Photocatalytic Degradation Of Methyl Violet Research Articles

H2O2-assisted photo-electrocatalytic and photocatalytic degradation of methyl violet by CuO-modified TiO2 nanotube arrays

Photoelectrocatalytic degradation is an environmental friendly and efficient technique providing solutions for the dire issue of water pollution. TiO2 nanotubes are widely used as the photocatalyst but its efficiency is restricted by the wide band gap. This study deals with the fabrication of CuO-modified TiO2 nanotubes by electrochemical anodization following the hydrothermal method to enhance the photocatalytic degradation. Optical studies revealed a reduction in the bandgap (2.12 eV) of CuO-modified TiO2 nanotubes, which plays an important role in increasing the photocatalytic activity. The effect of CuO loading on TiO2 nanotubes in photocatalytic degradation as well as the effect of bias and H2O2 on photo-electrocatalytic degradation were studied. In photocatalytic degradation, 0.05 M CuO–TiO2 photocatalyst produced a maximum degradation of 49.5 % in 8 h. Compared with the pristine TiO2 nanotubes, the photodegradation of CuO-loaded TiO2 nanotubes increased by 16 %. Furthermore, when an external bias was applied, the photodegradation efficiency increased by 36 %. In addition of H2O2 to the PEC system, 0.05 CuO–TiO2 photocatalyst produced 100 % degradation of methyl violet in 2.5 h. Reusability studies showed that the photocatalysts are stable and can therefore be used for practical applications such as photocatalytic degradation and photoelectrochemical degradation of methyl violet.

Photocatalytic degradation and kinetic investigations of ZnO-SnO2 heterostructures for treatment of methyl violet using non-conventional approach

Humans and wildlife alike are threatened by the ever-increasing levels of organic pollutants exist in the world's water bodies. Nanomaterials based on metal oxides have been considered strong alternatives for the elimination of organic pollutants. In the present study, ZnO-SnO2 nanocomposites were synthesized via non-conventional microwave and ultrasonic method using fruit extract of Carissa edulis as capping agent. The synthesized nanocomposites were studied using X-ray diffraction (XRD), Diffuse reflectance spectroscopy (UV–Vis-DRS), X-ray photoelectron spectroscopy (XPS), Fourier Infrared spectroscopy (FT-IR), Photoluminescence spectroscopy (PL), and Field emission scanning electron microscope (FE-SEM). Under UV light irradiation, photo-catalytic degradation of methyl violet (MV) was investigated by examining the influence of photocatalyst dosage, initial pollutant concentration, and pH of the reaction medium. The ideal conditions for MV degradation were at initial MV concentration of 10 mg/L, a 20 mg catalyst dose, and a pH of 7. The MV degradation of the synthesised ZnO-SnO2 nanocomposite was 91 % after 120 min. Scavenging experiments demonstrated that hydroxyl radicals (.OH) acts as a key role in the photo-degradation of MV. The reusability studies demonstrate that the synthesised ZnO-SnO2 has good stability for four cycles.

The Biogenic Synthesis of Bimetallic Ag/ZnO Nanoparticles: A Multifunctional Approach for Methyl Violet Photocatalytic Degradation and the Assessment of Antibacterial, Antioxidant, and Cytotoxicity Properties.

In this study, bimetallic nanoparticles (NPs) of silver (Ag) and zinc oxide (ZnO) were synthesized using Leptadenia pyrotechnica leaf extract for the first time. Monometallic NPs were also obtained for comparison. The characterization of the prepared NPs was carried out using various techniques, including UV-Visible spectroscopy (UV-Vis), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The latter confirmed the crystalline nature and diameter of the monometallic and bimetallic NPs of Ag and ZnO. The SEM images of the prepared NPs revealed their different shapes. The biological activities of the NPs were evaluated concerning their antibacterial, antioxidant, and cytotoxic properties. The antibacterial activities were measured using the time-killing method. The results demonstrated that both the monometallic and bimetallic NPs inhibited the growth of Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. The antioxidant activities of the NPs were evaluated using the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay and their cytotoxicity was checked using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The results indicated that the controlled quantity of the monometallic and bimetallic NPs did not affect the viability of the cells. However, the decreased cell (L-929) viability suggested that the NPs could have anticancer properties. Furthermore, the photocatalytic degradation of methyl violet and 4-nitrophenol was investigated using the prepared Ag/ZnO NPs, examining the factors affecting the degradation process and conducting a kinetic and thermodynamic study. The prepared Ag/ZnO NPs demonstrated good photocatalytic degradation (88.9%) of the methyl violet (rate constant of 0.0183 min-1) in comparison to 4-nitrophenol (NPh), with a degradation rate of 81.37% and 0.0172 min-1, respectively. Overall, the bimetallic NPs showed superior antibacterial, antioxidant, cytotoxic, and photocatalytic properties compared to the monometallic NPs of Ag and ZnO.

Fabrication of semiconducting photo nano catalyst ZnO/SnO2/ CdS to cleanup the dairy wastewater in sunlight

The creation of three nanoparticles and their use in the photocatalytic degradation of organic contaminants found in dairy effluent is reported here using a sustainable and repeatable process. Physicochemical techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and energy dispersive X-ray, were used to characterize the materials. The photocatalytic degradation of methyl violet using three nanoparticles is investigated using a UV–Vis spectrophotometer. Solar radiation and nanoparticles were investigated to improve photocatalysis procedures. The study aimed to determine the effects of concentrated sunlight and combined catalysts on chemical oxygen demand (COD), biochemical oxygen demand (BOD), and bacterial inactivation. The concentrated sun approach achieved 90% and 95% COD and BOD removal efficiency. Comparing all the metal oxide nanoparticles, the combined nanoparticles ZnO/CdS/SnO2 demonstrate significantly better performance in the photocatalytic process. The main objective is to treat dairy wastewater for reuse for various social purposes.

Green preparation of bract extract (Musa acuminate) doped magnesium oxide nanoparticles and their bioefficacy

Magnesium oxide nanoparticles (MgONPs) synthesized by efficient green approach have unique physiochemical properties. In this study, MgONPs are synthesized with bract extract of Musa acuminate, an agro waste. The surface plasmon resonance at 450 nm in UV spectrum and FTIR peaks at 601 and 890 cm−1 confirmed the presence of MgONPs. XRD pattern revealed high crystallinity of the nanoparticles with an intense orientation peak at 111, and the size was 13 nm. The particles were spherical with an average size of 24.85 nm. The elemental percentage of magnesium and oxygen were 68.55% and 31.45%. MgONPs had antibacterial activity against Bacillus subtilis, Escherichia coli, Vibrio harveyi, Vibrio parahemolyticus, and Staphylococcus aureus with MIC, 6 μg/mL. The IC50 value for MCF‐7 cell was 113.56 μg/mL, and the normal cell line was 785.69 μg/mL. The NPs also exhibited hemolytic features in a dose‐dependent manner. The MgONPs exhibited photocatalytic degradation of methyl violet, CBB G‐250, and malachite green in 60 min duration. MgONPs had promising antibacterial, cytotoxic, hemolytic, photocatalytic, and seed germination activity. They have the potential to serve as an additive in a variety of biological applications.

Preparation, Characterization and Photocatalytic Activity studies of Ag+, Cu2+ and Sn2+-doped Li2GeTeO6 under Visible Light Irradiation

Doping of cations into wide bandgap semiconductors is an effective method of increasing photocatalytic activity. This work aims to find out how dopant ions like Ag+, Cu2+ and Sn2+ affect the structural, optical and photocatalytic properties of Li2GeTeO6. The parent Li2GeTeO6 (LGTO) was synthesized by conventional solid-state method, whereas the Ag+, Cu2+ and Sn2+-doped Li2GeTeO6 were prepared by a simplistic ion-exchange method. Techniques such as XRD, FT-IR, SEM-EDS, N2 adsorption-desorption analysis, UV-Vis DRS, XPS, and PL were employed to examine the physico-chemical properties of the as-prepared materials and their photocatalytic activities on the degradation of methyl violet (MV) under visible light irradiation. The acquired photocatalytic activity results revealed that all doped samples displayed enhanced photocatalytic performance compared with parent LGTO. The Ag-LGTO had the best photocatalytic activity for MV degradation, with 68.6% degradation efficiency in 180 min of irradiation. Scavenging experiments were carried out to determine the role of various active species generated on the surface of Ag-LGTO during the photocatalytic degradation of MV. The reusability and stability of Ag-LGTO up to five cycles against MV degradation were also investigated. A photocatalytic mechanism for MV degradation over the Ag-LGTO sample was also proposed based on the findings described above.

Colloidal synthesis of AgGa(S1−xSex)2solid solution nanocrystals with composition-dependent crystal phase for efficient photocatalytic degradation of methyl violet

A series of AgGa(S1−xSex)2nanocrystals whose crystal phase features the dependence on their composition have been synthesized, and quasi-tetragonal AgGa(S0.7Se0.3)2presents the best photocatalytic efficiency of 88.48% for methyl violet.

Influencing Factors in the Synthesis of Photoactive Nanocomposites of ZnO/SiO2-Porous Heterostructures from Montmorillonite and the Study for Methyl Violet Photodegradation.

In this work, photoactive nanocomposites of ZnO/SiO2 porous heterostructures (PCHs) were prepared from montmorillonite clay. The effects of preparation methods and Zn content on the physicochemical features and photocatalytic properties were investigated. Briefly, a comparison of the use of hydrothermal and microwave-assisted methods was done. The Zn content was varied between 5 and 15 wt% and the characteristics of the nanomaterials were also examined. The physical and chemical properties of the materials were characterized using X-ray diffraction, diffuse-reflectance UV-Vis, X-ray photoelectron spectroscopy, and gas sorption analyses. The morphology of the synthesized materials was characterized through scanning electron microscopy and transmission electron microscopy. The photocatalytic performance of the prepared materials was quantified through the photocatalytic degradation of methyl violet (MV) under irradiation with UV and visible light. It was found that PCHs exhibit greatly improved physicochemical characteristics as photocatalysts, resulting in boosting photocatalytic activity for the degradation of MV. It was found that varied synthesis methods and Zn content strongly affected the specific surface area, pore distribution, and band gap energy of PCHs. In addition, the band gap energy was found to govern the photoactivity. Additionally, the surface parameters of the PCHs were found to contribute to the degradation mechanism. It was found that the prepared PCHs demonstrated excellent photocatalytic activity and reusability, as seen in the high degradation efficiency attained at high concentrations. No significant changes in activity were seen until five cycles of photodegradation were done.

Preparation, characterization and properties of the ternary composite β2-SiW11/polyaniline/graphene oxide

The composites β2-SiW11/GO and β2-SiW11/PANI/GO were prepared by using graphene oxide as a carrier. Properties of the composites were characterized by UV-visible spectroscopy (UV-vis), infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM-EDS), transmission electron microscopy (TEM), N2 adsorption desorption and thermal gravimetric analysis. Properties of the composites were investigated by using methyl violet simulated industrial wastewater. The results showed that this composite had photocatalytic activities for many dyes, and the activity was higher than that of Degussa P25(TiO2). The photocatalytic performance of β2-SiW11/PANI/GO had a higher activity than that of PANI, β2-SiW11 and β2-SiW11/GO, with photodegradation reaching 95.98% under 30 W ultraviolet light for 150 min. The reaction kinetics for photocatalytic degradation of methyl violet followed a first-order process. The prepared composite was recyclable and the performance remained good. The possible mechanism of photocatalytic activity of dopant material is discussed and schematized.

Efficient photocatalytic degradation of methyl violet using two new 3D MOFs directed by different carboxylate spacers

Both the MOFs proved to be good candidates for the photocatalytic degradation of methyl violet. The mechanism of these photocatalytic degradations is discussed.

A Sharp Jump in Photocatalytic Activity of Elemental Sulfur for Dye Degradation in Alkaline Solution.

Elemental sulfur is a low-cost and abundant substance as one of the largest by-products of the oil industry which was widely used in many industrial activities. Cyclo-octasulfur (S8 ) is one of the sulfur allotropes that is a very stable substance in standard conditions. In this study, we report a low-cost and fast method for the degradation of methyl violet in water under visible light and also sunlight by using elemental sulfur (S8 ). The results show that sulfur is a good photocatalyst which operates under visible light and can be utilized for degradation of methyl violet. The photocatalytic degradation of methyl violet in acidic, neutral, and alkaline media was investigated, and it was found that the photocatalytic efficiency increases dramatically in alkaline solution. The effects of the initial concentration of the dye, photocatalyst dosage, solution pH, and photocatalyst reusability were investigated. The kinetics of the reaction were studied in detail, and the photocatalytic rate equation was presented.

Enhancement of photocatalytic activity of ZrO2 nanoparticles by doping with Mg for UV light photocatalytic degradation of methyl violet and methyl blue dyes

In this study, pristine ZrO2 (600 °C) and Mg (0.02, 0.04, 0.06, 0.08 M)-doped ZrO2 nanoparticles were effectively synthesized at about 10 nm size and achieved complete degradation of methyl violet and methyl blue dyes under UV irradiation. The calcined products were analyzed by XRD, FTIR, UV-DRS, PL, FESEM-EDX, TEM-SAED pattern and XPS techniques. The tetragonal crystal structure of the pristine ZrO2 and Mg (0.02–0.08 M)-doped ZrO2 nanoparticles were affirmed by XRD analysis. The Mg (0.08 M)-doped ZrO2 nanoparticles were approximately in quasi-spherical morphology and high agglomeration was confirmed by FESEM and TEM results. The surface defects and oxygen vacancies were analyzed by PL spectroscopy. The Mg (0.08 M)-doped ZrO2 nanoparticles exhibited enlarged photocatalytic activity with 94% and 90% degradation of methyl violet and methyl blue dyes under UV irradiation.

Effects of chlorinated Pd precursors and preparation methods on properties and activity of Pd/TiO2 catalysts.

We investigated the effects of Pd precursors and preparation methods on the physicochemical properties and performance of Pd/TiO2 catalysts in the photocatalytic degradation of methyl violet. To confirm the influence of the precursors, Pd/TiO2 catalysts were prepared via chemical reduction (CR) using four different Pd precursors. Additionally, to determine the effects of preparation methods, Pd/TiO2 catalysts were fabricated using K2PdCl4 precursor via three different methods: CR, deposition–precipitation (DP), and impregnation. The CO chemisorption results showed that the catalyst prepared via DP using the K2PdCl4 precursor, i.e., Pd/TiO2_K_DP, displayed the highest Pd dispersion of 12.42% owing to the stable formation of Pd(OH)2, which strongly interacted with the –OH groups on the TiO2 support. Although the catalyst prepared via CR using the Pd(NH3)4Cl2·H2O (PA) precursor, i.e., Pd/TiO2_PA_CR, had the lowest Pd dispersion of 0.7%, it exhibited the highest absorption of 26% after 30 min in the dark. It was found that high Pd2+/Pd0 ratio in dark conditions adversely affected the absorption of MV owing to electrostatic repulsion between the cationic dyes and metal nanoparticles. However, the Pd dispersion and the specific surface area played a key role in the photocatalytic activity under UV irradiation. Pd/TiO2_K_CR with higher Pd dispersion showed the highest photocatalytic activity and reaction rate of 0.0212 min−1.

Functionalization of hydroxyapatite derived from cockle (Anadara granosa) shells into hydroxyapatite\u2013nano TiO2 for photocatalytic degradation of methyl violet

Photocatalyst of hydroxyapatite–nano TiO2 (HAp-nTiO2) was prepared from phosphatation of calcined cockle (Anadara granosa) shells followed by dispersion of nano TiO2 powder into HAp precipitate and calcination at 400 °C for 2 h. The prepared material was characterized using X-ray diffraction, scanning electron microscope–energy dispersive X-ray spectrophotometry, gas sorption analysis, and UV-Vis diffuse reflectance spectrophotometry. The photocatalytic activity of the material was evaluated for methyl violet degradation over photocatalysis and photooxidation mechanism. The results showed that the homogeneous dispersion of TiO2 in the HAp-nTiO2 composite was achieved, as seen in the X-ray diffraction analysis, diffuse reflectance UV-Vis, and gas sorption analyses. The physicochemical and photocatalytic character of the composite exhibited the positive role of HAp as TiO2 support in enhancing the photocatalytic activity with a higher turnover number and reusability property than that of pure TiO2. It was also noted that the HAp-nTiO2 composite demonstrated rapid methyl violet degradation over photooxidation rather than by photocatalytic mechanism.

Hydrothermal synthesis of SnO2 nanoparticles and its photocatalytic degradation of methyl violet and electrochemical performance

Quality SnO2 nanoparticles were synthesized through hydrothermal process using Tin(IV) chloride pentahydrate (SnCl4.5H2O) and Sodium hydroxide (NaOH). The synthesized nanoparticles were characterized by x-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), high resolution scanning electron microscopy (HRSEM), energy dispersive x-ray spectrometry (EDX), high resolution transmission electron microscopy (HRTEM), Ultra violet-visible diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL). The band gap energy (Eg) of the synthesized SnO2 nanoparticles were significantly blue shifted. An enhanced PL emission of SnO2 nanoparticles at 300 nm excitation exhibited emission at 327, 386, 451, 467 and 500 nm, respectively. Furthermore, photocatalytic activity of synthesized SnO2 nanoparticles were studied by degrading methyl violet dye under sunlight irradiation for a time of 120 min. Additionally, electrochemical performance of the SnO2 nanoparticles were investigated, which gave a capacitance value of 87 F g−1. The SnO2 nanoparticles had potential application as photocatalyst and electrochemical performances.

Rapid degradative effect of microbially synthesized silver nanoparticles on textile dye in presence of sunlight

Abstract In the study, the dye collected from industry was identified as methyl violet by LC-MS/MS analysis. The biosynthesized silver nanoparticles (AgNPs) used were characterized by UV–visible spectrophotometry, HR-TEM and FT-IR analysis. Further, the AgNPs were used to evaluate the photocatalytic degradation of methyl violet. The results showed rapid degradation (85.56%) of methyl violet within a period of 20 min in presence of AgNPs and sunlight. The superior photocatalytic activity of AgNPs observed in the study indicates its application for dye degradation.

Physical and photo-electrochemical characterization of natural phosphate material. Application to basic dyes photodegradation

Photocatalytic degradation of methyl violet (MV) and rhodamine B (RhB), in single and binary systems, using natural phosphate rock was investigated, motivated by its low cost, abundance, and environmental friendliness. The physical and photo-electrochemical properties of the material were studied. The diffuse reflectance spectrum indicated a direct allowed optical transition at 2.66 eV. The thermal variation of the electrical conductivity showed semiconductor behavior following an exponential type law with low activation energy. Photo-electrochemical studies revealed that the phosphate material exhibited n-type behavior with conduction band of 0.16 VRHE and valence band of 2.82 VRHE, permitting production of both $${\text{O}}_{2}^{ \cdot - }$$ and HO· oxidizing radicals, respectively, responsible of photodegradation of MV and RhB. In single solutions, both dyes were degraded under ultraviolet (UV) light, within 240 min for MV and 330 min for RhB. However, in binary systems, degradation of RhB was effective only when most of the MV had disappeared. Photocatalytic degradation of MV and RhB on natural phosphate.

Efficient photocatalytic degradation of methyl violet with two metall–organic frameworks

Two metal–organic frameworks, [Co2(L)(H2O)2(4,4′-bipy)]·3CH3CN (1) and [Mn2(L)(1,10-phen)(H2O)]·H2O (2) (H4L = 5-[bis(4-carboxybenzyl)-amino]isophthalic acid; 4,4′-bipy = 4,4′-bipyridine, 1,10-phen = 1,10-phenanthroline), with two different N-donor ligands have been synthesized. The structures of both MOFs were determined using single-crystal X-ray diffraction technique. MOF 1 shows 3D uncommon (4,6,6)-c net with (4.53.62)2(57.66.82)(42.54.66.72.8) topology while in the case of 2, only L4− ligands link Mn(II) ions into a 2D layer structure with chelating 1,10-phen ligand. The results demonstrate that variation in the N-donor ligands plays a pivotal role in deciding the framework of the two MOFs. Both MOFs have been exploited as photocatalyst materials for the degradation of MV. The photocatalysis results indicate that the two MOFs are stable and are prospective candidates for degradation of methyl violet under UV light irradiation. Additionally, 2 displayed superior photocatalytic activity in comparison to 1. The probable photocatalytic activity mechanism for both 1 and 2 against MV has been proposed using density of states (DOS) calculations.

Luminescent sensing of Cu2+, CrO42− and photocatalytic degradation of methyl violet by Zn(II) metal-organic framework (MOF) having 5,5′-(1H-2,3,5-triazole-1,4-diyl)diisophthalic acid ligand

A porous Zn(II) metal–organic framework (MOF) [Zn(H2L)(4,4′-bipy)0.5]n (1) has been selected and its luminescence sensing for cations and anions as well as the photocatalytic property against methyl violet have been explored. Luminescence studies indicated that 1 could be an efficient multifunctional fluorescent material for highly sensitive detection of metal cation Cu2+ and anions CrO42−. The luminescence intensity of 1 was found to decrease proportionately with increase in the concentration of Cu2+ and CrO42−. Furthermore, the photocatalytic property of 1 for degradation of the methyl violet (MV) have been explored and a possible photocatalytic mechanism have been proposed using density of states (DOS) and partial DOS (pDOS) calculations.

Fluorine-doped nanocrystalline ZnO powders prepared via microwave irradiation route as effective materials for photocatalyst

In this report, we have successfully synthesized nanocrystalline pure and F doped ZnO prepared by one-step microwave irradiation method without using any post annealing treatment. The effect of F dopant on structural, morphological and optical properties were systematically investigated by using powder X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), Raman spectra, UV–Vis absorption spectra and photoluminescence spectra analysis. XRD results reveals that both pristine and F doped ZnO had a hexagonal wurtzite type structure and the results are in good agreement with standard JCPDS data (card no. 36-1451). FESEM images showed that random platelets morphology with average diameter around 50–35 nm. A considerable red-shift in the absorption edge and decreasing the band gap of pure ZnO (3.32–3.12 eV) was confirmed though UV–Vis spectra. The defect in crystal and oxygen vacancy was analyzed through PL spectra analysis. The photocatalytic activities of the catalyst powders were evaluated by photocatalytic degradation of methyl violet (MV) and rhodamine B (RhB) and the results showed that the doping of F into ZnO nanoparticles could enhance photocatalytic activity compared to the undoped ZnO nanoparticles, this could be due to reduction of band gap and superior textural properties. The improved photocatalytic mechanism by F doping was also discussed in detail.