Dye Degradation Research Articles

Cerium doped ZnO nanostructured photocatalyst for the degradation of multiple dyes

Cerium doped ZnO nanostructured photocatalyst for the degradation of multiple dyes

Multifunctional Applications of Gd‐Doped ZnO Nanoparticles Prepared Easily by the Coprecipitation Method

AbstractThe present work involves the preparation of pure ZnO and gadolinium‐doped ZnO nanoparticles with the general formula GdxZn1−xO (X = 0–0.05) by wet chemical coprecipitation technique. XRD outcomes confirmed that these nanoparticles exhibited a hexagonal wurtzite structure of zinc oxide lacking any secondary phase. The calculated average crystallite size declined from 33 to 28 nm. Through SEM analysis, the shape and morphology of the sample were determined, which showed nanoflakes‐like structures, and EDS analysis confirmed the elemental composition of Gd‐doped ZnO nanoparticles. UV–vis DRS spectral studies indicate good optical capabilities with a decline in the bandgap from 3.4 to 2.6 eV with an incline in doping concentration. Photoluminescence studies exhibited a green emission peak at 378 nm. Additionally, photodegradation of these nanoparticles was assessed through degradation of MB dye, which showed 94% of dye degradation. Synthesized nanoparticles show good electrochemical performance in CV studies. Pure ZnO and Gd‐ZnO were examined against Gram‐positive Enterococcus faecalis and Gram‐negative Escherichia coli bacteria, and it was initiated that the zone of inhibition of antibacterial activity improved with gadolinium doping compared to the pure ZnO nanoparticles.

Synthesis and characterization of ZnO nanorods via hydrothermal route for wastewater recycling

In this work, highly efficient ZnO nanorods (NRs) were prepared using an easy and costeffective hydrothermal process. The Synthesized ZnO NR have been analyzed for their structure, morphology, and optical characteristics using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier Transform Infrared (FTIR), and ultraviolet-visible (UV-visible) spectroscopy, respectively. Additionally, a test is conducted on the ZnO nanorod's photocatalytic efficiency towards the degradation of certain dyes, Methylene Blue (MB) and Methyl Orange (MO). The FESEM investigation revealed that the ZnO nanostructures show nanorods with varying diameters (needle-like shape) with an estimated size of (10 to 20) µm. According to the XRD examination, the NRs had a hexagonal-shaped wurtzite pattern, exhibiting an average crystallite diameter of about 50 nm. FTIR spectra confirmed that functional groups from the substance being extracted were present in the ZnO NRs. The band-gap value of 3.37 eV was determined through the TAUC plot model from the ultraviolet-visible spectrum data. In the presence of as-synthesized ZnO NRs, the MO dye degraded by 100 percent in 46 minutes, but the MB dye significantly degraded by approximately 100 % in 20 minutes with high degradation rate constants kMO = 0.086 min-1 and kMB = 0.180 min-1, respectively.

Enhanced Fenton Degradation of Methylene Blue Dye Using CuFe2O4/Fe2O3/CHCP Heterogeneous Catalyst for Superior H2O2 Activation

Enhanced Fenton Degradation of Methylene Blue Dye Using CuFe2O4/Fe2O3/CHCP Heterogeneous Catalyst for Superior H2O2 Activation

Annealing effects on bio-fabricated nickel oxide nanoparticles for environmental remediation: Photocatalytic dye degradation and antimicrobial activity

Annealing effects on bio-fabricated nickel oxide nanoparticles for environmental remediation: Photocatalytic dye degradation and antimicrobial activity

Fabrication of biogenic CDs integrated TiO2 nano-heterojunction for the assessment of visible light mediated photocatalytic dye degradation.

Fabrication of biogenic CDs integrated TiO2 nano-heterojunction for the assessment of visible light mediated photocatalytic dye degradation.

Optimizing photocatalysis: Tuning europium concentration in zinc oxide nanoparticles for superior performance

This work reports, improved photo catalytic performance of ZnO by band gap engineering via Eu doping (0.5–2.0 %). Single phase wurtzite structure of sol gel derived ZnO and Eu (0.5–2.0 %) doped ZnO are confirmed by XRD, FTIR and Raman spectra. Slight variation in structural parameter, FTIR stretching mode at 677 cm−1 and Raman E2 peak position indicate substitution of Eu+3 in ZnO. Calculated band gap decreases [3.05-2.89] with Eu concentration due to generation of charge trap level. Dye degradation of MO improved in Eu doped ZnO as compare to ZnO. The catalytic effectiveness is clearly shown by significant breakdown of a commonly used MO dye (at a concentration of 120 mg l−1). ZnO: Eu 2 % has a remarkable clearance rate of 99.37 %, which is explained by pseudo-first-order kinetics. The increase in oxygen radical ion concentration due to presence of Eu2O3 impurity phase in Eu 2 % doped ZnO supports MO degradation mechanism.

Five novel Pb/Zn/Co metal-organic frameworks using 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene and carboxylate ligands: Synthesis, characterization, DFT calculation and catalytic PMS degradation of RhB

Five new metal-organic frameworks (MOFs), namely {Pb(atpt)(3-bpd)0.5}n (1); {Co(cbz)2(3-bpd)(H2O)2·2H2O}n (2); {Co(imdc)(3-bpd)(H2O)·H2O}n (3); {Co(tdca)(3-bpd)(H2O)2·DMF}n (4); {Zn(tdca)(3-bpd)(H2O)2·DMF}n (5), were assembled with metal ions Pb²⁺, Zn²⁺, and Co²⁺ using 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (3-bpd) as the main ligand, combined with 2-aminoterephthalic acid (H2atpt), 4-cyanobenzoic acid (Hcbz), 4,5-imidazoledicarboxylic acid (H2imdc), and thiophene-2,5-dicarboxylic acid (H2tdca) as auxiliary ligands via hydro/solvothermal methods. Their molecular structures were analyzed by single-crystal X-ray diffraction and characterized by FT-IR and PXRD. Complex 1 has a three-dimensional structure with a hepta-coordinated, semi-directed {PbNO6} metal center. The central metal ions in complexes 2–5 exhibit a six-coordinated {MN2O4} (M = Co or Zn) octahedral geometry. In complex 2, the carboxylate ligand does not function as a bridging ligand, resulting in a 1D chain structure, while complexes 3- 5 extend into 2D layered structures. Thermogravimetric analysis indicates good thermal stability for complexes 1–5. Then, the prepared complexes were used as catalysts to degrade Rhodamine B (RhB) during the monopersulfate (PMS) activation. Complexes 3 and 4 demonstrated significant efficiency, achieving degradation rates of 93.61 % and 98.56 % within 10 min. Radical scavenging experiments and EPR analysis identified that the activation of PMS for dye degradation by the two catalysts occurs through both radical and non-radical pathways, with SO4•− and •OH radicals being the dominant species. Density functional theory (DFT) calculations explained the superior catalytic performance of complex 4 compared to complex 3.

Biochar as an Enzyme Immobilization Support and Its Application for Dye Degradation

Wastewaters generated by the textile industry often contain significant amounts of harmful (carcinogenic and mutagenic) cationic dyes, whose efficient removal is of crucial importance. This study investigates the laccase immobilization on biochar obtained from sour cherry stones (SCS-B), as a cost effective adsorbent, and evaluates its application for brilliant green (BG) degradation. The successful immobilization of laccase on biochar was achieved via adsorption and confirmed using scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). An immobilization efficiency of 66% was achieved using 0.274 U/mL of laccase at pH 5 and a temperature of 40 °C. The adsorption kinetics of laccase followed a pseudo-second-order model, indicating that chemical adsorption plays a significant role in the immobilization process. The BG degradation by immobilized system was further optimized by evaluating effects of pH, temperature, dye concentration, and contact time. More than 92% of BG (50 mg/L) was removed within 4 h at pH 5 and temperature of 30 °C. These findings suggest that SCS-B can effectively be used as an enzyme carrier and be further utilized for the removal of emerging pollutants, positioning it as a sustainable solution for wastewater treatment.

Synthesis of nanostructured microspheres of NiCoO2 for photocatalytic dye degradation

Synthesis of nanostructured microspheres of NiCoO2 for photocatalytic dye degradation

Breaking New Grounds: solid-state synthesis of TiO2 – La2O3 – CuO Nanocomposites for degrading Brilliant Green dye under Visible Light

Environmental pollution, particularly from industrial dyes and chemicals, poses a significant threat to ecosystems and human health. Traditional pollution mitigation methods are often inefficient and costly. Photocatalysis has emerged as a promising solution for degrading pollutants using light energy. Titanium dioxide (TiO2) is a widely studied photocatalyst due to its stability, non-toxicity, and strong oxidative power. However, its efficiency is limited by a wide bandgap, restricting absorption to the UV region, and rapid electron-hole recombination. To address these limitations, doping TiO2 with materials like La2O3 and CuO has been explored to enhance its photocatalytic activity under visible light. This study investigates the enhancement of TiO2 nanocomposites by incorporating La2O3 and CuO. X-ray diffraction (XRD) revealed that the nanocomposites retained TiO2's anatase and rutile phases with improved crystallinity. Scanning electron microscopy (SEM) displayed spherical nanoparticles forming agglomerates, typically due to high surface energy. Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of La and Cu in the TiO2 matrix. Fourier-transform infrared (FTIR) spectroscopy identified characteristic vibrational modes of Ti–O, La–O, and Cu–O bonds, suggesting strong chemical interactions between dopants and TiO2 lattice. Ultraviolet-visible (UV-Vis) spectroscopy showed a red shift in absorption spectra with La2O3 and CuO addition, reducing the bandgap energy from 3.23 eV (pure TiO2) to 2.27 eV for the TiO2–0.1La2O3–0.2CuO composite. Photoluminescence (PL) spectroscopy indicated improved charge separation and reduced electron-hole recombination rates in the synthesized nanocomposites. Photocatalytic performance was evaluated by degrading Brilliant Green (BG) dye under visible light. The TiO2–0.1La2O3–0.2CuO (TLC0.2) nanocomposite achieved a maximum dye degradation of over 95% after 204 minutes under optimal conditions (C0 = 17 mg/L and a S/L ratio of 1 g/L). Adding the inorganic agent Na2SO4 to this process significantly enhanced photocatalytic activity, increasing degradation from 56% to 95% after 180 min of visible light irradiation under C0 = 20 mg/L and S/L = 0.5 g/L conditions, as it shows a high stability after six reuse cycles. In conclusion, La2O3 and CuO doping significantly enhance TiO2 nanocomposites' crystalline structure, morphology, optical properties, and photocatalytic efficiency, demonstrating their potential for environmental remediation and solar energy conversion.

Green synthesis of zinc oxide nanoparticles doped Leucas aspera leaf extract and its photocatalytic applications

Zinc oxide (ZnO) nanoparticles have been produced from the leaf extract of Leucas aspera by utilising a straight forward co-precipitation technique in a green synthesis strategy. The produced nanoparticles are examined by photocatalytic analysis, FTIR, XRD, UV–visible, and SEM. ZnO-related distinctive peaks were visible in the FTIR spectra. The XRD investigation verifies that the produced nanoparticles have a hexagonal crystal structure. Doped ZnO utilising leaf extract has surface morphology that is practically spherical in shape and has minimal aggregation, according to SEM analysis. ZnO-LA composite's photocatalytic dye degradation effectiveness against visible light irradiations is approximately 83%.

Coupling pyroelectric fields and donor doping to adjust Curie temperature and band structure to access to highly efficient BaTiO3 photoelectrodes for dye degradation

Coupling pyroelectric fields and donor doping to adjust Curie temperature and band structure to access to highly efficient BaTiO3 photoelectrodes for dye degradation

Fe3C@Fe decorated carbonized wood Fiber catalyst for organic dyes degradation: Preparation, characterization and mechanism

The extensive use of organic dyes has led to significant water pollution. Using lignocellulosic waste as a precursor for catalysts preparation for sewage remediation presents an effective alternative with numerous advantages in sustainability, cost-effectiveness, and environmental compatibility. In this work, wood fiber waste collected from wood processing plants was decorated with Prussian blue (PB) and then annealed to produce carbonized wood fiber catalyst (Fe3C@Fe-CB). In the presence of peroxymonosulfate (PMS), the prepared catalyst could achieve over 98.69 % efficiency in degrading methylene blue (MB) solutions (20 mg/L) in 60 min across a pH range of 3 to 11. Electrochemical test and electron paramagnetic resonance (EPR) analysis respectively verified that electron transfer pathway and radical pathway were the key factors for the degradation of MB. Cyclic degradation tests demonstrated that the degradation efficiency remained above 93.67 % after five recycling experiments. Moreover, the used magnetic catalyst can be easily recycled by magnet. This study proposed a facile and sustainable carbonized wood fiber catalyst decorated by Fe3C@Fe-CB, which could realize efficient elimination of organic dyes. Moreover, we offered a novel choice for dyes-polluted water treatment and paving a new route for converting low-value lignocellulosic waste to high-value utilizations.

Preparation and investigation of physicochemical properties of g-C3N4/LaCoO3 heterostructure for photocatalytic dye degradation

Photocatalytic decomposition of pollutant is the most optimal approach for the wastewater remediation. Nevertheless, the development of a catalyst that is both cost-effective and extraordinarily active remains a substantial challenge. The g-C3N4/LaCoO3 heterostructure were prepared by different weight percentages of g-C3N4 (15, 30, 45, 60, and 75 wt%). The g-C3N4 and LaCoO3 were exhibits hexagonal and rhombohedral crystal structure respectively. The g-C3N4/LaCoO3 heterostructure exhibits tiny particles were anchored over the coarse like structure. The g-C3N4/LaCoO3 heterostructure promote visible light harvest and inhibit charge carrier recombination than the bare LaCoO3 and g-C3N4 and which helps to enhance the organic pollutant elimination performances. The g-C3N4/LaCoO3 heterojunction exhibits superior methylene blue degradation when compared to bare LaCoO3 and g-C3N4. Furthermore, the composite of LaCoO3/g-C3N4–60 wt% exhibits higher photocatalytic activity and exceptional stability were observed under visible light irradiation.

Metallo‐Surfactant Complex‐Assisted Biomimetic Synthesis of Silver Nanoparticles: Exploring Relativistic Effects in Catalytic and Sensing Applications

AbstractA biological reduction method for silver nanoparticles was employed using Cassia alata extract from plant leaves, which functions as a reducing agent and the metallo‐surfactant [Co(dqn)2(C12H27N)2]3+ (dqn = dipyrido[3,2‐f:2′,3′‐h]‐quinoxaline; C12H27N)2 = dodecylamine) acting as both stabilizing and capping agent. The ratio of Ag nanoparticles (AgNPs) formation was adjusted to be equal to the amount of AgNO3, along with variations in the amount of plant leaf extract, the metallo‐surfactant, pH, surrounding temperature, and the length of interaction periods. High‐resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FE‐SEM), energy‐dispersive spectroscopy (EDS), and energy‐dispersive X‐ray analysis (EDAX) were used to confirm the formation of AgNPs. The infrared results indicate the presence of hydroxyl, amine, and carboxylate groups in the extract plays a crucial role in the reduction process. Additionally, the metallo‐surfactant acts as a capping agent for the silver nanoparticles, preventing agglomeration. By adjusting the acidity of the solution and the quantity of the additive metallo‐surface active agent utilized, the size of AgNPs can be precisely regulated. The relativistic effects observed in this metallo‐surfactant‐assisted silver nanoparticle demonstrate excellent reduction capabilities for nitro compounds, effective dye degradation, and mercury sensing applications.

MoS2–CdS Composite Photocatalyst for Dye Degradation: Enhanced Apparent Quantum Yield and Reduced Energy Consumption

AbstractThis study investigates the visible light‐assisted photocatalytic degradation of rhodamine B (Rh B) dye using MoS2–CdS nanocomposite. Two crucial operational parameters, illumination time and the weight ratio of MoS2 to CdS, are systematically examined. Approximately, 91.9% of Rh B solution with a concentration of 10 mg/L is degraded by the MoS2–CdS photocatalyst under 60 min of illumination, with a photocatalyst dosage of 0.5 g/L. The results are consistent with a pseudo‐first‐order kinetic model, wherein the degradation rate constant of CdS increases fourfold after amalgamation with MoS2. The formation of the composite with MoS2 results in 1.72 times increase in the apparent quantum yield and 3.15 times decrease in the electrical energy consumption per order of CdS nanorods under similar experimental conditions. The investigation also comprehensively explores the reactive species responsible for Rh B degradation under visible light in the presence of MoS2–CdS photocatalyst. This analysis confirms that both hydroxyl and superoxide anion radicals play a dominant role in Rh B degradation. These findings underscore the potential practical applications of MoS2–CdS nanorods in eco‐friendly water treatment technologies, offering efficient and sustainable solutions to contemporary environmental challenges.

Design, construction and evaluation of collaborative bio-system of Vibrio fluvialis with Chlorella sorokiniana for treating actual printing and dyeing wastewater

Treating actual printing and dyeing wastewater (APDW) using bacteria/algae collaborative is considered an eco-friendly and cost-effective strategy. In this study, Vibrio fluvialis (V. fluvialis) and Chlorella sorokiniana (C. sorokiniana) were isolated from APDW and used to construct the bacteria/algae collaborative treatment system (BACTS) for treating APDW. The results showed that the V. fluvialis / C. sorokiniana collaborative treatment could achieve removal rates of 87.31 % for TP, 73.23 % for COD, and 35 % for dyes under the optimized conditions (V. fluvialis first added, C. sorokiniana followed, V. fluvialis / C. sorokiniana inoculation ratio of 1:2, pH 6.5 and light intensity 8,000 Lux). The APDW water quality improved 55.6 % after the V. fluvialis / C. sorokiniana collaborative treatment. Additionally, the collaborative system generated a significant amount of high-value products (27.63 % lipid yield, 81.1 mg/g polysaccharide and 16.62 mg/g protein). The transcriptome analysis demonstrated that the expression of various enzymes such as laccases, peroxidases and azoreductases, etc. related pathways in V. fluvialis / C. sorokiniana involved in textile dyes degradation and biotransformation. This study provides an efficient and low-cost treatment method for APDW through a novel synergistic biological system of bacteria and algae.

Development of flexible and mesoporous CdS/ZnS/PVDF nanocomposites with remarkable organic dye degradation performance under natural sunlight

The engineering of polymer-based nanocomposites is a highly promising strategy for improving both the efficiency and stability of catalysts used in wastewater treatment. In this work, we explore the efficacy of flexible CdS/ZnS/PVDF nanocomposite films towards degradation of Malachite Green dye under low energy visible light and ambient sunlight. Films with varying weight percentage of CdS/ZnS nanofillers (0 %, 5 %, 10 %, 15 %, 20 %) were successfully prepared by solution casting method and the physiochemical properties were characterized using various techniques such as XRD, SEM, AFM, EDX, BET, UV–Vis DRS and FTIR. Pore diameter of 5.5 nm was observed, indicating that CdS/ZnS is mesoporous in nature. Under the optimum photocatalytic condition of 15 ppm dye concentration and pH 9, 15 wt% CdS/ZnS/PVDF showed the maximum photodegradation efficiency of 93.5 % in 30 min. The sample exhibited excellent reusability for five consecutive runs of the experiments which show a degradation percentage of 92.1 % in the fifth run and the scavenging study established that superoxide radicals play the major role in the photodegradation process. The experiments under natural sunlight on three separate days showed a remarkable photodegradation performance of 89 %, 93.4 % and 93.6 % highlighting the potential of CdS/ZnS/PVDF nanocomposites for sustainable wastewater treatment under natural sunlight.

Polydopamine‐Mediated Gold Nanostructure‐Decorated Electrospun Polycaprolactone Fibers for Photocatalytic Dye Degradation

AbstractMetallic nanoparticle (NP)‐decorated electrospun micro/nanofibers as an ideal photocatalytic system for the degradation of organic dyes may provide unique advantages in terms of 3D morphology with high surface area, well‐controlled porosity, low cost, good interconnectivity, and excellent flexibility. However, novel, flexible, low‐cost, and efficient fabrication methods are still demanded to obtain photocatalytic activity. In this report, for the first time, we propose gold NP (AuNP)‐decorated electrospun poly(Ɛ‐caprolactone) (PCL) membrane fibers through a conformal thin layer of polydopamine (PDA). Herein, PDA could reduce the Au3+ ions and enable the adsorption of AuNPs without using any reducing agent or seed material. The proposed system could degrade methylene blue after a 6‐h of daylight exposure with a rate constant of 4.83 × 10−3 and 4.64 × 10−3 min−1 for citrate‐stabilized AuNPs and reduction of Au ions cases, respectively. Even after fifth cycle of usage, AuNP‐decorated electrospun fibers showed reasonable catalytic activity without any significant change in their morphology and chemical content. For the case of rhodamine 6G, the same systems provided 55.2% and 64.1% of dye degradation within a 5‐h exposure. The proposed system presents unique advantages regarding control, flexibility, low cost, and efficiency in various catalytic applications.