Photodegradation Of Organic Dyes Research Articles

Sol–gel synthesized lithium–cobalt co-doped titanium (IV) oxide nanocomposite as an efficient photocatalyst for environmental remediation

Abstract In this study, lithium cobalt co-doped titanium oxide (Li:Co-TiO2) was reported via the sol–gel method in a one-pot synthesis approach and their potential applications were evaluated for the photodegradation of organic dye as photocatalysts. The structural and optical properties of the photocatalysts were respectively elucidated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and diffuse reflectance spectroscopy (DRS). The morphological and elemental composition of the Li:Co-TiO2 was established by high-resolution field-emission scanning electron microscopy (FESEM) coupled with EDX, which confirmed a successful preparation of the photocatalysts. The modification of TiO2 with Li:Co changes the optical properties of the pristine TiO2 with a reduction in the bandgap (3.26–2.8 eV) of the resultant photocatalysts. The photocatalytic activity of Li:Co-TiO2 composites was examined for their efficacy through the degradation of Methylene Blue (MB) dye. The photodegradation revealed an improved performance of Li:Co-TiO2 in the degradation of MB compared to pristine TiO2. The total amount of the degraded MB dye within the total time interval of the irradiation was recorded to be 72 % and 87 % for TiO2 and Li:Co co-doped TiO2 respectively. The enhanced results obtained from the photocatalytic activity of Li:Co-TiO2 to degrade MB, suggest that the composite is a potential candidate for environmental remediation and photocatalysis applications.

Fe-Doped g-C3N4/Bi2MoO6 Heterostructured Composition with Improved Visible Photocatalytic Activity for Rhodamine B Degradation.

The binary heterostructured semiconducting visible light photocatalyst of the iron-doped graphitic carbon nitride/bismuth molybdate (Fe-g-C3N4/Bi2MoO6) composite was prepared by coupling with Fe-doped g-C3N4 and Bi2MoO6 particles. In the present study, a comparison of structural characteristics, optical properties, and photocatalytic degradation efficiency and activity between Fe-doped g-C3N4 particles, Bi2MoO6 particles, and Fe-g-C3N4/Bi2MoO6 composite was investigated. The results of X-ray diffraction (XRD) examination indicate that the hydrothermal Bi2MoO6 particles have a single orthorhombic phase and Fourier transform infrared (FTIR) spectroscopy analysis confirms the formation of Fe-doped g-C3N4. The optical bandgaps of the Fe-doped g-C3N4 and Bi2MoO6 particles are 2.74 and 2.73 eV, respectively, as estimated from the Taut plots obtained from UV-Vis diffuse reflectance spectroscopy (DRS) spectra. This characteristic indicates that the two semiconductor materials are suitable for absorbing visible light. The transmission electron microscopy (TEM) micrograph reveals the formation of the heterojunction Fe-g-C3N4/Bi2MoO6 composite. The results of photocatalytic degradation revealed that the developed Fe-g-C3N4/Bi2MoO6 composite photocatalyst exhibited significantly better photodegradation performance than the other two single semiconductor photocatalysts. This property can be attributed to the heterostructured nanostructure, which could effectively prevent the recombination of photogenerated carriers (electron-hole pairs) and enhance photocatalytic activity. Furthermore, cycling test showed that the Fe-g-C3N4/Bi2MoO6 heterostructured photocatalyst exhibited good reproducibility and stability for organic dye photodegradation.

Fabrication and characterization of C–doped TiO2 nanoparticles for the photodegradation of organic dyes

A low-cost sol-gel method is used to synthesize C-doped TiO2 (C–TiO2) nanoparticles. Nanoparticles of undoped TiO2 and varying C weight percentages (4%, 6%, and 8%) of C–TiO2 are generated. XRD, FTIR, FESEM-EDS, UV–Vis DRS, PL, BET, and XPS are used to analyze the characteristics of all the nanoparticles. The EDS data indicate that the TiO2 lattice has been successfully doped with carbon. The band-gap energy of 6% C–TiO2 is shifted to 2.94 eV, as confirmed by UV–Vis DRS, resulting in improved visible-light absorption and, hence, increased photocatalytic activity by lowering the electron-hole recombination rate. Under natural sunlight irradiation, 6% C–TiO2 achieves a 91% removal efficiency of Rhodamine B (RhB) dye in 90 min and 84% removal efficiency of Congo Red (CR) dye in 30 min. A probable photodegradation pathway was estimated using the scavenger test, and the •O2 − and •OH radicals are recognized as potentially active species for RhB degradation.

Enhancement photocatalytic activity of CeO2 infused CA@Gelatin nanocomposites for the degradation of organic dyes under UV-light irradiation

In the present study, facile 100 % recoverable handpicked CeO2/CA@GEL (CA; Cellulose acetate, GEL; Gelatine) nanocomposite thin film photocatalyst were successfully synthesized by simple solution cast method. The efficacy of the CeO2/CA@GEL was tested against the photodegradation of organic dyes viz Crystal violet (CV) and Rhodamine-B (RhB) under visible light irradiation. The CeO2/CA@GEL exhibited excellent photocatalytic activity, durability and utmost 80.52 % (CV) and 82.65 % (RhB) degradation of the dye solution was achieved within 60 min. The CeO2/CA@GEL showed the excellent degradation efficiency compared to pure CeO2 Nanoparticles. The reactive oxidative species involved in the photocatalytic reaction is superoxide radical anion (O2 radical) and OH radical under visible light irradiation by trapping experiments. The 100 % recovery of the photocatalyst was achieved by simple handpicking process and stable unto its 3rd usage.

MXene/Ag3PO4 modified PVDF composite membranes for efficient interfacial evaporation and photodegradation

Solar-powered interface evaporation is considered a promising technology to obtain freshwater from non-potable water by using sustainable solar energy. However, research on combining the photocatalytic effect with solar interfacial evaporation technology to go for photothermal conversion materials with full solar spectrum utilization for photothermal and photodegradation capabilities is still scarce. Due to the unique optical properties of MXene, a novel MXene/Ag3PO4-based membrane with synergistic photothermal and photocatalytic effects was developed from the perspective of practical applications such as water purification, photodegradation of organic dyes and antibacterial properties. In this paper, polyvinylidene fluoride (PVDF) and carbon black (CB) were used as the substrate, calcium carbonate (CaCO3) and hydrochloric acid (HCl) were selected as the pore-forming agent for hydrophilic modification, and MXene/Ag3PO4 serves as the photocatalyst. The prepared composite polyvinylidene fluoride membrane (PCC-MXene/Ag3PO4) with Schottky junction, possesses a rich pore structure, abundant water molecule transport channels, high light absorption ability, and low thermal conductivity, which lead to a good performance in solar interface evaporation, photodegradation and antibacterial. The superhydrophobicity and floatability of the nanosponges in water enable them to continuously pump water, which greatly promotes the dissolution of salt accumulation. With the help of porous nanosponges, PCC-MXene/Ag3PO4 exhibits excellent evaporation stability and salt resistance under 1 kW m−2 solar irradiation, as well as photodegradation of organic dyes. In addition, the PCC-MXene/Ag3PO4 membrane has the properties of self-buoyancy, electrical conductivity, and superior flexibility. Therefore, considering the simple preparation method and fine performances, the PCC-MXene/Ag3PO4 mixed membrane has great application potential in the study of interface evaporation, photodegradation of organic dyes, and antibacterial properties.

Visible Light-Induced Photocatalytic Degradation of Methylene Blue Using Copper-Doped Carbon Dots One-Step Derived from CCA-Wood

Developing novel eco-friendly broad-spectrum visible light photocatalysts for dye removal is one of the urgent problems for water treatment. Here, copper-doped carbon dots (CDs) were reported to be directly fabricated from chromated copper arsenate (CCA) wood waste for the photocatalytic degradation of the methylene blue dye. The properties of the resulting CDs were thoroughly characterized and analyzed, preceding an investigation into the adsorption kinetics of dye degradation. The kinetic study showed that reactant concentration was the rate-limiting factor. The obtained CDs showed a 151 mg/g photocatalytic degradation capacity. Comparing pure CDs to CDs/TiO2 composites, the former demonstrated higher photodegradation efficiency. This superiority can be attributed to the synergistic action of adsorption and photocatalytic degradation working in tandem. This study prepared Cu doped CDs and elucidated the photocatalysis mechanism of methylene blue degradation by CDs. The photodegradation of organic dyes through CDs derived from waste CCA wood emerges as an eco-friendly, facile, and highly efficient method.

Synthesis of Novel Nanocomposite CaO/AC/ZnO from Biogenic Wastes of Date Palm Seeds from The Najran Region (Saudi Arabia) and Eggshells for Degradation of Methylene Blue

Metal nanoparticles and activated carbon-based nanocomposite materials are gaining popularity due to their numerous potential applications in a wide range of materials science areas. The current study aims to create novel photocatalyst frameworks for nanocomposites that were synthesized from biogenic waste and used to photodegrade methylene blue (MB) in wastewater under visible light. The activated carbon from date seeds was calcinated at a temperature of 700°C for two hours, and its surface was improved using zinc oxide nanoparticles and calcium oxide nanoparticles manufactured from eggshells at 900oC. XRD, FT-IR, SEM, BET, and TEM analyses were used to characterize the produced nanocomposites. The synthesized nanocomposite photocatalytic activity was evaluated by degrading MB dyes, its model of water pollution. The results showed that the nanocomposite CaO/AC/ZnO has a mesoporous structure with great sorption capability. Also, the photodegradation efficiency of MB using AC, CaO, AC/ZnO, and CaO/AC/ZnO nanocomposite was 33.23, 37.58, 54.61, and 88.92%, respectively, after100 min of sunlight irradiation indicating that photodegradation efficiency increases by improving the surface properties of AC. The CaO/AC/ZnO nanocomposite exhibited a 96.7% removal efficiency of MB following 120 min of visible light radiation exposure. Therefore, the CaO/AC/ZnO nanocomposite has a promising opportunity to function as a versatile and effective photocatalyst for photodegradation of organic dyes in wastewater.

Amine functionalized graphene oxide decorated with ZnO-WO3 nanocomposites for remediation of organic dye from wastewater

Photocatalytic degradation is as an efficient technique to eradicate toxic chemical pollutants from contaminated water sources. However, the selectivity and photocatalytic activity are the challenging targets to explore the new photocatalysts. Therefore, our research goal is to develop a suitable photocatalyst to satisfy the recent photocatalytic degradation demand. In this work, amine functionalized graphene oxide (NH2-GO) supported heterojunction ternary novel nanocomposites (NH2-GO/ZnO-WO3) were prepared via simple solvothermal method. Structural and morphological investigations of the prepared composites are systematically observed by Field Emission Scanning Electron Spectroscopy (FE-SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Ultraviolet–Visible (UV–vis) Spectroscopy. FT-IR analysis confirmed the effective functionalization of amine on graphene oxide. The XRD results indicated that the prepared nanocomposites were free from any impurities and the binary composite (NH2-GO/ZnO) showed hexagonal wurtzite structure, whereas the ternary composite (NH2-GO/ZnO-WO3) exhibited mix crystal structure of monoclinic and hexagonal phase of WO3 and ZnO, respectively. The synthesized ternary photocatalyst (NH2-GO/ZnO-WO3) demonstrated superior photocatalytic efficiency towards various organic dyes such as cationic dye methylene blue (MB, 85.89%) and anionic dye methyl orange (MO, 60.98%) compared to binary photocatalyst (NH2-GO/ZnO) that showed only 52.28% of MB and 25.8% of MO dye degradation under UV light irradiation. The enhanced photocatalytic performance was mainly due to the low recombination rate of photogenerated electron-hole pair, narrow band gap, and large surface area of ternary composite. The presence of lone pair electrons in amino group provides a negative-charged surface composite resulting good interaction with cationic dye is the key to upgrade the photocatalytic performance. The ternary nanocomposite NH2-GO/ZnO-WO3 has the capacity to be a competent and acceptable photocatalyst for the photodegradation of organic dyes used in industries.

Biogenic silver nanoparticles of Moringa oleifera leaf extract: Characterization and photocatalytic application

Abstract The current study proposed a novel simple and environmentally friendly approach for producing silver nanoparticles (AgNPs) using an extract of Moringa oleifera leaves (MOL) and optimizing the different experimental factors required for the formation and stability of AgNPs. The formation of nanoparticles was confirmed by a color change from yellow to reddish-brown with a surface plasmon resonance band at 412 nm. The morphology, size, and elemental composition of AgNPs were investigated by zeta potential dynamic light scattering, field emission scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, and transmission electron microscopy analysis, which showed crystalline and spherical AgNPs. The identification of functional groups was supported by Fourier-transform infrared spectroscopy. The photocatalytic activities of AgNPs were assessed in the degradation of organic Malachite green (MG) dye in the aqueous solution. Two kinetic adsorption models, the pseudo-first-order model and the pseudo-second-order model, and three isotherm models, the Langmuir, Freundlich, and Temkin, were used to mathematically characterize the MG degradation process. The pseudo-second-order kinetics and the Freundlich isotherm model were found to be in good agreement with the experimental data. As a result of their synergistic interaction with the MOL extract solution, the photocatalytic activity of AgNPs increases and they can successfully adapt to the photodegradation of organic dyes in industrial effluents.

Coaxial Electrospun Porous Core-Shell Nanofibrous Membranes for Photodegradation of Organic Dyes.

In this study, a series of AgCl/ZnO-loaded nanofibrous membranes were prepared using coaxial electrospinning. Their physical and chemical characteristics were evaluated by SEM, TEM, XRD, XPS, IR, PL, and UV-visible spectrometer, and the photocatalytic experiments using methylene blue (MB) as a model pollutant. The formation of AgCl/ZnO heterojunction and the structure of core-shell nanofibers with porous shell layer were confirmed. AgCl/ZnO photocatalysts were also effectively loaded onto the surfaces of the porous core-shell nanofibers. The results of photocatalytic experiments revealed that the AgCl/ZnO (MAgCl:MZnO = 5:5)-loaded nanofibrous membrane achieved a degradation efficiency of 98% in just 70 min and maintained a photocatalytic efficiency exceeding 95% over the first five experimental cycles, which successfully addressed the issues of photocatalytic efficiency loss during the photodegradation of MB with AgCl/ZnO nanoparticles as photocatalyst. The photodegradation mechanism was also researched and proposed.

Gold nanoparticles-decorated MoS2 grown on ZnO nanorod array for sensitive SERS detection and efficient photodegradation of organic dye

Gold nanoparticles-decorated MoS2 grown on ZnO nanorod array for sensitive SERS detection and efficient photodegradation of organic dye

Statement of Retraction: Layered bifuncational Co(II) coordination polymer for photodegradation of organic dyes and anti-osteoporosis activity by activating wnt/β-catenin/PPARγ pathway in BMSCs

Statement of Retraction: Layered bifuncational Co(II) coordination polymer for photodegradation of organic dyes and anti-osteoporosis activity by activating wnt/β-catenin/PPARγ pathway in BMSCs

Silicotungstic acid supported on Bi-based MOF-derived metal oxide for photodegradation of organic dyes

Abstract In this article, Bi-based metal–organic framework-supported silicotungstic acid (STA) was synthesized by a simple hydrothermal method and used as a precursor for the preparation of the Bi-based MOF-derived catalyst (STA@C-Bi-BDC). Using a combination of FTIR, XRD, SEM-EDS, N2 adsorption–desorption, TG, UV-Vis DRS, and XPS techniques, the successful immobilization of STA groups on Bi-MOF-derived C-Bi-BDC was assessed. Furthermore, the photocatalytic performance of the as-prepared catalysts was investigated in the degradation of the RhB dye process under visible light. Within 120 min of visible light exposure, the high degradation rate of RhB (92.7%) by STA@C-Bi-BDC system was achieved, which was a lot larger than the STA (39.4%), C-Bi-BDC (59.2%), and STA@Bi-BDC (74.0%) system, and cyclic experiments exhibit that the STA@C-Bi-BDC is a relatively stable photocatalyst. More importantly, the catalyst shows high applicability for the degradation of other dyes. This study reveals a comprehensive strategy for the design of efficient Bi-based MOF-derived photocatalyst for organic dye-based wastewater treatment.

An efficient polymer supported Fenton type catalyst for photodegradation of organic dyes

The catalytic potential of a novel polymer-supported iron complex (mPAN-Fe) prepared by immobilizing FeCl3 on hydrazine modified polyacrylonitrile (mPAN) is evaluated for the degradation of organic dyes. The prepared complex was characterized using FTIR, XRD, SEM, ICP-MS and DRS/UV analyses. It was found that this complex can acts as an effective heterogeneous catalyst for the photodegradation of methylene blue, methyl orange, and Rhodamine-6G in presence of hydrogen peroxide as an oxidant. The effects of reaction parameters such as concentration of the catalyst, concentration of oxidant, concentration of the dye and pH of the medium on the photodegradation of methylene blue were also studied. The photodegradation of methylene blue was found to be 99 % within 70 min. Moreover, this catalyst exhibited excellent reusability up to 6 cycles for photocatalytic degradation under optimised conditions without significantly losing its activity. The catalyst was also found to be effective for the photodegrdation of methyl orange and Rhodamine-6G. A possible mechanism of photocatalysis under the reaction conditions has been proposed. This is the first study involving a hydrazine-modified PAN-supported iron catalyst towards greener and efficient photocatalysis.

Efficient treatment of oily wastewater, antibacterial activity, and photodegradation of organic dyes using biosynthesized Ag@Fe3O4 nanocomposite.

A significant waste (e.g., high oil content and pollutants such as heavy metals, dyes, and microbial contaminants) in water is generated during crude oil extraction and industrial processes, which poses environmental challenges. This study explores the potential of Ag@Fe3O4 nanocomposite (NC) biosynthesized using the aqueous leaf extract of Laurus nobilis for the treatment of oily wastewater. The NC was characterized using ultraviolet-visible (UV-Vis) spectrophotometry, Scanning Electron Microscopy (SEM), Fourier Transformed Infrared (FTIR) and X-Ray Diffraction (XRD) spectroscopies. The crystalline structure of the NC was determined to be face-centered cubic with an average size of 42 nm. Ag@Fe3O4 NC exhibited significant degradation (96.8%, 90.1%, and 93.8%) of Rose Bengal (RB), Methylene Blue (MB), and Toluidine Blue (TB), respectively, through a reduction reaction lasting 120 min at a dye concentration of 10 mg/L. The observed reaction kinetics followed a pseudo-first-order model, with rate constants (k-values) of 0.0284 min-1, 0.0189 min-1, and 0.0212 min-1 for RB, MB, and TB, respectively. The fast degradation rate can be attributed to the low band gap (1.9 eV) of Ag@Fe3O4 NC. The NC elicited an impressive effectiveness (99-100%, 98.0%, and 91.8% within 30 min) in removing, under sunlight irradiation, several heavy metals, total petroleum hydrocarbons (TPH), and total suspended solids (TSS) from the oily water samples. Furthermore, Ag@Fe3O4 NC displayed potent antibacterial properties and a good biocompatibility. These findings contribute to the development of efficient and cost-effective methods for wastewater treatment and environmental remediation.

Efficient photodegradation of organic dyes from industrial wastewater using novel Ni-decorated g-C3N4-TiO2 photocatalysts

Efficient photodegradation of organic dyes from industrial wastewater using novel Ni-decorated g-C3N4-TiO2 photocatalysts

Construction of magnetically recyclable Fe3O4/hTiO2/g-C3N4 composites for solar photocatalytic degradation of organic pollutants: Study on the performance and mechanism insight

Magnetically separable Fe3O4/hTiO2/g-C3N4 composites were successfully constructed through coating polymethylacrylic acid sacrificial interlayer by the reflux-precipitation polymerization and subsequent TiO2 outer layer by sol–gel method over magnetic Fe3O4 nanospheres, calcining process and forming composites with g-C3N4 in sequence. The formation mechanism of unique composites was proved by TEM, XPS, VSM, XRD and EDX mapping characterization. Their photocatalytic activity was investigated by the solar photodegradation of organic dyes. The results revealed the photocatalytic performance of Fe3O4/hTiO2/g-C3N4 for degrading methylene blue (95.0 %, 120 min) under simulated sunlight irradiation (Xe lamp, 500 W) was much better than g-C3N4 (71.1 %, 120 min) and Fe3O4/hTiO2 (40.3 %, 120 min). The boosted property is presumably ascribed to the synergetic interaction of multiple components and effective separation of the photoproduced electron-hole pairs between g-C3N4 and TiO2, which was verified using photocurrent and EIS analysis. On the basis of the scavenging studies of radicals (h+, •O2– and •OH), the mechanism of the boosted photocatalytic performance was put forward. The degradation pathways of methylene blue were also proposed by identifying reaction intermediates produced during photocatalysis. More significantly, the composites presented excellent magnetic responsive property owing to the magnetic Fe3O4. The superior recyclability was confirmed by cyclical photocatalytic experiments with the help of an external magnet, which is crucial for the sustainable and green application of photocatalysts.

AgTNP@TiO2@Ag core-satellite composites for sensitive sensing and in situ monitoring photodegradation of organic dyes by portable Raman spectrometer

The development of sensitive, reliable, and robust substrates for surface-enhanced Raman spectroscopy (SERS) heavily relies on the creation of numerous hot spots. In this study, we propose a simple approach to fabricate core-satellite composites composed of AgTNP@TiO2@Ag, where Ag triangular nanoplates (AgTNPs) act as the cores, TiO2 serves as the interlayer, and Ag nanoparticles are deposited around them to form Ag satellites. By adjusting the amount of AgNO3, we precisely control the coverage of Ag nanoparticles on AgTNP@TiO2@Ag, thus fine-tuning their SERS sensitivity. Various characterization techniques were employed to examine their composition, morphology, and crystal structure. Thanks to the abundant hot spots created by the Ag satellites, these composites exhibit significantly enhanced SERS sensitivity and they demonstrate the capability to detect methylene blue (MB) at a concentration of 10−10 M by portable Raman spectrometer. Moreover, the AgTNP@TiO2@Ag composites effectively enable in situ SERS monitoring of the photodegradation reaction of MB. Overall, the novel AgTNP@TiO2@Ag composites prepared in this study exhibit high SERS sensitivity and excellent photocatalytic performance, making them highly valuable for environmental detection and ecological restoration purposes.

AgVO3/Ag6Si2O7 nanocomposites with enhancing visible-light driven photocatalysis performance

The AgVO3/Ag6Si2O7 nanocomposite was developed via the coprecipitation method. After being composited, these two nanostructures developed a heterojunction form. The DRS spectra suggested that these nanocomposites with different ratios possessed suitable bandgap, therefore could strongly absorb visible light. The EIS and Mott−Schottky plot curves show that the AgVO3 structure was n-type conductivity semiconductor, while the Ag6Si2O7 structure was p-type conductivity, and these two semiconductors could form the p-n heterojunction nanostructure. The AgVO3/Ag6Si2O7 nanocomposite possess higher photogenerated carrier transfer efficiency and stability of the photogenerated carriers. The organic dye photodegradation activity studies suggested that the AgSV-12 exhibited the best photocatalysis effectivity, and showed good photodegradation activity to other organic dyes. The ESR and reactive species quenchers study suggested that the reactive species that oxidized the organic dyes were photogenerated holes, •O2− and •OH, and the photogenerated holes played the essential factor. Finally, the photocatalysis mechanism and process were presumed as the p-n heterojunction mechanism.

Catalytic properties of CeO2/TiO2 synthesized by different methods towards the organic dye photodegradation and NH3 selected catalytic removal of NOx

In this work, three synthesis methods including photo-chemical, precipitation and hydrothermal were applied for synthesizing CeO2/TiO2 catalysts, and the catalytic performance including photodegradation degrees for organic pollutant and ammonia selective catalytic reduction (NH3-SCR) for NO removal were investigated. It was found that the photo-chemical synthesized CeO2-TiO2-PC exhibited the best photodegradation ability for methylene blue (MB), which had the degradation ratio of 91.21% and was approximately 23.92% higher than that with the matrix of rutile TiO2. The formed Ce-Ti heterojunction enhanced the separation of e −/h + and further promoted the photocatalytic properties. Moreover, the CeO2-TiO2-PC, and the CeO2-TiO2-P which synthesized by the precipitation method showed better NH3-SCR properties than that of hydrothermal synthesized CeO2-TiO2-H below 300 °C, while the CeO2-TiO2-H owned an outstanding NH3-SCR performance above 300 °C. The difference on the NH3-SCR properties may be major attributed to the acid sites, pore structures and surface areas on the surface of different catalysts.