Photocatalytic Dye Degradation Research Articles

Intrinsically microporous polyimide-based metal-free catalysts for round-the-clock photodegradation of organic pollutants

Photocatalytic degradation of organic pollutants is an essential technology for various environmental applications. However, the effectiveness of most photocatalysts is restricted to light. Herein, we report metal-free catalysts derived from intrinsically microporous polyimide for persistence in photocatalytic degradation of dyes. We systematically investigate the effect of porosity and functionality on photocatalytic efficiency. Both the pristine 4,4′-(hexafluoroisopropylidene)diphthalic anhydride-3,3′-dimethylnaphthidine and its thermally annealed counterpart at 530 °C exhibit high charge storage capabilities, enabling continuous photodegradation in the absence of light. The pre-irradiated catalyst exhibits an approximately 99% degradation of the dye, with a ~40% improvement relative to the non-pre-irradiated sample. We studied the influence of the chemical structure and porosity on the photocatalytic degradation efficiency in darkness by varying the polyimide chemical structure using different diamines. This research underscores the potential of polymers with intrinsic microporosity for application in the continuous degradation of dyes, contributing to the pursuit of cleaner water.

Ultrasonic Assisted Synthesis of CuFe2O4-Ag infused Gum Hydrogels Nanocomposite for photocatalytic Degradation of Organic Dye from Wastewater

Ultrasonic Assisted Synthesis of CuFe2O4-Ag infused Gum Hydrogels Nanocomposite for photocatalytic Degradation of Organic Dye from Wastewater

Mechanistic Insights and Emerging Trends in Photocatalytic Dye Degradation for Wastewater Treatment

AbstractThis review explores advancements, challenges, and considerations in photocatalytic dye degradation for sustainable wastewater treatment. It highlights smart photocatalyst design, visible‐light‐responsive materials, and co‐catalyst engineering, which enhance system efficacy. Despite environmental concerns, the eco‐friendly aspects of photocatalysis offer a promising alternative to traditional methods. Future perspectives emphasize nanotechnology's role in developing effective photocatalysts and integrating visible‐light and solar‐driven systems to meet sustainability goals. Efforts in co‐catalyst engineering and reactor design aim to optimize processes, addressing kinetic and scalability challenges, while economic research focuses on reducing costs to improve competitiveness.

Synthesis and characterization of micro-/nano-α-Fe2O3 for photocatalytic dye degradation.

Photocatalytic activity using micro-/nano-α-Fe2O3 on a large scale was carried out using a sol-gel autocombustion method. A degradation time of 60 min was noted for 50 mg of the catalyst. Post characterization, this catalyst system showed a degradation of about 53% (rate = 2.60 × 10-3 min-1) and 17% (rate = 1.38 × 10-2 min-1) under sunlight and up to 45% (rate = 1.13 × 10-3 min-1) and 7% (rate = 1.20 × 10-2 min-1) under a 400 W UV lamp for rhodamine 6G (R6G) and crystal violet (CV), respectively. Sunlight has a broad spectrum of light; it greatly accelerates the degradation process and creates ideal conditions for the reaction to occur. The rate of photocatalytic dye degradation of α-Fe2O3 without Fenton's reagent was found to be 7.84 × 10-3 min-1 in the presence of external air provided (in the photocatalytic setup) through a bubbler and 3.23 × 10-3 min-1 in the absence of the bubbler.

A New Type of Composite Catalyst α-nBACoPc/SnO2 Synergistic Photo-Catalytic Degradation of Dyes

A New Type of Composite Catalyst α-nBACoPc/SnO2 Synergistic Photo-Catalytic Degradation of Dyes

Green Synthesis of Mn‐Doped ZnO Nanoparticles Using Ipomoea Staphylina Leaf Extract: Characterization and Application of Photocatalytic Dye Degradation, Antibacterial and Antioxidant Activity

AbstractZinc oxide nanoparticles (ZnO NPs) and manganese‐doped zinc oxide nanoparticles (Mn‐ZnO NPs) were synthesized via a cost‐effective green combustion method employing watery leaf extracts from Ipomoea Staphylina. The nanoparticles were thoroughly characterized using FT‐IR, P‐XRD, UV‐DRS, and FE‐SEM with EDX techniques. X‐ray photoelectron spectroscopy (XPS) confirmed the successful doping of Mn in ZnO NPs. Evaluation of photocatalytic efficiency revealed that ZnO NPs degraded 76 % of Congo red dye (CR), while Mn‐doped ZnO NPs exhibited a higher degradation efficiency of 92 %. The photocatalytic performance of Mn‐doped ZnO NPs surpassed that of ZnO NPs, indicating their superior photocatalytic properties. Furthermore, both ZnO and Mn‐doped ZnO NPs displayed notable antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Klebsiella pneumonia. Additionally, Mn‐doped ZnO NPs exhibited significant antioxidant activity, demonstrated by their ability to scavenge 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH⋅) free radicals. These findings suggest that biosynthesized pure and doped NPs using plant extract can be promising candidates for antibacterial and antioxidant applications in biomedical, pharmaceutical, and wastewater treatment fields.

Efficient photocatalytic degradation of crystal violet dye using time-dependent ZnO nano spindle

Photocatalysis, utilizing metal–semiconductor oxides, has emerged as a promising technique for the oxidation of organic molecules due to its efficiency, cost-effectiveness, and eco-friendly nature. This study presents the synthesis and application of time-dependent ZnO nano spindles for the efficient photocatalytic degradation of crystal violet dye. ZnO nanostructures, known for their high photocatalytic activity, were synthesized using a simple and low-cost coprecipitation method, with the spindle morphology being fine-tuned by varying reaction times. The resulting nano spindles were characterized using X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and UV–vis spectroscopy to confirm their structural, morphological, and optical properties. XRD analysis revealed that the ZnO samples possess a hexagonal wurtzite crystal structure with a space group of P63mc. SEM analysis confirmed the formation of spindle-like morphologies, with the synthesized samples measuring just a few nanometers in size. The surface area and porosity of the ZnO samples have been observed by using the Brunauer–Emmett–Teller (BET) analysis. The obtained surface area of all ZnO samples is in the range of 15 to 30 m2g−1. Photocatalytic performance was evaluated under UV light irradiation, demonstrating that the degradation efficiency of CV dye significantly depends on the exposure duration and the morphological attributes of the ZnO nano spindles. The degradation kinetics followed a pseudo-first-order model, with the optimized ZnO nano spindles achieving up to 99 % degradation efficiency within 150 min. This study highlights the potential of time-dependent morphological control in ZnO nanostructures to enhance photocatalytic processes, presenting a viable solution for the treatment of dye-laden wastewater.

Synthesis and characterisation of visible light-responsive Fe-doped BiOCl NPs and their application for the remediation of textile dye by LED irradiation

ABSTRACT In the present research work, Fe-doped bismuth oxychloride (Fe-doped BiOCl) photocatalyst is synthesised through the precipitation technique, and the mineralisation of textile dye is investigated in the presence of light-emitting diode (LEDs) irradiation (400–700 nm). The prepared photocatalysts were characterised through various spectroscopic techniques for the detailed morphological, elemental and surface properties. The UV–vis absorbance maxima of Fe-doped BiOCl by UV-Vis was near 358 nm, while the band gap was 4.8 eV which is comparatively higher than the average value. Fourier transform infrared spectra showed typical bands of Fe doped BiOCl at 506 cm−1, 1601, 2337 and at 3565.0 cm−1. From the X-ray diffraction (XRD) pattern, the crystalline nature of the Fe-doped nanocomposite was confirmed whose calculated crystallite size was 41.12 nm. The major and sharp two theta peaks of XRD were at 11.95°, 24.07°, 25.81°, 32.46°, 33.39°, 36.47°. The microscopic technique showed that the size of the nanocomposite was 200–400 nm which was in the form of small nanosheets. The energy dispersive X-ray spectroscopy (EDS) showed peaks for Bi, O, Cl and Fe 36.91%, 26.48%, 36.37% and 0.24%, respectively, indicating the formation of the nanocomposite. The BET surface area of the Fe-doped BiOCl photocatalyst was 10.224 m2/g, while the pore volume was 0.065 cc/g. Further, the potential of the developed photocatalytic nanocomposite was evaluated for the photocatalytic degradation of the ethyl violet dye from the aqueous solutions. Various optimisation parameters have been discussed, and it has been found that 89% of the dye was degraded in 125 min with a 5.11 × 10−4 s−1 rate constant. The photocatalyst had shown excellent reusability and stability during the degradation of ethyl violet. The photocatalytic activity of Fe-doped BiOCl was compared with other photocatalysts and current literature and exhibited enhanced efficiency.

Green synthesis of Zn-doped TiO2 nanomaterials for photocatalytic degradation of crystal violet and methylene blue dyes under sunlight

Green synthesis of Zn-doped TiO2 nanomaterials for photocatalytic degradation of crystal violet and methylene blue dyes under sunlight

Plant extract mediated synthesis of BiFeO3 nanoparticles for photocatalytic degradation of methylene blue dye

Plant extract mediated synthesis of BiFeO3 nanoparticles for photocatalytic degradation of methylene blue dye

Sol-gel synthesis of Tb-doped lithium-nickel ferrite anchored onto g-C3N4 sheets for efficient photocatalytic degradation of organic dyes

Due to the advancement of industrialization, water pollution has become an alarming global issue. Many organic dyes, such as crystal violet and rhodamine B, present in industrial wastewater are causing severe health problems. Both of these dyes are carcinogenic. For their degradation, ferrites are synthesized in this research. Ferrites have high absorbing potential in visible regions and fast movement of charge carrier species. Therefore, the ferrites are potentially used in photocatalysis to purify contaminated water. Graphitic carbon nitride shows enhanced separation of charges, which lowers the rate of recombination of charge carrier species. Lithium nickel ferrite, lithium nickel ferrite doped with terbium, and its composite with graphitic carbon nitride (g-C3N4) are synthesized by sol-gel and ultra-sonication methods, respectively. The prepared samples are analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), Electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis. The bandgap of LiNiFe2O4 and LiNiTbFe2O4 was 2.35 eV, and 1.87 eV, respectively. LiNiTbFe2O4@g-C3N4 degraded 86 % crystal violet and 83 % rhodamine B in 120 min. The LiNiTbFe2O4@g-C3N4 composite showed the maximum degradation and can be potentially used in wastewater treatment.

Hydrothermal Synthesis, Characterization of Co3Sb4O6F6 and Carbon doped Co3Sb4O6F6 and their Application towards Photocatalytic Dye Degradation, Adsorption, Catalytic Knoevenagel Condensation and Bacterial Disinfection

Single crystals of Co3Sb4O6F6 have been grown by employing hydrothermal techniques. Table sugar was utilized to prepare carbon-doped Co3Sb4O6F6. The objective was to employ Co(II)-based metal oxyfluoride comprising a stereochemically active lone pair (Sb3+) and its carbon-doped analogues for the multifunctional applications. The impact of carbon doping on Co3Sb4O6F6 has been evaluated towards the changes in photocatalytic, catalytic, and adsorbent efficiency. The changes in carbon percentage affect the physical and chemical properties of the host material. A larger percentage of carbon doping turns the photocatalytic ability of the host material into an adsorbent for the removal of dye. The single crystal X-ray diffraction (SCXRD) study reveals that Co3Sb4O6F6 crystallizes into cubic symmetry. However, powder X-ray diffraction (PXRD) study reveals the structural transformation in the carbon-doped Co3Sb4O6F6. It also reduces the band gap energy of the host material, and 4 wt% C@Co3Sb4O6F6 turns out to be an efficient photocatalyst. Large-scale carbon doping (15 wt%) appears to be an effective strategy to increase the surface charge and BET surface area, as consequences adsorption property develops in 15 wt% C@Co3Sb4O6F6/H2O2 for the elimination of methylene blue (MB). This favourable chemical adsorption process occurs with large maximum adsorption capacity (qmax = 58.41169 mg/g), as evident from the Langmuir adsorption isotherm. Scavenger experiment confirms that the photocatalytic activities of the as-synthesised compounds were triggered by the active participation of the hydroxyl radical (.OH). The catalytic efficiencies of both parent and doped compounds are also established for the solvent-free Knoevenagel condensation reaction with 90% yield at moderate temperature. Bacterial disinfection studies by the ‘Disc diffusion method’ confirm that Co3Sb4O6F6 shows better efficiency than the carbon doped compound against both Gram-positive and Gram-negative bacteria.

Biosynthesis of Pt doped Zn bimetallic nanoparticles by using Polygonum glabrum extract for colorimetric, fluorimetric (Ni2+, Hg2+ and Fe2+) ions sensing and photocatalytic degradation of organic dye with electrochemical techniques

In the present study we aimed to explore the biosynthesis and characterization of monometallic platinum nanoparticles (PtNPs), zinc oxide nanoparticles (ZnONPs) are compared to the Pt doped ZnONPs (Pt-ZnONPs) and its sensing, electrochemical, photocatalytic properties. The bimetallic Pt-ZnONPs was synthesized by using Polygonum glabrum leaves extract; it acts as reducing agent and stabilizing agent. The analysis of colorimetric and fluorimertic sensing methods to determine the highly detection of Ni2+, Hg2+ and Fe2+ ions. The optical properties were characterized by UV-visible, FT-IR, XRD, XPS, SEM-EDX and TEM-SAED analysis. The synthesized monometallic PtNPs and ZnONPs are well dispersed spherical and hexagonal particles with sizes ranging from 8 nm to 25 nm. Electrochemical analysis were carried out the synthesized monometallic and bimetallic Pt-ZnONPs oxidation with reduction potentials by using cyclic voltammetry with UV-visible absorption spectroscopy based on band gap energy to calculation of LUMO and HOMO energy levels. The photocatalytic activities with band gap energy 96% for MeB indicated that only Pt doped ZnONPs for bimetallic Pt-ZnONPs nanocatalyst as compared to monometallic PtNPs and ZnONPs for single metal nanocatalyst actions. The highly sensitivity of Ni2+, Hg2+ and Fe2+ ions are combined with synthesized NPs extended to the oxidation-reduction potential for Pt2+ by Zn2+ ions may find sensitivity for trace different metal ions of pollution level with environmental sensing and photocatalytic applications.

The influence of operational factors on the photocatalytic degradation of methylene blue dye in aqueous Sr-Au-ZnO suspensions under UV-A light

Any of several processes that break down dyes, ideally into harmless chemicals, is referred to as industrial dye degradation. Water waste discharges various colors, particularly those used in the textile industry like methyl red and methylene blue, into ecosystems, leading to significant pollution of the water supply. Under UV-A irradiation, the photocatalytic degradation of a commercial heterocyclic aromatic chemical molecule called methylene blue (MB) has been investigated using an aqueous solution of Sr-Au-ZnO as a photocatalyst. Research has been done on how different process characteristics affect the degradation process. For the mineralization of MB dye under UV-A light, it was found that the optimized Sr-Au-ZnO was more effective than commercial catalysts (ZnO and benchmark photocatalyst Degussa P25), single metal dopants (Sr-ZnO, Au-ZnO), and prepared ZnO. The effects of operational parameters, such as the quantity of photocatalyst, dye concentration, and starting pH, on the photo-mineralization of MB are analyzed before optimal values are given. Chemical oxygen demand (COD) measurements have confirmed that MB is mineralized. Using GC-MS analysis, the intermediates produced during photodegradation were predicted, and an appropriate degradation pathway was suggested. This procedure can be used for treating wastewater from sewage since optimized Sr-Au-ZnO is reusable.

Photocatalytic degradation of the remazol red ultra RGB dye using SrFe12O19-Fe3O4 magnetic oxides dispersed in silica: Effect of reduction temperature

Dyes are the most frequently discarded industrial wastes in aquatic ecosystems, among which Remazol Red ultra RGB stands out. In this context, magnetic iron-based catalyst dispersed in silica were prepared by Pechini route as an alternative for the photodegradation of Remazol Red Ultra RGB. The XRD and Mössbauer spectroscopy results indicated the formation of a magnetic material that, after reduction treatment with H2, forms a magnetite phase combined with Sr hexaferrite dispersed in amorphous silica. The TPR-H2 profiles indicated the reduction of Fe3+ to Fe2+ within the considered temperature range, the amount of Fe2+ increased with rising temperature. The SEM images showed sponge-like morphology for the samples. The EDS spectra and mapping confirmed a high uniformity in the distribution of active iron species in the silica. The magnetic measurements showed a lower magnetic signal for the sample reduced at 600 °C, due to the lower magnetic moment of Fe2+ formed after the reduction. The diffuse reflectance spectra showed a main absorption region between 500 and 200 nm and the estimated band-gap values were of 1.4 and 1.9 eV for the reduced sample and the fresh oxide, respectively. The surface charge was obtained via zeta potential, demonstrating good stability under pH changes and reaching a negative potential in the pH range from 2 to 6. The photocatalytic tests showed that the samples with higher content of Fe2+ demonstrated a greater photocatalytic degradation of the Remazol Red Ultra RGB dye, reaching 100 % degradation in 1 h for the solid reduced at 600 °C. A plausible mechanism for the photodegradation of Remazol Red Ultra RGB was proposed, considering the different elementary steps involving the participation of iron sites and the formation of oxidant radicals.

Synergistic effect of strontium oxide–titanium oxide nanocomposites for photocatalytic degradation of malachite green dye

Synergistic effect of strontium oxide–titanium oxide nanocomposites for photocatalytic degradation of malachite green dye

Facile construction of ZnWO4/g-C3N4 heterojunction for the improved photocatalytic degradation of MB, RhB and mixed dyes

This study presents the construction of binary ZnWO4/g-C3N4 nanocomposite via a facile hydrothermal approach to enhance the photocatalytic performance under the visible light irradiation. The proposed ZnWO4/g-C3N4 nanocomposite photocatalyst shows excellent photodegradation towards organic dyes, such as methylene blue (MB) and rhodamine B (RhB). The optimal loading of ZnWO4 and g-C3N4 leads to the synergistic effect which plays a predominant role in inhibiting the fast electron-hole pairs recombination rate at the interface of ZnWO4/g-C3N4 photocatalyst. The degradation rates of MB and RhB is achieved around 92.9 % and 88.8 % under the visible light irradiation for 120 min. According to our findings, the radical quenching experiments suggested that the ●OH radicals played a positive impact in the photodegradation process. Since, our proposed photocatalyst exhibit superior photocatalytic activity towards the individual MB and RhB degradation. The ZnWO4/g-C3N4 photocatalyst were further applied to demonstrate the degradation of mixed dyes (MB and RhB) at an irradiation time of 180 min. In the mixed dye solution, the ZnWO4/g-C3N4 photocatalyst achieved a highest reaction rate of 0.010 min−1 for MB and 0.012 min−1 for RhB with the degradation rate of 87.8 % and 83.3 % for RhB and MB, respectively. For the mixed dyes, the radical quenching experiments confirmed that the ●OH radicals are responsible for the fast photodegradation. Additionally, the practicality of the proposed ZnWO4/g-C3N4 photocatalyst towards the degradation of MB, RhB and the mixed dyes were examined in the tap water samples. Furthermore, the plausible photodegradation mechanism of ZnWO4/g-C3N4 photocatalyst was proposed in detail. This study provides a new insight for the simultaneous degradation of mixed chemical pollutants using our proposed ZnWO4/g-C3N4 photocatalyst.

Enhanced photocatalytic degradation of organic dyes by dual heterojunction of ZnO/NiWO4/V2C MXene

Multiphase composite catalysts can be designed for efficient photocatalytic treatment of organic pollutants in wastewater. Herein, the multiphase ZnO/NiWO4/V2C composite catalysts with dual heterojunction and hierarchically assembled nanoflower structures were constructed via a facile two-step hydrothermal and electrostatic self-assembly method. Utilizing NiWO4 and V2C as co-catalysts, these catalysts effectively degraded cationic dyes, methylene blue (MB) and rhodamine B (RhB) under visible light irradiation. The ZnO/NiWO4/V2C catalyst exhibited higher photocatalytic activity than ZnO in the degradation of MB and RhB, with rate constants of 0.0194 min−1 (a 7.43-fold enhancement) and 0.0176 min−1 (a 3.13-fold enhancement). The higher activity can be attributed to the construction of the double heterojunction using NiWO4 and V2C, which can facilitate efficient electron transport, improve charge separation efficiency, and provide more active sites. After four cycles, the ZnO/NiWO4/V2C catalyst still maintained good stability. Consequently, this work can offer a promising approach for environmental pollution treatment.

Sphere-Like Nb2O5 nanoparticles by waste Brassica oleracea leaf extract for lead removal and photocatalytic degradation of methylene blue dye

Currently, water-soluble pollutants such as hazardous chemicals and pigments create severe environmental hazards. Heavy metals such as lead, chromium, mercury, and arsenic were dangerous to living beings even at very low levels. To overcome this limitation, Nb2O5 nanoparticles were created utilising a novel green approach. Based on plant components, green technique is a low-cost, safe, and environmentally good solution. In the present inquiry, we employ phytonutrients from waste Brassica oleracea leaf juice as a capping and reducing component. The product was evaluated using XRD, FT-IR, UV, SEM, and TEM techniques. The findings showed that the produced Nb2O5 NPs had a sphere-like geometry having a median particle dimension of 9 nm confirmed by XRD analysis. SEM study reveals ultrafine, homogeneous morphological agglomerations and uniform granules in TEM analysis, 10-15 nm particles predicted by crystallography, orthorhombic Nb2O5 (001) planes matching 0.39 nm lattice edge measurement error, and a clearly defined SAED diffract signal implying polycrystalline calcined powder. Excitation absorbance bands at 350 nm may be caused by charged balancing in the Nb–O–Nb architecture increasing oxygen concentration confirmed by UV-Vis analysis. The Nb2O5 nanosphere has a surface area of 120 m2/g, 0.592 cm2/g of pores, and a mean pore dimension of 15.2 nm, determined using Barrett-Joyner-Halenda (BJH). A sequential Adsorption capacities assay shown that it is an effective absorber used to eliminate Pb (II) ions from aqueous solutions. Adsorbents was able to be readily removed from the resultant fluid and recycled repeatedly. The produced Nb2O5 Nanoparticles are capable of removing toxic heavy metals and synthetic colors from polluted waterways.

Effect of solvothermal reaction time on adsorption and photocatalytic activity of spinel ZnFe2O4 nanoparticles

The present investigation explored the impact of solvothermal reaction time on the adsorption properties of synthesized spinel ZnFe2O4 Nanoparticles (ZF NPs) and their photocatalytic activity of Congo Red (CR) dye. The structure, morphology and chemical composition is identified for the synthesized ZF NPs. The reaction times for the solvothermal synthesis of ZF NPs were investigated at time intervals of 6 h and 18 h which denoted as ZF-6 h and ZF-18 h respectively. The XRD confirms the formation of spinel-type ZF-6 h and ZF-18 h with crystallite size of 5.50 nm and 8.36 nm for ZF-6 h and ZF-18 h respectively. The FESEM image of ZF-6 h exhibits microspheres, whereas in ZF-18 h NPs, the microspheres are observed to be deformed. TEM analysis of ZF-6 h revealed that the microspheres were composed of 8–10 nm ZF-NPs. Raman spectroscopy and XPS studies indicate that the reaction time influence the occupancy with 64 % and 32 % of inversion of Zn2+ cations from tetrahedral to octahedral sites in ZF-6 h and ZF-18 h, respectively. The surface area of mesoporous ZF-6 h and ZF-18 h are 138.29 m2/g and 128.41 m2/g respectively as confirmed using BET and BJH technique. The CR dye adsorption capacity of 123.73 mg/g for ZF-6 h is higher compared to ZF-18 h (99.93 mg/g). The maximum dye removal efficiency evaluated for ZF-6 h NPs and ZF-18 h NPs was 87.33 % and 73.09 % respectively upon exposure of natural sunlight. The recyclability study identifies that ZF-6 h NPs remain stable for three degradation cycles. These results indicate that reaction time in solvothermal synthesis is sensitive to the morphology and physicochemical properties of ZF NPs. The enhanced performance of such ZF NPs is attributed to the synergistic effect of adsorption followed by photocatalytic (photo-Fenton) degradation of dyes.