Photocatalytic Degradation Of Azo Dye Research Articles

Synergistic Ag/g-C3N4 H2O2 System for Photocatalytic Degradation of Azo Dyes.

Graphitic carbon nitride (g-C3N4), known for being nontoxic, highly stable, and environmentally friendly, is extensively used in photocatalytic degradation technologies. Silver nanoparticles effectively capture the photogenerated electrons in g-C3N4, enhancing the photocatalytic efficiency. This study primarily focused on synthesizing graphitic carbon nitride via thermal polymerization and depositing noble metal silver onto g-C3N4 through photoreduction. Methyl orange (MO) and methylene blue (MB) were targeted as the pollutants in the photocatalytic experiments under visible light in conjunction with a H2O2 system. The characteristics peaks, structure, and morphology were analyzed using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). g-C3N4 loaded with 6% Ag exhibited superior photocatalytic performance; the photocatalytic fraction of the degraded materials of the MO and MB solutions reached 100% within 70 and 80 min, respectively, upon adding 1 mL and 2 mL of H2O2. ·OH and ·O2- were the primary active free radicals in the dye degradation process within the synergistic system. Stability tests also demonstrated that the photocatalyst maintained good reusability under the synergistic system.

Ultrasound-Assisted Photocatalytic Degradation of Azo Dyes under Visible Light Irradiation Using Polythiophene-Decorated CoFe2O4 Nanohybrids

The present work reports the synthesis of cobalt ferrite and its nanohybrids with polythiophene (PTh) in the weight ratios of 10% and 20%. The ferrite and its nanohybrids were characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy coupled with elemental mapping (Fe-SEM) to confirm the morphology as well as the structure of the synthesized nanohybrids. The nanohybrids were tested for their photocatalytic activity upon modification of PTh against Alizarin Yellow (AY), Congo Red (CR) and Brilliant Blue (BB). Almost 100% degradation was achieved in 30 min using 50 mg of the photocatalyst. The effect of catalyst concentration and dye concentration was also investigated to explore optimum concentration of the photocatalyst required for rapid degradation of the dye. The generation of radicals responsible for degradation was analyzed by radical scavenging experiments and a probable mechanism of degradation was proposed.

Photocatalytic Degradation of Azo Dyes in Aqueous Solution Using TiO2 Doped with rGO/CdS under UV Irradiation

Photocatalytic Degradation of Azo Dyes in Aqueous Solution Using TiO2 Doped with rGO/CdS under UV Irradiation

Investigating AgCl-SnO2 nanocomposite for photocatalytic degradation of azo dye, associated reaction pathways, and its antibacterial activity

Herein, AgCl-SnO2 nanocomposite (NC) fabricated through a facile hydrothermal method exhibit substantial potential as an efficient and economical photocatalyst and bactericidal agent. The formation of spherical AgCl-SnO2 NC was confirmed through PXRD and SEM, with an average crystalline size of 12 nm. DR spectra and Kubelka-Munk function were used to determine the band gaps of AgCl (3.10 eV) and SnO2 (3.48 eV). The synthesized NC achieve successful photocatalytic degradation (98 %) of orange-G (OG) dye within 60 min. The NC’s potential was also elucidated by investigating the role of sacrificial reagents. Formation of •OH free radicals is confirmed from photoluminescence studies using terephthalic acid. The effective degradation of OG dye has been substantiated, resulting in the generation of numerous intermediate products with reduced toxicity, such as substituted phenols and aromatic dicarboxylic compounds. Furthermore, the NC demonstrated excellent efficiency even after six consecutive cycles, indicating its stability, regenerative property, and recyclability. The NC also exhibits significant antimicrobial activity against Escherichia coli.

Magnetic zinc oxide/silica microbeads for the photocatalytic degradation of azo dyes

Photocatalysis is a promising technique for the complete degradation of azo dyes that are present in wastewater. In this work, a new photocatalyst in the form of ZnO/Fe3O4/SiO2 hybrid microbeads was fabricated for the photocatalytic degradation of methylene blue. The microbeads were synthesised through self-assembly and subsequent agglomeration of nanoparticles within an aqueous phase of a water-in-oil emulsion template. Photocatalytic degradation experiments were conducted through exposure of a methylene blue solution to UV light. The hybrid microbeads performed better than ZnO powder at the same initial dye and ZnO concentration because of higher adsorption and degradation. The initial concentration of dye solution and catalyst dosage have a significant impact on the degradation. Higher degradation is seen with lower initial dye concentration and higher catalyst dosage. The presence of magnetic nanoparticles within the beads allows for their full recovery and reuse for degradation experiments. Complete degradation of dye was achieved using the new ZnO/Fe3O4/SiO2 microbeads.

Biogenic synthesis of Co3O4 nanoparticles from Aloe barbadensis extract: Antioxidant and antimicrobial activities, and photocatalytic degradation of azo dyes

The synthesis of Co3O4 nanoparticles (NPs) through biogenic means offers a cost-effective, environmentally friendly, stable, versatile, and biocompatible approach. In this work, we employed Aloe barbadensis Miller leaf extract for the biosynthesis of Co3O4 NPs, leveraging its rich composition of phenolic groups, polysaccharides, enzymes, minerals, vitamins, and various acids. The characterization of the synthesized NPs was performed using XRD, TEM, EDS, FT-IR, TGA-DSC, Raman, XPS, and particle size analysis techniques. Our investigation focuses on evaluating the antioxidant and antimicrobial properties of Co3O4 NPs. Antioxidant activity was assessed through DPPH, ABTS, FRAP, and FICA assays, demonstrating the NPs' ability to scavenge free radicals, reduce ferric ions, and chelate ferrous ions. Antimicrobial testing revealed the effectiveness of NPs against Proteus mirabilis and Staphylococcus aureus. Furthermore, biogenic Co3O4 NPs were utilized as photocatalysts for the degradation of azo dyes (RhB, MB, and CV). Under sunlight exposure for 105 min, biogenic Co3O4 NPs degraded CV dyes by 97.53%. The study also highlighted the remarkable efficiency of azo dye degradation across five cycles of reuse of biogenic Co3O4 NP reuse.

Enhanced visible-light-driven photocatalytic degradation of azo dyes by heteroatom-doped nickel tungstate nanoparticles

Abstract In this study, we conducted the hydrothermal synthesis of cobalt (Co)–doped NiWO4, resulting in the formation of Co–NiWO4 nanoparticles (NPs), followed by calcination at 550℃ for 12 h. Comprehensive analyses were performed to characterize the composition, structure, and morphology of the synthesized material. X-ray diffraction results confirmed the successful inclusion of Co in the NiWO4 lattice, with the presence of characteristic peaks of CoWO4. The crystallite size, determined using the Scherrer equation, was measured to be 22 nm. Using UV-Vis spectroscopy and Tauc’s equation, we calculated the band gap energy (E g) to be 3.75 eV for NiWO4 and 1.75 eV for Co–NiWO4. The potential application of the synthesized material as a photocatalyst was investigated for the degradation of the diazo dye Congo red (CR). Under optimized reaction conditions, Co–NiWO4 NPs demonstrated outstanding efficiency, degrading a total of 95% of CR. The degradation kinetics were well-described by the Langmuir–Hinshelwood (L–H) kinetic model, indicating that photoabsorption played a crucial role in the rate-controlling step. These encouraging results suggest that Co–NiWO4 NPs hold promise as a viable option for addressing other pollutants in various applications.

Ecofriendly alkali metal cations diffusion improves fabrication of mixed-phase titania polymorphs on fixed substrate by chemical vapor deposition (CVD) for photocatalytic degradation of azo dye

Controlling the nanoscale synthesis of semiconductor TiO2 on a fixed substrate has fascinated the curiosity of academics for decades. Synthesis development is required to give an easy-to-control technique and parameters for TiO2 manufacture, leading to advancements in prospective applications such as photocatalysts. This study, mixed-phase TiO2(B)/other titania thin films were synthesized on a fused quartz substrate utilizing a modified Chemical vapor depodition involving alkali-metal ions (Li+, Na+, and K+) solution pre-treatment. It was discovered that different cations promote dramatically varied phases and compositions of thin films. The films had a columnar structure with agglomerated irregular-shaped particles with a mean thickness of 800–2000 nm. Na+ ions can promote TiO2(B) more effectively than K+ ions, however Li+ ions cannot synthesize TiO2(B). The amounts of TiO2(B) in thin films increase with increasing alkali metal (K+ and Na+) concentration. According to experimental and DFT calculations, the hypothesized TiO2(B) production mechanism happened via the meta-stable intermediate alkaline titanate transformation caused by alkali-metal ion diffusion. The mixed phase of TiO2(B) and anatase TiO2 on the fixed substrate (1 × 1 cm2) obtained from Na+ pre-treated procedures showed significant photocatalytic activity for the degradation of methylene blue. K2Ti6O12, Li2TiO3, Rutile TiO2, and Brookite TiO2 phase formations produced by K+ and Li + pretreatment are low activity photocatalysts. Photocatalytic activities were more prevalent in NaOH pre-treated samples (59.1% dye degradation) than in LiOH and KOH pre-treated samples (49.6% and 34.2%, respectively). This revealed that our developed CVD might generate good photocatalytic thin films of mixed-phase TiO2(B)/anatase TiO2 on any substrate, accelerating progress in future applications.

ZnS/CuFe2O4/MXene ternary heterostructure photocatalyst for efficient adsorption and photocatalytic degradation of azo dyes under visible light: Synergistic effect, mechanism, and application

ZnS/CuFe2O4/MXene (ZSCFOM) composite with ternary heterostructures was prepared by solvothermal methods for the first time to effectively adsorb and photodegrade the azo dyes. ZSCFOM mainly adsorbed azo dyes through the hydrogen bonding and electrostatic interactions, with saturated adsorption capacities of 377 mg g−1 for direct brown M and 390 mg g−1 for direct black RN. ZSCFOM exhibited both characteristics of Schott heterostructure and p-n heterostructure, but it is not a simple superposition of the two heterostructures, but rather achieves better photocatalytic property. ZSCFOM performed a higher separation efficiency of electrons and holes than pure CuFe2O4 and pure ZnS. Under visible light, ZSCFOM was more effective in removing the azo dyes than MXene, CuFe2O4, ZnS, CuFe2O4/MXene, ZnS/MXene, and ZnS/CuFe2O4. The migration pathways of photogenerated carriers in ZSCFOM were inferred as that the electrons were concentrated in MXene and conduction band of ZnS, and holes were gathered in valence band of CuFe2O4. MXene served as a cocatalyst to accelerate the separation of electrons and holes. ZSCFOM mainly degraded DBM and DBRN by catalyzing the generation of holes, superoxide radicals, and hydroxyl radicals. The 100% of 0.05 g L−1 azo dyes were removed by ZSCFOM within 30 min from the environmental water systems.

UV Assisted Photocatalytic degradation of Azo dye in Textile Effluent by Advanced Oxidation Processes Using TiO2 Nanoparticles

UV Assisted Photocatalytic degradation of Azo dye in Textile Effluent by Advanced Oxidation Processes Using TiO2 Nanoparticles

Enhanced photocatalytic performance of auto-combusted nanoparticles for photocatalytic degradation of azo dye under sunlight illumination and hydrogen fuel production

In this study, an innovative nanomaterial was synthesized for hydrogen production from methanolysis on sodium borohydride (NaBH4) in order to be a solution for future energy problems. The nanocomposite containing FeCo, which does not contain noble metals, and whose support material is Polyvinylpyrrolidone (PVP), was synthesized by means of a thermal method. TEM, XRD and FTIR characterization methods were used for the analysis of the morphological and chemical structure of the nanocomposite. Nanocomposite particle size was found to be 2.59 nm according to XRD analysis, and 5.45 nm according to TEM analysis for scale of 50 nm. For catalytic properties of nanomaterial in the methanolysis reaction of NaBH4, temperature, catalyst, substrate, and reusability experiments were carried out and kinetic calculations were obtained. Among the activation parameters of FeCo@PVP nanoparticles, turnover frequency, enthalpy, entropy and activation energy were calculated as 3858.9 min−1, 29.39 kJ/mol, −139.7 J/mol.K, and 31.93 kJ/mol, respectively. As a result of the reusability test of the obtained FeCo@PVP nanoparticles catalysts, which was carried out for 4 cycles, the catalytic activity was 77%. Catalytic activity results are given in comparison with the literature. In addition, the photocatalytic activity of FeCo@PVP NPs was evaluated against MB azo dye under solar light irradiation for 75 min and was found to be as 94%.

Effect of metal doping and non-metal loading on light energy driven degradation of organic dye using ZnO nanocatalysts

Photocatalytic degradation of azo dyes is seen as a viable technique for addressing environmental and energy concerns simultaneously. Therefore, the primary requirement is the creation of a better catalyst with adequate product selectivity for removal efficiency under solar light. Herein, pure ZnO and Cu (0.10 M) doped cotton stalk activated carbons with ZnO (Cu-doped ZnO/CSAC) were produced, and these are labelled as CZ1, CZ2, CZ3, and CZ3/CSAC, respectively. The optoelectronic and photodegradation efficiencies were examined regarding the impact of doping and loading samples. The XRD patterns confirmed that the CZ3/CSAC sample exhibited a hexagonal wurtzite structure. The XPS survey confirmed that Cu ions were incorporated into the ZnO lattice in a Cu2+ oxidation state. The band gap value (CZ3/CSAC) was reduced (2.38 eV) compared to pure ZnO and CZ3. Moreover, PL and EIS analysis proved more efficient at separating photoinduced charged carriers for CZ3/CSAC than all other samples. The CZ3/CSAC sample showed improved photocatalytic degradation efficiency (93.09%) compared to the pure ZnO and CZ3 samples using brilliant green (BG) dye under sunlight irradiation.

Photocatalytic degradation of azo dyes by ultra-small green synthesized silver nanoparticles

BackgroundThe presence of toxic dyes in wastewater is a serious problem for human health. In this work, the degradation of commercial azo dyes sold over-the counter in Mexico was studied, using as a photocatalyst ultra-small silver nanoparticles (AgNPs) green synthesized. MethodsFor the first time, the successful green synthesis of ultra-small AgNPs using, as both reducing-stabilizing agents (RSa), the aqueous extract of Pelargonium hortorum (Phf) flower or Allium fistulosum (Afs) stem, is reported. AgNPs were characterized by ultraviolet-visible (UV–Vis) and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopies, field emission scanning electron microscopy-energy dispersive spectroscopy (FE-SEM-EDS), and field emission transmission electron microscopy (FE-TEM). Significant findingsThe morphology of the AgNPs, in both cases, are spherical. AgNPs synthesized with Phf (AgNPs/Phf), which have a mode size of 2 nm (41.9%) and a bandgap of 2.38 eV, resulted in a photocatalytic degradation efficiency of 95%. On the other hand, AgNPs synthesized with Afs (AgNPs/Afs), which have a mode size of 0.6 nm (37.8%) and a bandgap of 2.43 eV, presented a photocatalytic efficiency of 100%. The photocatalytic efficiency and bandgap of the synthesized AgNPs were found to be inversely proportional to the AgNPs size; i.e. the smaller the AgNPs, the higher photocatalytic degradation, and bandgap exhibited.

Cost-effective microreactors for the synthesis of SnS nanoparticles and inline photocatalytic degradation of azo dyes

A simple wire-assisted cost-effective technique along with a laser assisted rapid microfabrication technique was used for the fabrication of microfluidic reactors to synthesize SnS nanoparticles and study their inline photocatalytic response. The SnS nanoparticles with an average size of 17 nm and optical band gap of 1.25 eV were synthesized using a PDMS based microreactor with a channel diameter of 450 µm. The less expensive PMMA based microreactor coated with SnS nanoparticles was employed in the photocatalytic degradation of EBT dye flowing at the rate of 50 µL/min providing ∼ 75 % instantaneous degradation at a catalyst loading of 30 mg.

Sol-Gel Synthesis of ZnO Nanoparticles Using Different Chitosan Sources: Effects on Antibacterial Activity and Photocatalytic Degradation of AZO Dye

Chitosan was used in the sol-gel synthesis of zinc oxide nanoparticles (ZnO NPs) as a capping agent in order to control the size, morphology, optical bandgap, photocatalytic efficiency, and antimicrobial activity. Different chitosan sources were used for the sol-gel synthesis of ZnO NPs, namely chitosan of shrimp shells, crab shells, and Streptomyces griseus bacteria. The photocatalytic efficiency was studied by using the methylene blue (MB) photodegradation test, and the antibacterial activity of the different types of ZnO NPs was investigated by the agar well diffusion technique. The particle size of ZnO NPs varied between 20 and 80 nm, and the band gap energy ranged between 2.7 and 3.2 eV. Due to the different chitosan sources, the ZnO NPs showed different antibacterial activity against Listeria innocua, Bacillus Subtiliis, Staphylococcus Aureus, Salmonella Typhimurium and Pseudomonas Aeruginosa. The ZnO NPs with lower band gap values showed better antibacterial results compared to ZnO NPs with higher band gap values. The MB dye removal of ZnO (shrimp shells), ZnO (crab shells), and ZnO (Streptomyces griseus) reached 60%, 56%, and 44%, respectively, at a contact time of 60 min, a low initial MB dye concentration of 6 × 10−5 M, a solution temperature of 25 °C, and a pH = 7.

Porous NH2-MIL-101(Fe) metal organic framework for effective photocatalytic degradation of azo dye in wastewater treatment

The porous iron-based metal organic frameworks (NH2-MIL-101(Fe)), which consists of 2-amino benzene dicarboxylic acid (H2BDC-NH2) and ferrous ions were synthesized through one-step hydrothermal method. The surface area and pore volume of as-synthesized NH2-MIL-101(Fe) were 66.48 m2/g and 0.09 cm3/g, respectively. The excellent photocatalytic performance endows NH2-MIL-101(Fe) to generate hydroxyl radical (OH), which then acting as efficiently active sites for azo dye degradation in wastewater. Meanwhile, the outstanding stability ability of NH2-MIL-101(Fe) indicates the potential candidate for wastewater treatment.

Hydrothermal Synthesis of GO/Pd/ZnO nanocomposite as Photocatalyst for Enhanced Photocatalytic Degradation of Azo Dye under Ultraviolet Light Irradiation

Hydrothermal Synthesis of GO/Pd/ZnO nanocomposite as Photocatalyst for Enhanced Photocatalytic Degradation of Azo Dye under Ultraviolet Light Irradiation

Surface conjugation of titanium dioxide nanoparticles on nano-graphene oxide enhances photocatalytic degradation of azo dyes under sunlight.

Here, conjugate of nano-graphene oxide (GO) and titanium dioxide nanoparticle (nTiO2) was proposed for the photocatalytic degradation of two toxic azo dyes, Congo red (CR) and Methylene blue (MB), under sunlight irradiation. Furthermore, the optimized weight ratio between GO and nTiO2 of 1:5 demonstrated the highest degradation efficiency. The nanoconjugate induced 85% degradation of 40ppm of CR in 60min and a complete degradation within 70min, while it degraded more than 90% of 20ppm of MB in 80min. The photocatalyst can be reused for five cycles of photocatalysis. Thus, the photocatalytic potential of GO/nTiO2 under visible light may be used as a very suitable and cost-effective photocatalyst industrially for the removal of toxic dyes from water.

Two multifunctional Cu(ii) coordination complexes with mixed ligands as efficient catalysts for the oxygen evolution reaction and photocatalytic degradation of methyl orange azo dyes

We constructed two novel multifunctional copper complexes as efficient catalysts for the OER and photocatalytic degradation of azo dyes.

Enhanced photocatalytic degradation of azo dye using rare-earth metal doped TiO2 under visible light irradiation

Lanthanum doped TiO2 nanoparticles (La doped TiO2) have been prepared by a sol-gel process using TiO(C4H9)4 as raw material and are characterized using XRD, FT-IR, SEM-EDS, TEM and UV-DRS. The insertion of La ion in TiO2 lattice has been confirmed by SEM-EDS and XRD data. TEM studies have confirmed that La ions are uniformly doped over TiO2 lattice. The band gap level of La doped TiO2 is decreased to 2.92 eV with a red shift due to charge transfer reaction which is confirmed by UV-DRS. The photocatalytic activities of the synthesized nanoparticles are evaluated for the degradation of Congo red dye (20 ppm) in an aqueous solution with La doped TiO2 (0.25 g) at pH= 6.3, under solar light irradiation. The photocatalytic results confirmed that the La doped TiO2 show good photocatalytic activity and can be considered as a promising photocatalyst for the degradation of organic pollutants in water. Due to the stability of La doped TiO2 nanoparticles, it could be reused for more than five cycles reaching 100% degradation efficiency.