Dye In Aqueous Solution Research Articles

Fabrication of activated carbon from polyethylene terephthalate plastic waste (PET) and their application for the removal of organic dyes in aqueous solution by chemical method

Synthetic plastics are found in all manufacturing industries and in daily life because plastic products bring convenience to life. Polyethylene terephthalate (PET) is one of the most popular synthetic plastics with increasing consumption. Every year, the huge amount of PET plastic waste is discharged into the environment. Therefore, it is necessary to have an effective solution for PET plastic waste. In this study, PET waste plastic was utilized to fabricate activated carbon using the chemical activating approach. H3PO4 acid was used as activating agent. The influence of impregnation rate of PET waste platic with H3PO4, activating temperature, activating time on the surface areas of activated carbon was investigated. The prepared activated carbon was well-characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), FTIR, and BET. The activated carbon prepared from the :PET plastic waste revealed high absorption toward methylene blue in aqueous solution in a wide range of pH solutions. The fabrication of activated carbon from the plastic waste not only address the environmental issues, but also produce high-value activated carbon for the environmental remediation.

Impact of Copper(II)-Imidazole Complex Modification on Polycrystalline TiO2: Insights into Formation, Characterization, and Photocatalytic Performance

Micrometer-sized polycrystalline anatase particles are widely used in materials and life sciences, serving as essential components in photocatalytic materials. The ability to tailor their composition, shape, morphology, and functionality holds significant importance. In this study, we identified and examined the non-destructive route of Copper(II) implantation at the surface of polycrystalline TiO2. The [Cu(en)(Im)2]2+ complex ion demonstrated a remarkable affinity to concentrate and bind with the semiconductor’s surface, such as anatase, forming a surface-bound adduct: ≡TiO2 + [Cu(en)(Im)2]2+ → ≡TiO2//[Cu(en)(Im)2]2+. The misalignment of Fermi levels in TiO2//[Cu(en)(Im)2]2+ triggered electron transfer, leading to the reduction of the metal center, releasing Copper(I) in the process. Although less efficient, the released Copper(I) encountered a highly favorable environment, resulting in the formation of the surface complex TiO2:CuIIsc. The implanted Cu(I) was converted back into Cu(II) due to re-oxidation by dissolved oxygen. The penetration of the metal ion into the surface level of the polycrystalline TiO2 lattice was influenced by surface residual forces, making surface grafting of the Cu(II) ion inevitable due to surface chemistry. FTIR, UV–vis, Raman, XRD, EPR, and surface morphological (SEM, EDAX, and HRTEM) analyses identified the typical surface grafting of the Cu(II) cluster complex on the anatase surface matrix. Moreover, the XRD results also showed the formation of an impure phase. The TiO2 polycrystalline materials, modified by the incorporation of copper complexes, demonstrated an enhanced visible-light photocatalytic capability in the degradation of Rhodamine B dye in aqueous solutions. This modification significantly improved the efficiency of the photocatalytic process, expanding the applicability of TiO2 to visible light wavelengths. These studies open up the possibility of using copper complexes grafted on metal oxide surfaces for visible-light active photocatalytic applications. Moreover, this investigation not only showcases the improved visible-light photocatalytic behavior of copper-modified TiO2 polycrystalline materials, but also underscores the broader implications of this improvement in the advancement of sustainable and efficient water treatment technologies.

Biogenic synthesis, characterization and photocatalytic activity of cerium nanoparticles for treatment of dyes contaminated water

In this study, Murraya Koenigii leaf extract mediated cerium oxide nanoparticles (Ce-NPs) were synthesized using an eco-friendly approach. The surface morphology, elemental composition, surface functional groups, crystal structure and thermal stability of the synthesized Ce-NPs were examined using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD) and thermogravimetric (TGA) analysis. The synthesized Ce-NPs were evaluated for their photocatalytic activity with respect to degradation of methylene blue dye (MBD) and acid orange-7 dye (AO7D) aqueous solution in the presence of sunlight. The dye degradation activity of the developed Ce-NPs was analyzed by the analysis of absorbance in treated and untreated aqueous dyes solution using UV–Vis spectrophotometer. The result of the study inferred that Ce-NPs have promising photocatalytic degradation ability (>98 %) for both AO7D and MBD (concentration = 10 mg L−1 of each dye) within 100 min exposure to sunlight.

Synthesis, characterization and analysis of conducting polymer composites toward dye adsorption

The present effort reports on the synthesis of novel and recyclable polymer-based adsorbents based on polypyrrole (PPy) and polyethyleneimine (PEI) for the removal of cationic crystal violet (CV) dye from aqueous solutions. The characterization of the composites was determined by FTIR, XRD, FESEM, and XPS techniques. The effects of different variables on the adsorption of crystal violet dye were studied, including the pH, adsorbent doses, and contact time. The research findings show that the different oxidants used to prepare polypyrrole in PPy-PEI adsorbents play a vital role in CV dye adsorption. The PPy-PEI composite prepared by using the ammonium persulfate oxidant was found to exhibit the highest adsorption of 70.9% among the three different oxidants, namely, anhydrous ferric chloride, ferric chloride hexahydrate, and ammonium persulfate. The ideal adsorption conditions for the removal of CV dye were discovered using an adsorbent dosage of 0.3 g at pH 11, with a contact time of 180 min. Kinetic regression analysis indicated that the adsorption processes followed the pseudo-second order kinetic model and fit well with the Langmuir isotherm, with a maximum monolayer sorption capacity of 142.86 mg/g at a temperature of 27 °C. In addition, the regeneration of the PPy-PEI composite was accomplished with dye adsorption efficiency decreasing from 70.9% to 64.4% after three adsorption-desorption cycles. The present work suggests that the PPy-PEI composite is a promising adsorbent for removing cationic CV dye in aqueous solutions.

UV-blocking and photocatalytic properties of Ag-coated cotton fabrics with Si binders for photo-degradation of recalcitrant dyes in aqueous solutions under sunlight

Textile wastewater laden with dyes has emerged as a source of water pollution. This possesses a challenge in its effective treatment using a single functional material. In respond to this technological constraint, this work presents multifunctional cotton fabrics (CFs) within a single, streamlined preparation process. This approach utilizes the adherence of Ag NPs (nanoparticles) using Si binder on the surface of CFs, resulting in Ag-coated CFs through a pad dry method. The prepared samples were characterized using scanning electron microscope-energy dispersive X-ray electroscopy (SEM-EDS), thermal gravimetric analysis (TGA), Fourier transformation infrared (FT-IR). It was found that the FT-IR spectra of Ag NPs-coated CFs had peaks appear at 3400, 2900, and 1200 cm−1, implying the stretching vibrations of O–H, C–H, and C–O, respectively. Based on the EDX analysis, the presence of C, O, and Ag related to the coated CFs were detected. After coating the CFs with varying concentrations of Ag NPs (1%, 2% and 3% (w/w)), they were used to remove dyes. Under the same concentration of 10 mg/L and optimized pH 7.5 and 2 h of reaction time, 3% (w/w) Ag-coated CFs exhibited a substantial MB degradation of 98 %, while removing 95% of methyl orange, 85% of rhodamine B, and 96% of Congo red, respectively, following 2 h of Vis exposure. Ag NPs had a strong absorption at 420 nm with 2.51 eV of energy band gap. Under UV irradiation, electrons excited and produced free radicals that promoted dyes photodegradation. The oxidation by-products included p-dihydroxybenzene and succinic acid. Spent Ag-coated CFs attained 98% of regeneration efficiency. The utilization of Ag-coated CFs as a photocatalyst facilitated treated effluents to meet the required discharge standard of lower than 1 mg/L mandated by national legislation. The integration of multifunctional CFs in the treatment system presents a new option for tackling water pollution due to dyes.

Highly Efficient Performance of Gamma-Irradiation on the Decolorization and Degradation of Sunset Yellow Dye in Aqueous Solutions

Highly Efficient Performance of Gamma-Irradiation on the Decolorization and Degradation of Sunset Yellow Dye in Aqueous Solutions

APLICAÇÃO DA LAMA DE BENEFICIAMENTO DE ROCHAS ORNAMENTAIS COMO CATALISADOR NO PROCESSO FOTO FENTON PARA A DESCOLORAÇÃO DE CORANTE EM SOLUÇÃO AQUOSO

APPLICATION OF ABRASIVE MUD FROM THE PROCESSING OF ORNAMENTAL ROCKS AS A CATALYST IN THE PHOTO FENTON PROCESS FOR THE DECOLORIZATION OF DYE IN AQUEOUS SOLUTION. The extraction and processing of ornamental rocks generate a very significant amount of waste, representing an environmental and public health problem. The residue is a fine-grained compound by rock powder and inputs used in the processing process have a potential economic value. The present study was carried out to evaluate the efficiency of the waste generated in the discoloration of an aqueous solution containing methylene blue dye, such as alternative for treating textile effluents. The samples were characterized by X-ray diffraction, inductively coupled plasma optical emission spectroscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. The catalytic properties of the samples were evaluated in the Fenton and photo Fenton reactions at pH 3 and natural pH. The best decolorization efficiency (≈ 95%) was achieved using the GRM catalyst at pH 3, after 5 min of photo Fenton reaction. Importantly, owing to its excellent structural and chemical stability, the samples showed a decolorization efficiency above 95% after 5 consecutive cycles of 30 min of reaction. This innovative strategy not only offers a new prospect for the rational disposal of abrasive mud waste, but also contributes to minimizing environmental impacts, promoting sustainable development in the stone industry.

Magnetized cubic zinc MOFs for efficient removal of hazardous cationic and anionic dyes in aqueous solutions.

A significant amount of dye runoff and aqueous waste are released from the manufacturing process of dyes with intense and permanent colors, which are undesirable from a cultural and ecological aspect. In this paper, we present a green, simple, low-effort, and energy-efficient method of creating magnetized cubic Zn-MOFs for the adsorption and elimination of various organic dyes. Magnetic iron oxide materials with a hierarchical structure were loaded and doped into cubic zinc metal-organic frameworks (MDLZ). High magnetic characteristics, chemical stability, minimal toxicity, and ease of removing various dyes from aqueous effluents are all exhibited by the developed MDLZ adsorbent. To assess MDLZ's capacity to adsorb organic dyes from an aqueous solution, organic dyes such as Crystal Violet (CV), Neutral Red (NR), and Congo Red (CR) were used as model materials. Many adsorption factors were examined, including temperature, pH, contact time, initial concentration, and adsorbent dosage. Under optimal elimination circumstances, MDLZ was utilized to evaluate the kinetic, thermodynamic, and isotherm models for the adsorption of CR, NR, and CV dyes. The adsorption capacity (q m) of the MDLZ adsorbent at 25 °C was 39.37 mg g-1 for CV, 239.81 mg g-1 for CR, and 321.54 mg g-1 for NR, which is significantly higher than those of other adsorbents reported. The magnetized nanocubes' large surface area and uniform micropores enabled them to eliminate a large number of organic dyes from wastewater effectively, and their strong adsorption capability persisted even after four reuse cycles. The microporous MLDZ adsorbent offers a simple and effective method for handling industrial effluents and filtration of water.

Facile chemically activation process of kapok husk as a low-cost biosorbent for removal methylene blue dye in aqueous solution

This study discusses kapok husk (KH) activated by HNO3 as a biosorbent for methylene blue dye and analyses its adsorption ability. The adsorption capacity of KH is 330.161 mg g-1 with optimum conditions at pH 9, concentration 5500 mg L-1, contact time 15 min, and biosorbent temperature 25?C. The isotherm study followed the Langmuir isotherm model, as seen from the R2 value of 0.9993 and maximum adsorption capacity of 312.5 mg g-1, which indicated a monolayer in the adsorption process. The kinetic data show that KH followed the pseudo-second-order model. The results of the TGA analysis show that thermal stability affects the performance of biosorbents in the adsorption process. FTIR and SEM-EDS characterisation results showed that electrostatic interactions, cation exchange, and pore filling regulate the methylene blue dye adsorption mechanism on the surface of the KH. The reusability of KH through adsorption?desorption cycle analysis was achieved five times. This indicates that the biosorbent can be economically feasible for real wastewater treatment based on its good reusability and simple preparation and activation.

Understanding the role of solvents in bottom-up synthesis of multi-element hydroxides.

Here we report a comparative study on the bottom-up synthesis of multi-element hydroxides composed of Mg, Al, Fe and Zn cations to understand the role of solvents. Two common solvents, water and ethylene glycol, a typical polyol, are used. The polyol-derived MgAlFeZn-OH are nanosheets with homogeneous elemental distribution, while the hydrothermal-derived MgAlFeZn-OH are mixtures of plate-like hydroxide layers and rod-like spinel oxides. The coordinating properties and the high viscosity of the ethylene glycol provide the possibility to mediate the hydrolysis rates and to control the particle growth. The high specific surface area of the polyol-derived multi-element hydroxide nanosheets (352.4 m2 g-1) guarantees them as excellent adsorbents for adsorbing anionic dyes in aqueous solution.

A Novel Recyclable Magnetic Nano-Catalyst for Fenton-Photodegradation of Methyl Orange and Imidazole Derivatives Catalytic Synthesis.

A magnetite chlorodeoxycellulose/ferroferric oxide (CDC@Fe3O4) heterogeneous photocatalyst was synthesised via treated and modified cotton in two steps. The designed nanocomposites were characterised by FTIR, TGA, XRD, SEM, and VSM analyses. The Fenton-photocatalytic decomposition efficiency of the synthesised magnetic catalyst was evaluated under visible sunlight using Methyl Orange (MO) as a model organic pollutant. The impacts of several degradation parameters, including the light source, catalyst load, irradiation temperature, oxidant dose, and pH of the dye aqueous solution and its corresponding concentration on the Fenton photodegradation performance, were methodically investigated. The (CDC@Fe3O4) heterogeneous catalyst showed a remarkable MO removal rate of 97.9% at 10 min under visible-light irradiation. (CDC@Fe3O4) nanomaterials were also used in a heterogeneous catalytic optimised protocol for a multicomponent reaction procedure to obtain nine tetra-substituted imidazole derivatives. The green protocol afforded imidazole derivatives in 30 min with good yields (91-97%) at room temperature and under ultrasound irradiation. Generally, a synthesised recyclable heterogeneous nano-catalyst is a good example and is suitable for wastewater treatment and organic synthesis.

CINETIC STUDY OF PHOTOCATALYTIC DEGRADATION BY THE (TIO2/UV) SYSTEM OF INDIGO CARMINE DYE IN AQUEOUS SOLUTION

The persistence of synthetic dyes in the environment and the ineffectiveness of most conventional depollution techniques have led the scientific community to turn to advanced oxidation processes for eliminating these dyes from water. The aim of this work was to experiment with heterogeneous photocatalysis in the degradation of indigo dye in aqueous solution. The catalyst used was titanium dioxide in the anatase PC 500 form, irradiated by a polychromatic ultraviolet lamp with a wavelength λ= 365 nm. This technique proved effective, with a 77% degradation rate compared with photolysis, which removed only 17% of the indigo dye under the same conditions. Also, this work showed that low-concentration solutions were easily degraded with total decolourisation of the 12 mg/L molecule after 4 hours compared with 80% elimination of the 32 mg/L solution.The study of the influence of light intensity showed an increase in the rate of degradation of the molecule when the number of lamps placed in the reactor was increased. Total degradation was observed when 4 lamps were used for 120 minutes of irradiation.

Coal fly ash-supported ZnO-promoted TiO2 towards UV photocatalytic degradation of anthraquinone dye: Parametric optimization, kinetics and mechanism studies

Heterogeneous photocatalysis via combination of catalyst and UV irradiation is one of the most promising advanced oxidation processes for degradation of water-soluble organic contaminants. Herein, different photocatalysts (ZnO/CFA, TiO2/CFA, and TiO2-ZnO/CFA) were synthesized via sol-gel and impregnation techniques and applied for the degradation of acid blue 25 (AB25) dye in aqueous solution under UV light in a photoreactor. Various spectroscopic techniques (XRF, XRD, BET, FTIR, UV–vis DRS, TEM and EDS) were employed to evaluate the chemical structure, functional groups, textural, and optical properties of the binary and ternary composites. TiO2-ZnO/CFA displayed rapid degradation of AB25 as compared to ZnO/CFA and TiO2/CFA, owing to the dualistic photocatalytic sites. The prepared TiO2-ZnO/CFA composite was used in synergy with the photoreactor for photocatalytic degradation process optimization, and the optimum degradation conditions in relation to initial AB25 concentration (10 mg/L), UV light intensity (18 W/m2), flow rate (12.5 L/h), and irradiation time (150 min) as input parameters were determined using Taguchi design approach. The maximum photocatalytic degradation efficiency was 98.79±0.94% under those aforementioned conditions, indicating that the synergies between the photoreactor and the TiO2-ZnO/CFA photocatalyst resulted in the effective destruction of AB25 dye molecules. Furthermore, the spent photocatalyst was easily removed from the degraded solution and reused up to nine times. After 150 mins of UV irradiation with TiO2-ZnO/CFA photocatalyst, almost complete mineralization of AB25 solution was achieved.

Organically modified montmorillonite as an environmental adsorbent of pollutants: Formaldehyde from urea-formaldehyde resin and Acid Red 183 dye from the aqueous solution

In this research, a composite based on montmorillonite (K10) modified with HDTMABr was used. The characterization of the pure K10, NaMMT and OMMT was performed using XRD, FTIR-ATR, SEM, TG, DTG, and DTA. Ion exchange capacity (CEC) and specific surface area (SSA) were also determined. The sulfite method was used to determine free and liberated formaldehyde (FA) from synthesized urea-formaldehyde/montmorillonite (UF/MMT) composites. This research aims to demonstrate the bifunctionality of OMMT and that it can be used both for the capture of FA from the synthesized cross-linked UF resin and for the adsorption of the anionic dye Acid Red 183 (AR183) from aquatic medium. SEM analysis showed that there are changes in the morphology of the OMMT and the formation of a hollow network, which affects the absorption capacity of the clay. The calculated values of free and liberated FA in the UF/OMMT composites are drastically reduced and amount to 0.12% and 0.96%, respectively, compared to the composites with K10 (0.6% and 2.04%, respectively). Also, very promising results were obtained of the adsorption of AR183 dyes from the aquatic medium using OMMT. The results show that OMMT (0.5 g OMMT/50 cm3 aqueous dye solution, c=20 mgdm−3) managed to remove 85.95% of AR183 dye (pH dye=7). The adsorption mechanism of AR183 on OMMT follows the Freundlich isotherm and proceeds according to the pseudo-first-order kinetic model. Overall, the findings of this work indicate that the use of the obtained OMMT has great potential in removing pollutants from two totally different systems.

Wood Colouring with Natural Dye Extracts. New Research and Perspectives

The aims of the present research were to test new types of natural dye extracts for wood as a possible alternative to synthetic dyes and to evaluate the colour changes after a period of one year of exposure to natural light, in indoor conditions. Three types of extracts using raw materials: nutshell from Juglans regia L. (E1), onion peels (E2), and dry plant of Chelidonium majus L. (E3) were employed. Spruce wood (Picea abies L. Karst) samples with dimensions of (120x80x5) mm were used. The dye aqueous solutions with a concentration of 5% (E1, E3) and 2.5% (E2) were obtained by solid-liquid extraction at 100°C for three hours. The extracts E1, E2, E3 were modified by the addition of mordant ferrous sulphate Fe2(SO4)3 3% and coded EM1, EM2, EM3 respectively. The wood was coloured by dipping procedure at 60° C for 30 min. Three replicates were employed for each type of dye solution. After conditioning, two replicates together with the uncoloured samples (M) were further exposed indoors, and one coloured sample remained unexposed, as a control. Colour measurements in the CIELab system were performed before and after each period of exposure (30, 60, and 365 days), and the colour differences ΔL, Δa, Δb, and ΔE were calculated. Generally, all the samples dyed with natural extracts had fewer colour differences compared with the uncoloured wood. The lower value for colour change was registered for the E2 extract, followed by the E3, and E1 extract, respectively. According to the exposure time, the colour differences values ΔE range correspond to a medium colour up to different colours in visual perception. For mordant dye extracts EM1, EM2, and EM3 the results indicated a different colour in visual perception. The ΔE values registered were even higher than the uncoloured samples (M). The results were in accordance with similar research in the field. The present study opens new research opportunities in wood finishing and new colouring perspectives with eco-friendly dyes.

Design and Fabrication of Biomass Derived Black Carbon Modified g‐C3N4/FeIn2S4 Heterojunction as Highly Efficient Photocatalyst for Wastewater Treatment

AbstractThe environmental deterioration caused by dye wastewater discharge has received considerable attention in recent decades. One of the most promising approaches to addressing the aforementioned environmental issue is the development of photocatalysts with high solar energy consumption efficiency for the treatment of dye‐contaminated water. In this study, a novel low‐cost π–π biomass‐derived black carbon modified g‐C3N4 coupled FeIn2S4 composite (i.e., FeInS/BC‐CN) photocatalyst is successfully designed and fabricated that reveals significantly improved photocatalytic performance for the degradation of Eosin Yellow (EY) dye in aqueous solution. Under dark and subsequent visible light irradiation, the amount optimized composite reveals 99% removal performance for EY dye, almost three‐fold compared to that of the pristine FeInS and BC‐CN counterparts. Further, it is confirmed by means of the electron spin resonance spectrometry, quenching experiments, and density functional theory (DFT) calculations, that the hydroxyl radicals (•OH) and superoxide radicals (•O2−) are the dominant oxidation species involved in the degradation process of EY dye. In addition, a systematic photocatalytic degradation route is proposed based on the resultant degradation intermediates detectedduring liquid chromatography tandem mass spectrometry (LC‐MS/MS) analysis. This work provides an innovative idea for the development of advanced photocatalysts to mitigate water pollution.

Evaluation of mutagenic activity of the food dye Ponceau 4R in a micronuclear test in mice

Introduction. Food monoazo dye E124 Ponceau 4R is used in the food, pharmaceutical, and cosmetic industries. An analysis of the available data on the evaluation of the genetic safety of E124 based on the main marker events of genotoxicity revealed their inconsistency, possibly associated with quantitative and/or qualitative differences in the studied samples for impurities. 
 The aim of the work is to evaluate the mutagenic activity in the micronucleus test in mice of several commercial samples of E124 present on the domestic market.
 Materials and methods. Three samples of E124 from different manufacturers (India) were studied. To assess the identity of Ponceau 4R substances, there was used method of MIR-spectroscopy – universal ART technique. Aqueous dye solutions were administered to the stomach of male CBA × C57Bl6/j) mice at doses 
 of 125 to 2000 mg/kg twice with an interval of 24 hours and preparations were prepared 24 hours after the last injection. To assess the frequency of polychromatophilic erythrocytes (PCE) with micronuclei (MN), 4000 PCE were analyzed, the proportion of PCE among all erythrocytes – 500 cells per animal.
 Results. Ponceau 4 R was determined in all samples. All E124 samples caused an increase in the frequency of PCE with MN (p < 0.05–0.001, T test) after exposure at all levels studied in a linear dose-dependent manner. The proportion of PCE from all erythrocytes did not change. 
 Limitations. The data obtained do not allow determining the mechanism of the genotoxic action of the test substance.
 Conclusion. An analysis of the frequency of MN PCEs in the bone marrow in mice after a double injection at doses of 125–2000 mg/kg revealed the genotoxicity of three samples Ponceau 4R.

Photocatalytic degradation of methylene blue dye from aqueous solution using TiO2 doped Activated carbon

The effluent coming out from the textile, paper and food industries containing dye is strongly coloured and reveals very harmful effects on living beings. In order to reduce wastewater pollution, the degradation of dye into non-toxic form is desirable. The photo catalytic degradation of methylene blue is reported in the present study. The irradiation of aqueous solution of methylene blue dye in presence of photo catalyst and UV light was carried out in the batch photo reactor. Titanium dioxide TiO2 /CFAC was used as photo catalyst for the study. The rate of decolorisation was estimated from residual concentration spectrophotometrically. Effects of various operating parameters such as the irradiation time, initial pH and the amounts of catalyst on the degradation of the dyes were investigated. Results show that the degradation kinetics fitted well to pseudo second order rate law. The maximum decolorizing efficiency occurred in less than 50min with 50mg of TiO2 /CFAC catalyst dose.

Fenton-Like Oxidation Systems for Destruction of Azo Dyes in Aqueous Solutions

The kinetic regularities of degradation of the azo dye methyl orange (MO) in photoinitiated oxidizing systems have been studied using a xenon lamp (UV–Vis) as a source of quasi-solar radiation. According to the efficiency and rate of dye destruction, the considered oxidizing systems can be arranged in the following series: {UV–Vis} {UV–Vis/S2O2-8} {S2O2-8/Fe0} {UV–Vis/S2O2-8/Fe0} {UV–Vis/S2O2-8/Fe2+}. It has been established that in photoinitiated Fenton-like oxidizing systems there is not only complete conversion of MO but also its deep mineralization in aqueous solution; a decrease in the content of total organic carbon reaches 60%. In this case, the specific catalytic activity of iron ions in the combined system {UV–Vis/S2O2-8/Fe0} is much higher than in {UV–Vis/S2O2-8/Fe2+}. Using inhibitors of radical reactions, it has been proved that in the combined system {UV–Vis/S2O2-8/Fe0} both hydroxyl and sulfate anion radicals take part in oxidative degradation. An inhibitory influence of anions (bicarbonates, chlorides, nitrates, and sulfates) and natural dissolved organic matter (Suwanee River 2R101N) on the process of mineralization of total organic carbon during oxidative destruction of MO in the combined system {UV–Vis/S2O/Fe0} has been found.

Fenton-Like Oxidation Systems for Destruction of Azo Dyes in Aqueous Solutions

Fenton-Like Oxidation Systems for Destruction of Azo Dyes in Aqueous Solutions