme charge process between the BiVO4/BiOCl binary heterojunction and S,N-GQDS, which achieves effective carrier separation and thus a strong photocatalytic capability. This work not only provides new insights into the design of catalysts using a green solvent approach but also provides a reference for the study of heterojunction photocatalytic materials based on bismuth vanadate, as well as new ideas for other photocatalytic materials.

Synthesis of Z-scheme (001)-TiO2/Bi5O7I heterojunctions with enhanced interfacial charge separation and photocatalytic degradation of Rhodamine B

Synthesis of Z-scheme (001)-TiO2/Bi5O7I heterojunctions with enhanced interfacial charge separation and photocatalytic degradation of Rhodamine B

A microwave-assisted solvothermal method to synthesize BiOCl microflowers with oxygen vacancies and their enhanced photocatalytic performance

The photocatalytic performance of the catalysts are highly dependent on their morphology and the separation efficiency of photo-generated carriers. In this work, the self-assembled BiOCl microflowers with oxygen vacancies (OVs) were synthesized by facile microwave-assisted solvothermal method. The ethylene glycol was applied as solvent, reductant and soft templates of microflowers. As the preparation temperature increased from 100 ℃ to 160 ℃, the morphology of BiOCl was transformed from microflowers to nanosheets, and the concentration of OVs increased gradually. The photocatalytic performance of BiOCl was evaluated by photocatalytic degradation of Rhodamine B (RhB), Methylene blue (MB) and Ciprofloxacin (CIP) under visible light irradiation. It is indicated that the excessive OVs would inhibit the separation and migration of photo-generated carriers. Benefiting from the optimum OVs concentration and enhanced specific surface area, the BiOCl-100 microflowers exhibited a superior photocatalytic performance. The degradation constants for RhB, MB and CIP by BiOCl-100 were estimated to be 0.512, 0.022 and 0.022 min−1, which were 4.3, 1.7 and 5.5 folds higher than BiOCl-100-w nanosheets (with no OVs), respectively. This work demonstrated the superior photocatalytic performance of BiOCl microflowers with optimum OVs, which could be also applied to design of other highly efficient photocatalysts.

Facile synthesis, optical properties regulation and boosted photocatalytic degradation performance for organic pollutants of Mn:CuInS2/CdS nanocrystals

In this work, 3-mercaptopropionic acid (MPA) coated transition metal ions doped CuInS2/CdS nanocrystals were synthesized by using a facile, green and safe chemical solution method combined with epitaxy growth technology. By changing the concentration of Mn2+ and adjusting the microstructure and properties of CuInS2/CdS based nanocrystals, nanocrystals with specific phase structure, composition, scale and optical properties were obtained. The largest PL quenching was observed in Mn:CuInS2/CdS, which may be due to the significantly improved photogenerated charge transfer between Mn and CuInS2/CdS. The results show that doping of Mn into the lattice of CuInS2/CdS obviously decreases the crystal size, changes band gap and improves visible light absorption capability. The photocatalytic degradation of rhodamine B (RhB) solution by nanocrystals was tested under visible light. The results show that the highest degradation efficiency was achieved when the doping concentration was x = 0.05. We believe that heterojunction is beneficial to improve the separation efficiency of photogenerated carriers and the application of nanocrystals in the visible light region. In addition, the introduction of doped ions in nanocrystals can not only promote the formation of defects or the change of energy bands, but also improve the separation efficiency of photogenerated carriers. From the free radical trapping experiments, we find that h+ is the main active species in the photocatalytic degradation of RhB by CuInS2/CdS nanocrystals. This study will provide an important scientific reference for the development and utilization of new water antifouling materials.

Enhanced visible light photocatalytic performance of a novel FeIn2S4 microsphere/BiOBr nanoplate heterojunction with a Z-scheme configuration.

The rational design of heterojunction photocatalysts is an effective way to improve semiconductor photocatalytic activity. The simple solvothermal method was used to successfully prepare visible light-driven FeIn2S4 microsphere/BiOBr nanoplate binary heterojunction photocatalysts with varying FeIn2S4 contents. The crystal structure, morphology, surface composition, specific surface area, charge separation, and optical properties of the as-prepared photocatalysts were investigated using a variety of analytical methods. In the photocatalytic degradation of rhodamine B, the FeIn2S4/BiOBr photocatalysts obtained a degradation efficiency of 96% within 60min, which was approximately 5.33 and 2.59 times higher than pure FeIn2S4 and BiOBr, respectively. Radical trapping experiments and ESR measurements revealed the main active species (·OH, ·O2-, and h+) produced during photocatalytic degradation. The increased photocatalytic activity was due to the formation of Z-scheme heterojunctions between FeIn2S4 and BiOBr, which contributed to the improved effective charge separation of photogenerated charge carriers, augmented specific surface area, and enhanced redox capacity. It is expected that our current study will provide a hopeful way for future environmental remediation research.

Understanding the effect of polymer concentrations on the phase formation and activity of electrospun nanofibrous photocatalyst

One-dimensional titanium dioxide electrospun nanofiber have been extensively studied, it provides channels for quick charge transfer due to their long axial ratio, but as per the experiment reports the phase formation is not conclusive about the origin of the crystallinity of titanium oxide, nor about role of polymer amount. In this study, the effect of sacrificial polymer in the electrospun solution on Ti-O bonds breaking and on the arrangement of TiO6 octahedra was obtained for different titanium oxide phase formations. In particular, polymer-metal precursor plays the role of Magnéli phase formation at low temperature. The nanofibers were prepared at different titanium butoxide and polymer concentrations with the optimization of electrospinning parameters such as electric field strength, the flow rate of the electrospinning solution, the distance between the nozzle and the receiving drum collector, and the speed of the rotating collector. The effect of polymer concentration on the crystallinity and phase compositions was examined in detail. Surprisingly, the percentage of anatase phase was found to decrease with increasing the polymer amount with a fixed annealing temperature. The experimental results show that carrier polymer polyvinylpyrrolidone is not only involved in the fiber formation through chain entanglements but plays a significant role to control TiO6 octahedral configurations and connectivity. More polymers promote edge-sharing between TiO6 rather than corner-sharing. We demonstrate the efficient photocatalytic activity of the mixed phase TiO2 nanofiber in the photocatalytic degradation of Rhodamine B dye. A significant increase in the reaction rate was observed with the increase of the Titanium butoxide:polyvinylpyrrolidone ratio. It was found that 70% anatase and 30% rutile mixed phase TiO2 nanofiber catalysts exhibit optimum photocatalytic activity with rate constant values of 0.345 min−1. The mechanism relates to the interfacial charge carrier at the junction of anatase and rutile band alignment.

ZnO Nanorods Grown on Rhombic ZnO Microrods for Enhanced Photocatalytic Activity.

In this paper, the formation of rhombic ZnO microrods surrounded by ZnO nanorods was realized on the surfaces of zinc foils using a hydrothermal method. The photocatalytic degradation of Rhodamine B solution was used to test the photocatalytic performance of the prepared samples. Compared with the rhombic Zn(OH)F and ZnO microrods grown on zinc foils, the hierarchical micro/nanostructures formed by ZnO nanorods surrounding the surfaces of rhombic ZnO microrods have better photocatalytic performance. The experimental results are mainly due to the fact that the hierarchical ZnO micro/nanostructures formed by ZnO nanorods surrounding the surface of the rhombic ZnO microrods have a larger surface area compared with the rhombic Zn(OH)F and ZnO microrods. More importantly, the photocatalytic circulation experiments indicate that ZnO nanorods grown on rhombic ZnO microrods can be recycled and have a relatively stable photocatalytic performance.

Photocatalytic degradation of rhodamine B by Bi2O3/Cs3PW12O40 composite under visible-light irradiation and its enhanced photocatalytic activity

Photocatalytic degradation of rhodamine B by Bi2O3/Cs3PW12O40 composite under visible-light irradiation and its enhanced photocatalytic activity

Metal doped graphitic carbon nitride prepared by a bubbling template method for photo-degradation of organic pollutants

A bubbling template method was used to prepare metal-doped graphitic carbon nitride (g-CN), with ammonium salts as the bubbling templates. Effects of metal types, metal loading, as well as the species and dosage of ammonium salts, on the structure, physicochemical properties and catalytic performances of g-CN were systematically investigated. Photocatalytic degradation of rhodamine B (RhB) was used as a model reaction to evaluate the catalytic performances of the materials. The results indicated that K0.02-CN(CA-3), which was prepared with K doping and with ammonium carbonate as the bubbling template, exhibited the best activity, with 99.7% RhB conversion obtained at 17.5 min, which is 3.2 times higher than that of g-CN. This can be attributed to the improved surface area, widened light absorption range and enhanced electron–hole separation efficiency of K0.02-CN(CA-3), as compared to these of g-CN. This material was also active for photo-degradation of other pollutants and has good reusability. A sketchy mechanism indicating the reactive intermediates of reaction was proposed.

Morphology Control of TiO2 Nanorods Using KBr Salt for Enhancing the Photocatalytic Activity of TiO2 and MoS2/TiO2 Heterostructures.

In this study, the effect of KBr salt on the growth of TiO2 nanorods (NRs) was systematically studied. The addition of KBr with different concentrations provides a controllable growth of TiO2 NRs using hydrothermal method. The results revealed that the presence of KBr molecules affects the growth rate by suppressing the growth in the lateral direction and allowing for axial growth. This results in affecting the morphology by decreasing the diameter of the nanorods, and increasing the free space between them. Enhancing the free spaces between the adjacent nanorods gives rise to remarkable increase in the internal surface area, with more exposure side surface. To obtain benefit from the enlargement in the inner surface area, TiO2 NRs were used for the preparation of MoS2/TiO2 heterostructures. To study the influence of the morphology on their activity, TiO2 NRs samples with different KBr concentrations as well as the MoS2/TiO2 heterostructures were evaluated towards the photocatalytic degradation of Rhodamine B dyes.

Highly efficient and stable Fe2O3/g-C3N4/GO nanocomposite with Z-scheme electron transfer pathway: Role of photocatalytic activity and adsorption isotherm of organic pollutants in wastewater

In this work, we have used a hematite ferric oxide (Fe2O3), graphitic carbon nitride (g-C3N4), and graphene oxide (GO) to design highly efficient visible light active ternary nanocomposite for the exclusion of organic contaminants in an aqueous system. The reusability test and powder X-ray diffraction (XRD) analysis of 10 wt% Fe2O3/g-C3N4/GO (10FGG) nanocomposite before and after four consecutive cycles run demonstrated that the synthesized photocatalyst has impressive stability. The X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) analyses indicate the presence of all the elements in the composite material without any impurities. Among the synthesized materials, the photocatalytic degradation of rhodamine B (RhB), methylene blue (MB) and 3-methyl-4-nitrophenol were best achieved by 10FGG nanocomposite. High-performance liquid chromatography (HPLC) analysis showed the transformation of 3-methyl-4-nitrophenol into 3-methyl-4-aminophenol as one of the intermediate products followed by complete degradation under visible light irradiation. The terephthalic acidphotoluminescence (TA-PL) experiment in NaOH and nitroblue tetrazolium (NBT) in water reveal the continuous generation of hydroxyl and superoxide radicals, respectively. The low PL signal for 10FGG revealed that Fe2O3, g-C3N4, and GO could collectively minimize the recombination rate of electron-hole pairs and hence raise the sum of carrier charges (h+ and e−) accessible for photoreactions, confirming the improved photocatalytic activity of nanocomposite. Based on the data obtained, a plausible Z-scheme photodegradation mechanism of the pollutants with 10FGG nanocomposite has been sketched out.

Excellent photocatalytic activity of MoO3-adorned g-C3N4 systems: Construction of S-scheme heterojunction

To alleviate harmful pollutants in water, photocatalytic technology, which offers green degradation of pollutants, is being used. The g-C3N4 is a metal-free organic polymer semiconductor photocatalyst widely used in photocatalysis. However, some drawbacks have limited its practical application. Thus, constructing of semiconductor heterojunction with appropriate band structure to improve photocatalysis activity for g-C3N4is an effective and common means to overcome the drawbacks. Therefore, in this study, MoO3/g-C3N4 (MoCN) was prepared via the one-step calcination method. The photocatalytic performance of the composite was evaluated via photocatalytic degradation of rhodamine B (RhB) and the data revealed that the 3MoCN composite semiconductor greatly enhanced the activity (about 6.3 times) of pure g-C3N4 toward the degradation of RhB. Meanwhile, the free radical masking experiments suggested O2− as the major oxidizing species in the MoCN system. The specific area of the composite system of MoCN was 3.7-fold higher than that of pure g-C3N4. Furthermore, the photoelectric properties tests and DFT demonstrated improved photoactivity of MoO3/g-C3N4 due to the movement of Fermi levels and built-in electric field close to the S-scheme heterojunction interface. Our work demonstrated a simple strategy to prepare efficient photocatalysts for environmental remediation.

Preparation and characterization of ZnO/graphene/graphene oxide/multi-walled carbon nanotube composite aerogels.

ZnO/Graphene (G)/Graphene Oxide (GO)/Multi-walled Carbon Nanotube (MCNT) composite aerogels with a three-dimensional porous structure were prepared by the sol-gel method under average temperature and alkaline conditions, combined with freeze-drying process and heat treatment process. The photocatalytic degradation of Rhodamine B (RhB) was mainly studied. The scanning electron microscope (SEM) test results showed that the morphology uniformity of the ZnO/G/GO/MCNT composite aerogel was significantly enhanced, which effectively solving the agglomeration problem of MCNT and ZnO. The photocatalytic degradation test results of RhB show that due to the synergistic effect of physical adsorption and photocatalytic degradation, the total degradation efficiency of RhB by ZnO/G/GO/MCNT could reach 86.8%, which is 3.3 times higher than that of ZnO. In addition, the synergistic effect of ZnO and G effectively hinders the recombination of photo-generated electron-hole pairs and enhances photocatalytic activity. The ZnO/G/GO/MCNT composite aerogel can be applied in the visible light catalytic degradation of water pollution.

Environmental friendly nano-star CdS coupled ZnS on bi-polymer matrix: Unravelling defects-rich nanoplatform for ultrahigh white light active direct S-scheme photodegradation of organic pollutants

Photocatalysis is a reliable technology to treat polluted wastewater. Herein, we report S-scheme photocatalyst namely ZnS/CdS nanocomposites (NCs) with S-vacancies and interstitial defect states, immobilised on the polymer matrix of cellulose and chitosan. It showed significant performance in photocatalytic degradation of Rhodamine B (RhB) dye. Defect sites present in ZnS facilitates charge separation and two-photon excitation concomitantly with a bandgap shift in ZnS/CdS NCs to 2.65 eV and promotes visible light harvesting. XRD analysis demonstrated the highly crystalline nature of the NCs. TEM and SEM were used to observe the crystal phases, particle morphology and defect sites. XPS and EDAX ensured the composition and purity of the synthesized NCs. FTIR displayed the peaks representing the bonds present in metal sulphides and chitosan/cellulose matrix. The photodegradation of RhB by ZnS/CdS NCs reached a maximum of 99.18% in 120 min which displayed 6.8 and 10.25 times higher rate than pure ZnS and CdS respectively. Further, ZnS/CdS NCs was able to achieve the TOC reduction of 86% after the photodegradation of RhB. Defect engineering played a vital role in enhancing the photocatalytic activity of NCs. PL spectra revealed the prolonged life time of photogenerated charge carriers and EIS analysis was used to investigate the charge mobility of the fabricated materials. Superoxide radical was found to be the major radical involved in photodegradation of RhB by NCs. The degradation pathway of RhB was elucidated based on GC-MS/MS analysis. The recyclability of NCs was tested for six consecutive cycles and remarkable stability was observed. The results of in vitro cytotoxicity assay, and cellular reactive oxygen species generation suggest that ZnS/CdS NCs are safety photocatalysts to environment and human being.

Photocatalytic Degradation of Rhodamine B Dye by Nanocomposites: A Review

Pollution by textile dyes on waterbodies is an issue for both human health and the environment. To remove/degrade dyes, many approaches (coagulation, membrane separation, and adsorption) have been investigated. However, the use of semiconductor-assisted materials in conjunction with sustainable solar energy has emerged as a possible solution to the problem. Although single component photocatalysts have been tested, composites of semiconductor materials are being employed owing to their low efficiency and stability due to the high recombination rate electron-hole pair and inefficient visible light absorption. By combining two or more semiconductor components, semiconductor heterojunction systems are created. Overall stability is increased by the synergistic impact of their features, such as adsorption and better charge carrier movement. This paper discusses current advances in advanced nanocomposite materials utilized as photocatalysts, as well as the utilization of heterojunctions, crystallinity, and doping to improve photocatalytic characteristics. The conclusion includes a summary, research gaps, and a forecast for the future. This study will aid in the development of efficient heterostructure photodegradation systems by providing a comprehensive appraisal of recent advances in demonstrating effective nanocomposites for photodegradation of Rhodamine B dye under ideal circumstances.

Effect of metal–ligand ratio on the rhodamine B photodegradation activity of metal-organic framework materials based on bismuth and trimesic acid

In this study, the photocatalytic degradation of rhodamine b (RhB) is investigated over metal-organic framework materials based on bismuth and trimesic acid (Bi-BTC) with different metal-to-ligand molar ratios. All obtained products are characterized by using powder X-ray diffraction, scanning electron microscopy, and UV–vis diffuse reflectance spectroscopy. It is found that decreasing the metal-to-ligand ratio below 1:1 produces high crystallinity and long rod-like crystals of Bi-BTC. For the metal-to-ligand molar ratios 5:1 and 1:1, we obtain low crystallinity of Bi-BTC. Additionally, a lower metal-to-ligand ratio in the Bi-BTC photocatalyst leads to the higher efficiency compared to other Bi-BTC photocatalysts. The metal-to-ligand ratio of 1:20 (Bi-BTC-0.05) favors the highest efficiency, in which 97.81% rhodamine B (RhB) is removed after 150 min of irradiation. The results should open a new approach to optimize the desired Bi-BTC structure for a target application.

A detailed structural analysis, morphological and optical study of Mg-Zn nano ferrite

Mg-Zn nanoferrite with the composition of Mg0.4Zn0.6Fe2O4 was prepared using the citrate precursor process. Detailed structural analysis was performed on Mg-Zn nanoferrite to calculate crystallite size, lattice constant, X-ray density, bulk density, and porosity using XRD data. Also, the strain on the sample was calculated by plotting Williamson – Hall (W-H) plot. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were performed to study morphological and optical properties. The spinel structure was confirmed by XRD with a crystallite size of 38 nm. SEM micrograph of the sample showed almost spherical-shaped nanoparticles. FTIR spectra disclosed two characteristic bands showing tetrahedral (A) and octahedral (B) site occupancies. Under UV–visible light irradiation, photocatalytic degradation of rhodamine B dye and the degradation efficiency is obtained to be 70 % in 60 min. Therefore, it is concluded that Mg0.4Zn0.6Fe2O4 is a promising material for water purification.

Polyaniline-assisted hydrothermal synthesis of TiO2 with tunable OVs and enhanced photocatalytic performance for destruction of rhodamine B and ciprofloxacin

For purpose of ameliorating the photocatalytic capability of TiO2, TiO2 photocatalysts were facilely fabricated by a hydrothermal strategy through the assistance of polyaniline (PANI). TiO2 samples prepared (PANI-TiO2) were characterized in detail by miscellaneous characterization approaches. The consequences affirm that PANI-assisted preparation can construct tunable oxygen vacancy (OVs), notably heightening the photocatalytic capability of TiO2. Photocatalytic degradation of rhodamine B (RhB) and ciprofloxacin (CIP) were carried out under Xenon lamp irradiation. Compared with the blank TiO2, PANI-TiO2 photocatalysts show superior photocatalytic capability to the blank TiO2. When the weight proportion of PANI/TiO2 is 4%, the degradation efficiency of RhB and CIP reaches 92.6% and 89.9% respectively, and the first-order kinetic constant of RhB and CIP over the sample is 3.7 and 1.7 times of that on the reference TiO2. This demonstration offers a potent reference for fabrication of effective photocatalysts for destruction of organic contaminants.

Degradation of environmentally harmful textile dye rhodamine B using silicate ceramic photocatalysts

The current study focuses on the photocatalytic degradation of Rhodamine B (RhB) dye using Larnite, Forsterite, and Strontium orthosilicate ceramics under UV light irradiation. Using glycine as a fuel, an energy-efficient solution combustion method was used to obtain the respective silicate materials. Powder XRD, FT-IR, SEM, TEM, and BET were employed to investigate the obtained materials' phase identification, surface morphology, and surface area. The bandgap measurements of the silicate ceramics were analyzed using a DRS spectrometer, and the results are in the range of 2.7–2.8 eV. The DRS spectra results revealed that silicate ceramics can decompose the Rhodamine B dye when exposed to UV light. The photocatalytic degradation tests show that larnite is a more efficient photocatalyst for the degradation of rhodamine B than the other tested silicate ceramics, with degradation efficiencies of approximately 87% (larnite), 82% (strontium orthosilicate), and 79% (strontium orthosilicate) (forsterite). As a result, silicate ceramics can be thought of as a potential material for enhanced environmentally harmful textile dye degradation applications.