Degradation Of Indigo Carmine Research Articles

Preparation of mesoporous ThO2 nanoparticles: Influence of calcination on morphology and visible-light-driven photocatalytic degradation of indigo carmine and methylene blue

The present article reports the synthesis of thoria nanoparticles (ThO2 NPs) via sol-gel process and examines the effect of calcination temperature of ThO2 on the morphology and photocatalytic degradation of indigo carmine (IC) and methylene blue (MB) under visible-light. As-synthesized white crystals of ThO2 were subjected to calcination at different temperatures, viz. 700 °C (TH-700), 800 °C (TH-800), and 900 °C (TH-900). The effect of calcination temperature on the structural, morphological, thermal, surface area-porosity, and optical properties of ThO2 NPs were investigated by diverse analytical techniques. XRD patterns show the cubic-space group Fm-3m (225) with parameter a = 5.597 Å and reveals crystallite sizes increased with calcination temperature. The bandgap energy was found to be 1.85 eV, 2.33 eV, and 2.71 eV for TH-700, TH-800, and TH-900 NPs, respectively, calculated by Kubelka-Munk (KM) plot. SEM and TEM unveil that the sample TH-700 calcined at a low temperature of 700 °C yields assembled nanosheets, while at higher temperatures, i.e., 800 °C (TH-800) and 900 °C (TH-900), produces agglomerated nanomaterials. Further, TH-700 sample exhibits enhanced photocatalytic degradation within 120 min for both IC and MB dye than TH-800 and TH-900 counterparts. Among the dyes, IC shows improved photocatalytic efficiency than MB for TH-700, owing to the increased optical absorption and improved separation of photogenerated charge carriers. The reusability study of TH-700 reveals that the catalysts were stable up to four successive cycles with no drastic changes in photocatalytic efficiency. Also, systematic photodisintegration of IC was investigated by Liquid chromatography–mass spectrometry (LC–MS).

3D ZnO sunstar rose nanoflowers morphology with surfactant-assisted reflux exhibit excellent optical properties and photocatalytic activity against hazardous organic dyes

Sunstar rose ZnO nanoflowers morphology was synthesized using the surfactant-assisted reflux technique. The synthesized 3D ZnO nanoflowers were subjected to various characterization techniques (X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–Vis diffuse reflectance spectroscopy (UV-DRS), Photoluminescence (PL) spectroscopy, Raman spectra, thermogravimetry analysis (TGA), differential thermal analysis (DTA), X-ray photoelectron spectrometer (XPS), N2 adsorption-desorption isotherms (BET), field emission scanning electron microscopy (FESEM), energy dispersive X-rays analysis (EDAX) and high resolution transmission electron microscopy (HRTEM)). The sunstar rose morphology was achieved under reflux conditions; the heating throughout the material uniformly allowed the nanoflowers to grow along the c-axis due to the temperature, and surfactant also plays a significant role in the shape of the flowers, as confirmed by FESEM and HRTEM analysis. Further, the synthesized 3D ZnO nanoflowers were utilized the photocatalytic activity was investigated for the degradation of hazardous organic dyes like cationic (Methylene blue (MB)) and anionic (Indigo Carmine (IC)) under sunlight. Overall, it was observed that the degradation of MB and IC was found to be 99.5 (50 min) and 98% (60 min), respectively. ZnO nanoflowers are an efficient photocatalyst for MB compared to IC, as MB degrades faster than IC, which takes less time for degradation.Moreover, shown through photocatalytic processes that synthesized ZnO nanoflowers were highly recyclable, suggesting their potential application in environmental remediation. After the fourth cycle, the effective degradation of MB and IC was 78 and 70%, respectively. The radical quenching test shows that ZnO exhibits charge migration, which may account for its high photoactivity.

Ferromagnetic Biochar Prepared from Hydrothermally Modified Calcined Mango Seeds for Fenton-like Degradation of Indigo Carmine

Biochar and ferromagnetic biochar obtained from the pyrolysis of dried mango seeds and modified using a hydrothermal method were used as catalyst for the heterogeneous degradation of indigo carmine in an aqueous medium. These prepared biochars were characterized using different techniques: Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The analyses of the results revealed the presence of iron oxide in the form of magnetite (Fe3O4) in the catalyst. The catalytic tests carried out with this composite material showed a significant degradation of indigo carmine. The maximum degradation of indigo carmine in the aqueous solution was reached after 240 min of agitation. The Fenton degradation process using irradiation with a 100 W electric lamp and hydrogen peroxide (concentration 4 mol/L) showed the best results at pH = 3. From this study, it emerged that the second-order kinetic model better described the degradation process, and it gave lower half-lives compared to those obtained with the first-order kinetic law. The study also showed that ferromagnetic biochar could be prepared from mango seeds and used for the degradation of indigo carmine in an aqueous solution.

The Biodegradation of Indigo Carmine by Bacillus safensis HL3 Spore and Toxicity Analysis of the Degradation Products

The aims of this article were to investigate Bacillus safensis HL3 spore for its capacity to degrade and detoxify indigo carmine and to provide an effective biological agent for the treatment of isatin dye wastewater. Bacillus safensis HL3 spore was found to decolorize indigo carmine by 97% in the presence of acetosyringone within 2 h. Significantly increased activities of spore laccase, intracellular tyrosinase, and lignin peroxidase upon exposure to indigo carmine were observed. The results of RT-qPCR also showed that the expression of laccase gene was significantly increased. The spore has the ability to degrade indigo carmine through oxidization. Furthermore, the pathway by which indigo carmine is degraded was investigated using liquid chromatography-mass spectrometry analysis to identify the biodegradation products. A detailed pathway of indigo carmine degradation by bacterial spores was proposed for the first time. Toxicity tests indicated that the biodegradation products of indigo carmine are non-toxic to Nicotiana tabacum seeds and are less hazardous to human erythrocytes than the original dye. Indigo carmine is a typical recalcitrant dye and severely jeopardizes human health. The results demonstrate the utility of the spore from Bacillus safensis HL3 for the degradation of indigo carmine and simultaneous reduction of its toxicity.

Electrochemical degradation of indigo carmine, P-nitrosodimethylaniline and clothianidin on a fabricated Ti/SnO2–Sb/Co-βPbO2 electrode: Roles of radicals, water matrices effects and performance

In this study, the kinetic degradation of several typical organic pollutants was performed on a synthetic electrode (Ti/SnO2–Sb/Co-βPbO2). The surface structure and the electrochemical properties of the prepared electrode were investigated, confirming the successful preparation of the electrode using an electrochemical deposition method. The outer layer (Co-βPbO2) played an important role in reducing the resistance of the electrode and improving its degradation efficiency. The results showed that indigo carmine (IC), p-nitrosodimethylaniline (RNO), and clothianidin (CLO) were effectively degraded within 20 min of electrolysis. Their degradation in the electrochemical process followed the first-order kinetic model with the degradation rate constant of IC being higher than that of RNO and CLO. This was proved by the difference in the reactivity of the target pollutants toward oxidizing radicals (i.e., •OH, SO4•-, and Cl•). Their second-order rate constant towards radicals were in the range of 109 - 1010 M−1 s−1 with the highest value being that for IC: k·OH,IC = 15.1 × 109 M−1 s−1 and kSO4•−,IC = 7.4 × 109 M−1 s−1. The study calculated the contribution of some oxidizing species, including direct electron transfer (DET), •OH, SO4•-, and other reactive oxygen species (ROS). Solution pH, supporting electrolyte, and water matrix affected the degradation efficiency of pollutants and the contribution of the oxidizing species. Br− and I− ions enhanced the degradation rate of organic pollutants, while Fe2+, HCO3−, and humic acid (HA) reduced it. In addition, the toxicity, total organic carbon (TOC) removal, mineralization current efficiency (MCE), energy consumption, recyclability and stability of the prepared electrode were studied, suggesting that the prepared Ti/SnO2–Sb/Co-βPbO2 is a good candidate for treating organic pollutants using the electrochemical oxidation process.

Green SBA-15 as a Fenton Catalytic Support for Efficient Degradation of Indigo Carmine

Green mesoporous SBA-15 was synthesized by using corn stack ash (CSA), a new renewable silica source, as the main raw material. 80 wt% sodium silicate solution from CSA was mixed with a tetraethyl orthosilicate (TEOS) solution, and fi nally after a hydrothermal process, mesoporous SBA- 15 was obtained. Subsequently, iron metal was incorporated into the prepared SBA-15 and used as an effi cient Fenton catalyst for degradation of indigo carmine (IC) under various conditions. Effects of various parameters of the Fenton process: initial pH, H2O2 concentration, Fe content, and reaction temperature were studied. It was observed that Fe2O3/80CSBA demonstrated good activity not only for a wide range of pH (both of acidic and basic conditions), but also at room temperature. Using the optimum condition, 98% of IC removal can be reached within 10 min. Moreover, the catalyst exhibited long-term stability and strong resistance to leaching of Fe species, while incorporating metal only 0.5 wt% of metal.

Preparation and Property Characterization of In2YSbO7/BiSnSbO6 Heterojunction Photocatalyst toward Photocatalytic Degradation of Indigo Carmine within Dye Wastewater under Visible-Light Irradiation.

In2YSbO7 and In2YSbO7/BiSnSbO6 heterojunction photocatalyst were prepared by a solvothermal method for the first time. The structural characteristics of In2YSbO7 had been represented. The outcomes showed that In2YSbO7 crystallized well and possessed pyrochlore constitution, a stable cubic crystal system and space group Fd3m. The lattice parameter of In2YSbO7 was discovered to be a = 11.102698 Å and the band gap energy of In2YSbO7 was discovered to be 2.68 eV, separately. After visible-light irradiation of 120 minutes (VLGI-120M), the removal rate (ROR) of indigo carmine (IC) reached 99.42% with In2YSbO7/BiSnSbO6 heterojunction (IBH) as a photocatalyst. The ROR of total organic carbon (TOC) reached 93.10% with IBH as a photocatalyst after VLGI-120M. Additionally, the dynamics constant k which was taken from the dynamic curve toward (DCT) IC density and VLGI time with IBH as a catalyst reached 0.02950 min−1. The dynamics constant k which came from the DCT TOC density and VLGI time with IBH as a photocatalyst reached 0.01783 min−1. The photocatalytic degradation of IC in dye wastewater (DW) with IBH as a photocatalyst under VLGI was in accordance with the first-order kinetic curves. IBH was used to degrade IC in DW for three cycles of experiments under VLGI, and the ROR of IC reached 98.74%, 96.89% and 94.88%, respectively, after VLGI-120M, indicating that IBH had high stability. Compared with superoxide anions or holes, hydroxyl radicals possessed the largest oxidative ability for removing IC in DW, as demonstrated by experiments with the addition of trapping agents. Lastly, the probable degradation mechanism and degradation pathway of IC were revealed in detail. The results showed that a visible-light-responsive heterojunction photocatalyst which possessed high catalytic activity and a photocatalytic reaction system which could effectively remove IC in DW were obtained. This work provided a fresh scientific research idea for improving the performance of a single catalyst.

An efficient removal of Indigo Carmine dye (IC) from aqueous medium using environmental friendly synthesized ZnAl2O4

In recent years, materials have not only shown significant application in human life but also have a very important role in various industries. Over the last few decades, metal oxide and mixed metal oxide (MMO) have been acknowledged as efficient and environment-friendly alternatives to present-day available materials for different chemical, food, dye, and pharmaceutical industries along with environmental treatments. In view of the significant use of MMO in different fields, in the current work, nanocrystalline zinc aluminate (ZnAl2O4) has been successfully synthesized by the eco-friendly, cost-effective solid-state Mechanochemical (MCh) method, and it is used for the photocatalytic degradation of Indigo Carmine (IC) pollutant present in the wastewater of different industries. Numerous appropriate techniques, like Fourier-transform infrared spectroscopy (FT-IR), Ultraviolet–Visible Diffuse Reflectance Spectroscopy (UV-DRS), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM), were used for its characterization. It is revealed that ZnAl2O4 exhibits a pronounced photocatalytic activity under the influence of UV–visible light exposure. The present study also reveals a possible pathway for photocatalytic degradation of IC using liquid chromatography-mass spectrometry (LC-MS).

Visible light assisted surface plasmon resonance triggered Ag/ZnO nanocomposites: synthesis and performance towards degradation of indigo carmine dye.

Water pollution caused by organic compounds, generated from different industries, has gained attention worldwide today. In this regard, significant efforts have been made for a suitable dye degradation technology. Zinc oxide (ZnO)-based photocatalysts are considered novel materials to degrade organic effluents in contaminated water. The facile synthesis of Ag/ZnO nanocomposites and its application for the enhanced degradation of indigo carmine (IC) dye under visible light irradiation is reported in this paper. The prepared photocatalysts were characterized using various analytical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron (XPS) spectroscopy, FTIR, Raman, impedance study, UV-Vis, and photoluminescence (PL). Prepared Ag/ZnO nanocomposites were tested for degradation of IC dye in visible light. The degradation efficiency of IC dye was found to be 95.71% in 120min, with a rate constant of 0.02021min-1. This improved photocatalytic activity of Ag/ZnO nanocomposites was mainly due to the absorption of visible light caused by surface plasmon resonance (SPR) derived from Ag nanoparticles (NPs) and electron-hole separation. Radical trapping experiments suggest that holes (h+) and superoxide radical (O2•-) are the key factors in photocatalytic IC dye degradation.

TRATAMIENTO DE AGUA CON UNA DESCARGA CORONA PULSADA

One of the fastest growing technological applications in recent years in the area of non-thermal plasmas is the treatment of water with discharges in (and in contact with) liquids. Reactive chemical species are generated in the plasma in the gas phase and enter the liquid by diffusion or are generated at the gas-liquid interface, thus changing its physicochemical properties, without the addition of external chemical compounds. Depending on the form of application of the plasma, well-differentiated effects can be achieved: on the one hand, the purification of water through the degradation of organic pollutants, and on the other, its activation, through long-lived reactive species, for later use in seeds and food treatments. In this work, the first results obtained in the water treated with a pulsed corona discharge under different exposure times are reported. In particular, measurement results of indigo carmine degradation; electric conductivity; pH; aqueous concentrations of reactive species, such as nitrate, nitrite, hydrogen peroxide and ozone, are reported. The results are discussed and compared with published data.

Facile synthesis of amorphous zirconium phosphate graphitic carbon nitride composite and its high performance for photocatalytic degradation of indigo carmine dye in water

In this work, we reported the synthesis of amorphous zirconium phosphate graphitic carbon nitride (a-ZrP/g-C3N4) composite via the formation of amorphous zirconium phosphate (a-ZrP) onto the surface of graphitic carbon nitride (g-C3N4) nanosheets. The prepared a-ZrP-g-C3N4 composite was characterized by different analytical techniques. The FTIR, XRD, TEM, SEM, XPS, and PET surface area confirmed the successful preparation of a-ZrP-g-C3N4 nanocomposite with a high surface area (60 m2/g) and pore width less than 2 nm. The a-ZrP-g-C3N4 nanocomposite showed superior photocatalytic efficiency for the degradation of indigo carmine (IC) dye compared to the (g-C3N4) nanosheets. At room temperature and normal pH, 5 mg of the photocatalyst can degrade about 100% of 50 mL of an aqueous solution containing 10 ppm IC dye within 30 min under UV light irradiation (4 W at 356 nm). The photodegradation kinetics fitted well with the first-order kinetic module. The high photodegradation efficiency was attributed to the unique structure of the prepared nanocomposite since a-ZrP crosslinks g-C3N4 nanosheets in mesoporous structure which generate multichannel photocatalytic sites in addition to the inhibition of photogenerated electrons (e–) and holes (h+) recombination. The results of reusability revealed that the nanocomposite can be used several times without a significant change in its photocatalytic activity. Owing to the ease of synthetic strategy, cost-effective starting materials, and high photodegradation efficiency, a-ZrP/g-C3N4 composite has the potential to be a promising photocatalyst to remediate water-containing indigo carmine dye.

Brazilein modified zinc oxide nanorods with enhanced visible light-responsive photocatalytic efficiency

Photocatalytic efficiency of ZnO nanorods has been investigated with respect to the concentration of brazilein. Brazilein modified ZnO nanorods were prepared by an impregnation process with 1.0%w/v, 2.5%w/v, and 5.0%w/v of brazilein solution. In order to correlate the variation in concentration distributions and photocatalytic performance, the phase composition, optical properties, and photo-catalytic activities of brazilein modified ZnO nanorods prepared with different brazilein concentrations have been investigated and compared to an unmodified ZnO nanorods. The photocatalytic properties were measured in terms of indigo carmine degradation under visible light irradiation. It was found that ZnO nanorods with the highest visible light-responsive photocatalytic efficiency were achieved by the modification of 5.0%w/v of brazilein resulting in indigo carmine degraded faster than the case of unmodified ZnO nanorod about 60% within 5 h.

Hydrazine modified g-C3N4 with enhanced photocatalytic activity for degradation of indigo carmine

Polymeric graphitic carbon nitride (g-C3N4) was obtained from urea and modified by heat polymerization at 550 °C in the presence of hydrazine as a modifier agent. The influence of in-situ generated NH3 by hydrazine decomposition at different contents (0.5, 1, 1.5, and 2 mL) on the physicochemical properties and surface properties (water contact angle and point of zero charge) of the g-C3N4 were investigated. The modified g-C3N4 were analyzed by X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, photoluminescence, Fourier Transform Infrared, water contact angle, surface area, and the point of zero charge. The in-situ generated NH3 induced an evolution from nano-flakes to lamellar plate morphology depending on stacked interplanar. The influence of surface properties on the photocatalytic response of the unmodified and modified g-C3N4 was tested in the photodegradation of indigo carmine dye at pH = 3.5 and 6.5 solutions under blue LEDs light. The photostability of the samples was tested after 4 cycles of reaction. The properties (surface area (SA); water contact angle (WCA), and optical gap) influence the photocatalytic response, which was summarized in a single parameter defined as SA/(WCA*gap). The maximum value of this product match with results obtained for the most active photocatalyst (U-Hz1).

Indigo Carmine Degradation in Water Induced by a Pulsed Positive Corona Discharge in Air: Discharge and Postdischarge Effects

In recent years, one of the fastest growing technological applications in the field of nonthermal plasmas is the degradation of organic contaminants of water. In this work, the degradation of indigo carmine (IC) in water induced by a pulsed positive corona discharge operating in ambient air is reported. Degradation levels in different volumes of IC in solution with distilled water treated with different plasma exposure times immediately after discharge (0 h), and in the postdischarge up to 24 h were examined. To explain the IC discoloration in the postdischarge phase, a chemical model was developed. The stability of the reactive species in solution nitrate (NO3−), nitrite (NO2−) and hydrogen peroxide (H2O2), as well as the properties of the solution (electrical conductivity, pH) were also measured. The results suggest that the hydroxyl radical (OH˙) as well as ozone (O3) are the main oxidizing species during the discharge phase, being primarily formed in the gas phase through plasma-mediated reactions and then transferred to the liquid by diffusion, while the OH˙ production in the bulk liquid through the decomposition of peroxinitrous acid (O=NOOH) plays a major role in the IC degradation during the postdischarge. These results are associated with a noticeably increase in the energy-yield values observed at 24 h post-treatment.

Proposed pathway of degradation of indigo carmine and its co-metabolism by white-rot fungus Cyathus bulleri

The stimulation of growth by the addition of indigo carmine (5, 5 indigo disulfonic acid sodium salt, IC) was studied in the white-rot fungus Cyathus bulleri. C. bulleri was grown on a variety of solid medium and addition of IC (5000 mg/L) resulted in enhancement of growth, particularly on malt-extract agar. Stimulation of growth by IC was also observed in liquid cultures grown in potato dextrose broth. IC was degraded into anthranilic acid by oxidoreductases, particularly laccases, present in the culture broth of the fungus grown on wheat bran and orange peelings, which was confirmed by treatment of IC with purified laccase. Anthranilic acid was proposed to further enter into the tryptophan (TRP) biosynthetic pathway, as demonstrated by up-regulation of newly identified trpD, trpC and trp1 genes from this fungus. These genes encode anthranilate phosphoribosyl transferase, a multi-functional enzyme with phosphoribosyl anthranilate isomerase/other activities and tryptophan synthase respectively. No such increased transcription of these genes was observed in the absence of IC.

Laccase immobilized on chitosan-polyacrylic acid microspheres as highly efficient biocatalyst for naphthol green B and indigo carmine degradation

Low cost and non-toxic microspheres constituted by different ratios of chitosan (Cs) and polyacrylic acid (PAA) were manufactured as carriers for laccase (Lc). The CsPAA microspheres characterization proved that the PAA content played an important role on the size, surface morphology and rheological properties, and modulated the enzyme immobilization. The immobilization of Lc involved a multi-step procedure in which the 1-ethyl-3-(3-dimethylaminopropyl carbodiimide hydrochloride (EDC) was used as “zero length” crosslinker. The product with the largest active enzyme amount (44.38 mg Lc/g dry support), and the best operational stability profile was 10CsPAALc3. Also, this product contained the lowest PAA concentration and had excellent rheological properties. Moreover, two current hazardous chemicals, indigo carmine (IC) and naphthol green B (NG), were used as model dyes in practical applications. The biocatalytic decomposition of NG and IC was 1.67 and 2.4 times faster for 10CsPAALc3 compared to the free enzyme. The kinetic profile revealed that the immobilized Lc was less prone to substrate, operational and thermal inactivation. For example, the thermal inactivation for 10CsPAALc3 decreased by approximately 25% when dyes were used as substrate and by 11.71% for ABTS, as compared with the free Lc. The recycling test showed that in 5 cycles the immobilized Lc preserves 81% with NG and respectively 72% for IC of initial activity. The results prove that the new immobilized product can be successfully used in indigoid and metal-complex dyes biodegradation.

Coconut Fiber Decorated with Bismuth Vanadate for Enhanced Photocatalytic Activity.

Bismuth vanadate/coconut fiber (BiVO4/CF) composites were synthesized by coprecipitation and calcination methods. All catalysts used in this work were prepared by a simple coprecipitation method and fully characterized by means of XRD, SEM-EDS, PL, BET N2 adsorption, zeta potential, and UV–vis DRS. Degradation of indigo carmine (IC) under visible light irradiation was tracked by the UV–vis technique. It was documented that XRD patterns of BiVO4 and BiVO4/CF samples retained the monoclinic structure. From SEM, the CF sheets were visualized, covering the surface of BiVO4 particles. The specific surface area of the synthesized catalysts increased from 1.77 to 24.82 m2/g. The shift of absorption edge to a longer wavelength corresponded to a decrease in band gap energy from 2.3 to 2.2 eV. The photocatalytic degradation rate of the BiVO4/CF composite was five times higher than that of pristine BiVO4. Moreover, the photocatalyst can be separated and recycled with little change after the third times recycling. The improved activity of the composite resulted from the combination of the adsorption performance of the substrate CF and the photocatalytic activity of BiVO4. In addition, the position of the specific mechanism could occur via both the active species of superoxide radical and hydroxyl radical.

Preparation of Silver Decorated Reduced Graphene Oxide Nanohybrid for Effective Photocatalytic Degradation of Indigo Carmine Dye

Background: Even though silver decorated reduced graphene oxide (Ag-rGO) shows maximum absorptivity in the UV region, most of the research on the degradation of dyes using Ag-rGO is in the visible region. Therefore the present work focused on the photocatalytic degradation of indigo carmine (IC) dye in the presence of Ag-rGO as a catalyst by UV light irradiation. Methods: In this context, silver-decorated reduced graphene oxide hybrid material was fabricated and explored its potential for the photocatalytic degradation of aqueous IC solution in the UV region. The decoration of Ag nanoparticles on the surface of the rGO nanosheets is evidenced by TEM analysis. The extent of mineralization of the dye was measured by estimating chemical oxygen demand (COD) values before and after irradiation. Results: The synthesized Ag-rGO binary composites displayed excellent photocatalytic activity in 2 Χ 10-5 M IC concentration and 5mg catalyst loading. The optical absorption spectrum of Ag-rGO showed that the energy band-gap was found to be 2.27 eV, which is significantly smaller compared to the band-gap of GO. 5 mg of Ag-rGO was found to be an optimum quantity for the effective degradation of IC dye. The degradation rate increases with the decrease in the concentration of the dye at alkaline pH conditions. The photocatalytic efficiency was 92% for the second time. Conclusion: The impact of the enhanced reactive species generation was consistent with higher photocatalytic dye degradation. The photocatalytic mechanism has been proposed and the hydroxyl radical was found to be the reactive species responsible for the degradation of dye. The feasibility of reusing the photocatalyst showed that the photocatalytic efficiency was very effective for the second time.

Influence of the Local Structure on the Photocatalytic Properties of Zinc Spinel Ferrite Nanoparticles

The correlation between iron distribution in octahedral or tetrahedral sites in synthetic magnetite and zinc spinel ferrites and their catalytic properties were investigated in this work. The zinc-doped nanomagnetites were prepared by co-precipitation method and annealed at 420 °C. X-ray diffraction, UV-Vis, X-ray absorption and 57Fe Mössbauer spectroscopies were used to identify iron sites. The obtained results showed that ZnII replaces the relatively smaller FeIII cation in the tetrahedral sites, increasing the cubic lattice dimension, and this replacement remarkably enhances the catalytic effectiveness of the Zn-spinel ferrite towards the indigo carmine degradation compared to undoped magnetite. The indigo carmine degradation experiments were carried out using photo-Fenton method in which 50 mL of indigo carmine dye aqueous solutions (20 mg L−1, pH 3.0), 20 mg ZnxFe(3-x)O4, and 2.0 mL H2O2 (aqueous solution at 0.028 mol L−1) were placed under UV light at 25 °C. Under these experimental conditions the degradation rate of indigo carmine was superior to 98%.

ENHANCING THE DEGRADATION POTENTIAL OF INDIGO CARMINE BY A MEDIATED ELECTROCHEMICAL OXIDATION USING Ce4+ MEDIATOR AND Ag+ CATALYST IONS

Wastewater runoff containing hazardous dyes must be treated properly before being discharged into the environment. Indigo carmine (IC), a kind of dye, has been recognized to be potentially toxic. In this work, mediated electrochemical oxidation (MEO) using cerium (Ce4+) mediator ions incorporated with an Ag+ catalyst ion was tested to treat IC solution in a reactor as a simulation. The experimental results demonstrated that the IC molecules can be degraded quickly in a relatively short time by MEO. It was clearly shown that the degradation performance of IC by MEO was affected by the Ce2(SO4)3 concentration, working potential, time, and catalyst ion concentration as well. In addition, the high percentage recovery of Ce4+ proves the reusability of Ce4+ as a mediator ion. As an outstanding result, the percentage degradation of IC using Ce4+ /Ag+ ions was remarkably higher than that without Ce4+ mediator ions (100% vs 2%). In summary, our work suggests that MEO using a combination of Ce4+ mediator and Ag+ catalyst ion has great potential to improve the wastewater quality