Decolorization Reaction Research Articles

Kinetics of permanganate–sulfuric acid redox reaction with cetyltrimethylammonium bromide

AbstractThe permanganate–H2SO4 redox reaction, useful in oxidative treatments under aqueous conditions, was studied spectrophotometrically in the absence and presence of cetyltrimethylammonium bromide (CTAB). The decolorization reactions were influenced by the [MnO4−], [H2SO4], and temperature. Permanganate reduction follows first‐, and complex–order kinetics with permanganate, and H2SO4 concentrations, respectively. The reduction of permanganate (Mn(VII)) proceeds through a complex formation between MnO4− and H2SO4. The characteristic absorption peaks for MnO42− (λmax = 439 and 606 nm), MnO43− (λmax = 667 nm), and MnO2 (λmax = 400–418 nm) were not appeared during the redox reaction. The KMnO4 degradation efficiency remains unaffected with sodium pyrophosphate and sodium fluoride. The results of this study demonstrated the formation of Mn(II) as the stable product in acidic reaction media. The degradation efficiency increases drastically from 15 to 100% with 2.0 × 10−4 to 16.0 × 10−4 mol/L CTAB concentration under sub‐, and post‐micellar reaction conditions, respectively. The thermodynamic parameters (activation energy = 98.8 and 43.2 kJ/mol), activation of enthalpy (96.3, and 39.0 kJ/mol), activation of entropy (16.2 and −149.5 J/K/mol), free energy of activation (93.1 and 83.5 kJ/mol) were calculated without and with CTAB, respectively. Hence, CTAB can be exploited for its multifunctional applications, and specifically for the catalytic role in the permanganate‐assisted redox reactions in future.

Determination of Activation Energy from Decolorization Reactions of Synthetic Dyes by Fenton Processes Using the Behnajady–Modirshahla–Ghanbary Kinetic Model

Determination of Activation Energy from Decolorization Reactions of Synthetic Dyes by Fenton Processes Using the Behnajady–Modirshahla–Ghanbary Kinetic Model

Plasma Gel Matrix as a Promising Carrier of Epigallocatechin Gallate for Regenerative Medicine.

Plasma gel (PG) is a protein matrix prepared from platelet-poor plasma and can be utilized as a drug carrier for controlled release. We previously demonstrated its applicability as a carrier of polyphosphate. Epigallocatechin-3-gallate (EGCG) is the main flavonoid found in green tea and functions as a strong antioxidant. To explore the applicability of PG as an EGCG carrier, we examined the release of EGCG from the PG matrix using an in vitro system. Pooled platelet-poor plasma (PPP) was prepared from four healthy adult male donors, mixed with EGCG, and heated at 75 °C for 10 or 20 min to prepare the PG matrix. The PG-EGCG matrix was incubated in PBS at 37 °C, and the EGCG released into PBS was determined using spectrophotometry. The antioxidant capacity was determined based on the principle of the iodine decolorization reaction. EGCG precipitated and incorporated into the PG matrix during thermal preparation. Trypsin, used to simulate the in vivo degradation of PG, released EGCG from the PG matrix over time. The released EGCG maintained its antioxidant capacity during incubation. These results indicate that thermally prepared PG matrices can be utilized as a promising EGCG carrier in the fields of tissue engineering and regenerative medicine.

Sunlight-activated Mo-doped La2CuO4/rGO perovskite oxide nanocomposite for photocatalytic treatment of diverse dyes pollutant

The pristine La2CuO4, Mo-doped, and rGO-supported nanocomposites were fabricated by a simple Pechini route. FTIR and XRD analysis confirmed the fabrication of the perovskite structure. The XRD results exhibit that the prepared products have no impurities and the dopant element is successfully incorporated into the perovskite material. FESEM images exhibit the morphology of synthesized perovskite material. EDX data showed the existence of lanthanum, copper, molybdenum, carbon, and oxygen in grown material. The energy band gap of the rGO-based composite was narrow compared with other samples. The photodegradation capability of the rGO-base catalyst was achieved 99.4 % (MB), 98.8 % (MO), 99.35 % (MR), 98.7 % (RhB), and 99.6 % (SO) in 75 min under natural sunlight illumination. The scavenger experiment revealed that superoxide and hydroxyl radicals are active species during the decolorization reaction. Moreover, this catalyst is stable for six cycles. The synthesized perovskite is an effective material for water purification and environmental remediation.

The Optimization of Hydrodynamic Cavitation as an Advanced Oxidation Option for the Removal of Persistent Contaminants in Wastewater

Wastewater is increasingly becoming the primary source of potable water in many cities, thanks to the development of recycling facilities. Persistent contaminants such as dyes and perfluorinated compounds from textile industries as well as other contaminants necessitate the design of removal technologies to treat wastewater to reduce these chemicals before discharge or being used as feed to a potable water plant. Several chemical treatment techniques have been reported but the most utilized advanced chemical treatments lead to high costs and further environmental concerns. This study investigated an alternative approach to wastewater treatment using a hydrodynamic cavitation pilot plant combined with a venturi as a way to remove recalcitrant compounds. The optimization of the removal process was explored by testing the effect of orifices with size 2, 3, 4, 5, or 6 mm on the decoloration of orange II dye. The impact of the catalyst: iron(II); oxidizing agent: hydrogen peroxide; and contact time was evaluated to find the ideal conditions under which the removal of perfluorooctanoic acid (PFOA) could be achieved. The decoloration of 20 ppm of orange II dye in simulated industrial textile wastewater was achieved at 90% efficiency when the pressure at the inlet was maintained at 300 kPa, the temperature at 34 °C, the pH at 2, and the orifice size at 2 mm of diameter. The kinetic study proved the decoloration reaction was pseudo first order and the rate of decolourisation of orange II was 0.23/min.Ten parts per million of PFOA could not be degraded by free radical attack using advanced oxidation processes when the inlet pressure was maintained at 300 kPa, the temperature at 34 °C, the pH of 2, and the orifice diameter of 2 mm. This resistance to removal is due to the structure of PFOA which is made up of a fluorine ion which stabilizes the compounds by inductive effects while dye is made up of nitrogen ion and is compatible with the above removal methods. The study demonstrated that the combination of venturi and orifice requires the throat size of the venturi to be similar or equal to that of the orifice for better efficiency.

Non-thermal atmospheric-pressure positive pulsating corona discharge in degradation of textile dye Reactive Blue 19 enhanced by Bi2O3 catalyst

In this work, monoclinic Bi2O3 was applied for the first time, to the best of our knowledge, as a catalyst in the process of dye degradation by a non-thermal atmospheric-pressure positive pulsating corona discharge. The research focused on the interaction of the plasma-generated species and the catalyst, as well as the role of the catalyst in the degradation process. Plasma decomposition of the anthraquinone reactive dye Reactive Blue 19 (RB 19) was performed in a self-made reactor system. Bi2O3 was prepared by electrodeposition followed by thermal treatment, and characterized by x-ray diffraction, scanning electron microscopy and energy-dispersive x-ray techniques. It was observed that the catalyst promoted decomposition of plasma-generated H2O2 into •OH radicals, the principal dye-degrading reagent, which further attacked the dye molecules. The catalyst improved the decolorization rate by 2.5 times, the energy yield by 93.4% and total organic carbon removal by 7.1%. Excitation of the catalyst mostly occurred through strikes by plasma-generated reactive ions and radical species from the air, accelerated by the electric field, as well as by fast electrons with an energy of up to 15 eV generated by the streamers reaching the liquid surface. These strikes transferred the energy to the catalyst and created the electrons and holes, which further reacted with H2O2 and water, producing •OH radicals. This was indentified as the primary role of the catalyst in this process. Decolorization reactions followed pseudo first-order kinetics. Production of H2O2 and the dye degradation rate increased with increase in the input voltage. The optimal catalyst dose was 500 mg∙dm−3. The decolorization rate was a little lower in river water compared with that in deionized water due to the side reactions of •OH radicals with organic matter and inorganic ions dissolved in the river water.

Cater to the call of on-site, quantitative, and low-cost food formaldehyde detection: A paper-based sensor by timing Congo red decoloration

Given the illegal formaldehyde (FA) contamination in seafood/aqueous products, the instrument-free, chemical-free, low-cost sensor that enables on-site FA detection is of great interest. We have developed a paper-based analytical device (PAD) sensor to detect FA on-site for easy operation by integrating FA-responsive dye decoloration reaction on filter paper and timing decoloration time for quantitative signal interpretation. This innovative dry chemical PAD sensor can be easily prepared. The on-site FA detection is performed by dropping a drop of the sample into the sensor sampling zone and timing the decoloration time, respectively. The difference in decoloration time between a fictitious blank (5.0 μM) and an FA standard is proportional to the FA concentration in the range of 10–700 μM with a detection limit of 5.6 μM. The utility and effectiveness of this PAD sensor has been verified by applying it to seafood, paper cups, and water samples with the supports of official method validation.

Sintered magnesium ferrite particles in decolorization of anthraquinone dye AV 109: Combination of adsorption and fenton process

Magnesium ferrite (MgFe2O4) particles were synthetized by sol-gel method and used in the decolorization of the Acid Violet 109 (anthraquinone dye, AV109) water solutions' by combination of adsorption and heterogeneous Fenton process. The material's morphology and elemental analysis of the surface were revealed by Scanning electron microscopy and Energy Dispersive Spectroscopy (SEM/EDS). The X-Ray Diffraction (XRD) technique was used to analyze the crystallographic phase. In the first part of the decolorization experiment, the adsorption ability of the synthesized particles was investigated. During the adsorption study influence of pH was investigated. In the second part of the decolorization experiment, the effects of the various parameters on the Fenton process were studied such as the initial concentrations of hydrogen peroxide, dye, and magnesium ferrite particles. Influence of magnesium ferrite particles structure, pH value and reaction temperature were also investigated. The decolorization reaction was followed by UV-Visible (UV-Vis) spectrophotometry. At optimal conditions, the dye decolorization was 99.1% (55.4% by adsorption and 43.7% by the Fenton process). Both the adsorption and the Fenton process obey second-order kinetics.

Sintered magnesium ferrite particles in decolorization of anthraquinone dye AV109: Combination of adsorption and fenton process

Magnesium ferrite (MgFe2O4) particles were synthetized by sol-gel method and used in the decolorization of the Acid Violet 109 (anthraquinone dye, AV109) water solutions' by combination of adsorption and heterogeneous Fenton process. The material's morphology and elemental analysis of the surface were revealed by Scanning electron microscopy and Energy Dispersive Spectroscopy (SEM/EDS). The X-Ray Diffraction (XRD) technique was used to analyze the crystallographic phase. In the first part of the decolorization experiment, the adsorption ability of the synthesized particles was investigated. During the adsorption study influence of pH was investigated. In the second part of the decolorization experiment, the effects of the various parameters on the Fenton process were studied such as the initial concentrations of hydrogen peroxide, dye, and magnesium ferrite particles. Influence of magnesium ferrite particles structure, pH value and reaction temperature were also investigated. The decolorization reaction was followed by UV-Visible (UV-Vis) spectrophotometry. At optimal conditions, the dye decolorization was 99.1% (55.4% by adsorption and 43.7% by the Fenton process). Both the adsorption and the Fenton process obey second-order kinetics.

Оценка активности пероксидаз, содержащихся в различных растительных источниках

In this study, the decolorization reaction of aqueous solution bromophenol blue dye was carried out in the presence of hydrogen peroxide and peroxidase contained in the roots of horseradish (Armoracia rusticana), radish (Raphanus sativus var. radicula), yellow turnip (Brassica napobrassica), daikon (Raphanus sativus), black radish (Raphanus sativus ‘Niger’), green radish (Raphanus) or stalk of white cabbage (Brassica capitata). The reaction was carried out at an initial dye content of 25,1 μM, a hydrogen peroxide concentration of 0,4 mM, at t = 24 °C and pH 4,01, the peel of various vegetables was used as a source of peroxidase; it was inserted into the reaction without enzyme primary extraction. When using horseradish waste, black radish, white cabbage, turnips, it is possible to get the degree of decolorization of the dye in its aqueous solution by 95%. The maximum rate and Michaelis constants of the enzymatic reaction are calculated by the linearization method in the Linuiver – Burke coordinates. It is shown that the activity of peroxidase contained in the peel of black radish persists with an increase in temperature from 23 to 40 °С.

Enhancement of photochromic molecule decolorization by coating a thin Ti(O) layer over gold nanoparticles

Abstract Photochemical decolorization reaction of terarylenes with a hydroxy or a methoxy group is studied on the surface of gold nanoparticles (AuNPs)/TiO2 thin hybrid film. AuNPs were deposited on TiO2 film after UV irradiation with HAuCl4. The colored form of terarylenes could not be decolorized at the bare AuNPs on TiO2 under irradiation of green light (530 nm in wavelength). On the other hand, effective decolorization activity of terarylene, having a hydroxy group, was observed at the surface of AuNPs/TiO2 hybrid film with an optimized number of Ti(O) insulator layers on AuNPs. The mechanism for the enhanced decoloration is proposed based on the difference in the substituent of the terarylenes.

Macromolecular Design and Engineering of New Amphiphilic N-Vinylpyrrolidone Terpolymers for Biomedical Applications.

New amphiphilic VP-(di)methacrylate terpolymers of different monomer compositions and topologies have been synthesized by radical polymerization in toluene without any growth regulator of polymer chains. Their structures and properties in solid state and water solution were studied by double-detector size-exclusion chromatography; IR-, 1H, and 13C NMR-spectroscopy; DLS, TEM, TG, and DSC methods. The composition of the VP-AlkMA-TEGDM monomer mixture has been established to regulate the topology of the resulting macromolecules. The studied terpolymers presented on TEM images as individual low-contrast particles and their conglomerates of various sizes with highly ordered regions; in general, they are amorphous structures. None of the terpolymers demonstrated cytotoxic effects for noncancerous Vero and tumor HeLa cells. Hydrophobic D-α-tocopherol (TP) was encapsulated in terpolymer nanoparticles (NPs), and its antioxidant activity was evaluated by ABTS (radical monocation 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)) or DPPH (2,2'-diphenyl-1-picrylhydrazyl) methods. The reaction efficiency depends on the TP-NP type. The IC50 values for the decolorization reaction of ABTS•+ and DPPH inhibition in the presence of initial and encapsulated TP were obtained.

Facile auto-flash-combustion synthesis and characterization of visible-light-driven photocatalytic active Mn (II, III) loaded NiO nanoparticles

The opto-photocatalytic applications of Mn-doped NiO nanoparticles (NPs) are discussed. A facile synthesis of NiO doped with different Mn contents is performed and studied using experimental techniques. The structural properties and microstructural parameters of Mn:NiO NPs were examined by X-ray diffraction patterns. The average crystallite sizes of the pure NiO and 1.0-, 2.5-, 5.0-, 10-wt.% Mn-doped NiO NPs were found to be 25–19 nm by Williamson–Hall plots and 23–18 nm by the Debye–Scherer method. The crystallite size decreases with increasing doping concentration in the NiO host lattice. The optical bandgaps are found to be 3.53, 3.46, 3.39, 3.24, and 3.12 eV for pure NiO and 1.0-, 2.5-, 5.0-, and 10-wt.% Mn:NiO NPs, respectively, using the Kubelka–Munk function. X-ray photoelectron spectroscopy spectra of 2.5-wt.% Mn:NiO NPs were recorded for Mn, Ni, and O to determine the oxidation states. The photocatalytic performances of pure NiO and Mn:NiO NPs are examined. The 2.5-wt.% Mn:NPs exhibit the best photocatalytic performance owing to the greatest activation sites. The mechanism of the photocatalytic decolorization reaction is also investigated. The results demonstrate the high ability of Mn:NiO NPs as photocatalysts for methylene blue dye degradation, with 92% removal.

Zeolitic imidazolate framework biocomposite as a visible light-assisted photocatalyst: Synthesis (in-situ and blending), regeneration, and decolorization of Malachite Green

To overcome the limitations of current water treatment technologies, it is essential to develop non-toxic materials with high removal capabilities. Herein, novel green biocomposite beads, CS/ZIF-8/TiO2 (CZT), based on chitosan modified with zeolitic imidazolate framework (ZIF-8) and titania (TiO2) was introduced. The interesting and noteworthy features of this new biocomposite are its green synthesis, biocompatibility, and easy separation ability. The composite beads effectively decolorize Malachite Green (MG) dye solution using visible LED light. In the present study, the efficiency of three components of CZT biocomposite, which were synthesized by two different methods (in situ and blending), was compared to investigate the effect of the synthesis method, as well as the synthesis with two different amounts of TiO2 (0.2 g, and 0.4 g) to investigate the effect of TiO2. The prepared materials through the XRD, SEM, EDS, FTIR, DRS, TGA, and RAMAN analyses were characterized. The synergistic effect of ZIF-8, TiO2, and chitosan in the biocomposite increased the photo-decolorization ability of the MG dye under visible-light irradiation. The decolorization at the optimum pH (pH = 6.5) after 180 min reached 94.5% and at the natural pH (pH = 3.93) after 300 min reached 98.2%. The photocatalytic decolorization reaction of the biocomposite followed zero-order kinetics.

Use of Cu(II) catalyst assisted oxidative decolorization of dye by chlorinating species in water: A kinetic and mechanistic study with acid red1 dye

A quick and easy decolorization method has been created in the current study to get rid of the Acid Red 1 (AR1) dye from the wastewater. At 298 K, the kinetics of oxidative decolorization of AR1 dye with Chloramine-B (CAB) in NaOH medium, catalyzed by copper(II) sulphate, have been examined spectrophotometrically (λmax = 506nm). The experimental rate laws found are as follows: d[CAB]/dt = k [CAB]0 [AR1]0 [Cu(II)]x / [OH−]y in an alkaline medium, where x and y are less than unity.Under ideal experimental conditions, 90% dye decolorization is achieved in 30 minutes using concentrations of 0.003M [CAB], 0.0003M [AR1], 0.003M [Cu(II), and 0.003M [OH−].In the current kinetic redox system, the Cu(II) catalyst showed to be an effective homogeneous catalyst. The 4-acetamido-5,6-dioxo-5,6-dihydro naphthalene-2-sulphonic acid is identified as the oxidation product using mass spectrum analysis. The FTIR spectra show the absence of N=N stretching bands at 1489 cm−1 which confirms the oxidative breakdown of the azo group, a fundamental chromophore responsible for color, which induces toxicity in the waste water. The decolorization reaction catalyzed by Cu(II) is approximately six times faster than the uncatalyzed reaction. The catalytic constant (Kc) is calculated at various temperatures, and activation parameters for copper(II) are also evaluated. The observed results are explained by plausible mechanisms, and relative rate laws has been deduced. Chemical oxygen demand (COD) has been significantly reduced by the oxidative decolorization process. Phytotoxicity tests revealed that the treated dye sample is less toxic than the untreated dye sample. An economic analysis is carried out. Notably, with appropriate modifications, the developed oxidative decolorization technique is expected to benefit in the removal of AR1 dye present from industrial wastewater.

Evaluation of spatial distribution of the oxidation of glass beads simulating soil using high-voltage pulsed discharge

The spatial distribution of soil oxidation using a high-voltage pulse generator was evaluated using indigo carmine. The results showed that the amount of indigo carmine decolorization increased with increasing charging voltage and energy input. It was also found that the decolorization of indigo carmine occurred on the surface of the needle electrode, in the discharge path, and near the ground electrode. The probability of discharge penetrating soil increased with decreasing the gap length between the electrode tip and soil surface, which promoted the decolorization reactions. The amount of indigo carmine decolorization per volume decreased with increasing soil depth. When the soil depth was large, discharges reaching the ground electrode could not be confirmed. This suggests that the oxidation reaction of indigo carmine depends on a discharge that penetrates the soil.

Improving the Photocatalytic Performance of Porous Ceria under Visible Light Illumination via Mn Incorporation

Porous cerium oxide (ceria) nanoparticles were prepared with and without manganese (Mn) by using the flash combustion technique. Samples with different loadings (Ce/Mn ratio ranged from 100 to 10) were prepared by using a one-step process and water only as a solvent. Moreover, citric acid was utilized as a fuel in an aqueous medium, and the overall synthesis mixture was dried at 100 °C overnight and then calcinated at 550 °C for 3 h. The obtained final solid product was characterized by inductively coupled plasma (ICP), X-ray powder diffraction (XRD), diffuse reflectance ultraviolet-visible spectroscopy (DR-UV-Vis), and scanning electron microscopy (SEM), which was coupled with Energy Dispersive X-Ray Analysis (EDX), high resolution transmission electron microscopy (HR-TEM), and photoluminescence (PL) analysis. The characterization data showed that Mn ions were totally incorporated into the framework of ceria up to the applied loading. Under visible light illumination, the photocatalytic activity of the prepared samples was tested in the decolorization reaction of methyl green (MG) dye (wavelength greater than 425 nm). The results showed that increasing Mn content improved the photocatalytic activity of ceria. The sample with a Ce/Mn ratio of 10 performed 1.8 times better than bare porous ceria. Finally, the reusability of the best-performing sample was investigated in four consecutive runs without treatment, and slight deactivation was monitored after the fourth run.

Study on decolorization of methylene blue with a kind of electrolytic active water

Electrolytic active water was prepared by electrolytic treatment of sodium chloride aqueous solution using a self-made device. In order to investigate the properties of electrolytic active water , the pH value, available chlorine contents and decolorization ability on methylene blue solution were tested and compared with that of sodium hypochlorite aqueous solution. Experimental results showed that the electrolytic active water has higher oxidation capacity and decolorization efficiency for methylene blue compared with sodium hypochlorite solution, implying maybe other reactive oxygen species components besides hypochlorite existed in the electrolytic active water. The electrolytic active water was stable under long-term storage, and mechanical force with oxidation activity did not decrease. In addition, the decolorization kinetics of methylene blue in the electrolytic active water was explored, and it was found that, in general, the decolorization reaction of methylene blue in electrolytic active water was consistent with the first-order reaction kinetics model, but when the pH value of electrolytic active water solution was weakly alkaline or neutral, the decolorization reaction of methylene blue was closer to the second-order reaction kinetics model.

Decolorization of Direct Black 22 by Photo Fenton like Method Using UV Light and Zeolite Modified Zinc Ferrite: Kinetics and Thermodynamics.

In this study, a heterogeneous catalyst was prepared to enhance photo-Fenton like oxidation of Direct Black-22 (DB-22). Zeolite modified with zinc ferrite was used as a catalyst. The prepared catalyst was characterized using FTIR, SEM, EDS and XRD. The effect of various parameters like catalyst modification with HCl, H2O2 amount, catalyst amount, CaCl2 amount, initial pH, initial concentration and temperature on the decolorization of DB-22 was studied under UV light. Kinetic and thermodynamic properties were investigated. The highest decolorization of DB-22 was found to be 93.3% under the following conditions: initial concentration: 0.070 g/L, initial temperature: 25 °C, original pH, H2O2 amount: 2.78 g/L, m-ZZF amount: 3 g/L, CaCl2 amount: 3.75 g/L, reaction time: 60 min and UV light. The activation energy was found to be -14.76 kJ/mol under the studied conditions. The decolorization reaction was an exothermic reaction, and the calculated reaction enthalpy was -17.31 kJ/mol. The activation entropy was calculated to be -0.326 kJ/mol. The standard Gibbs free energy change of the activation had a positive value, and it increased with increasing temperature.

Novel bio-based Pd/chitosan-perlite composite bead as an efficient catalyst for rapid decolorization of azo dye

Perlite that is a volcanic glass was applied along with chitosan to form chitosan-perlite beads through a facile procedure. The as-prepared beads were then cross-linked with glutaraldehyde and utilized as a bio-based supporting material for the immobilization of Pd nanoparticles via wet impregnation method. The resultant catalyst was characterized via XRD, SEM, TEM, ICP, TGA, FTIR and elemental mapping analysis and its performance was then appraised for decolorization of Methyl orange dye in aqueous media at ambient temperature in the presence of sodium borohydride as a reducing agent. The results established that scant amount of the catalyst, 1.5 mg, could promote the reaction in 2 min to decolorize the dye with yield = 100 %. Using the experimental data, activation energy, enthalpy, and entropy of the decolorization reaction were calculated to be 35.98 kJ/mol, 33.44 kJ/mol, −166.22 J/mol.K, respectively. The catalyst was recyclable up to eight runs with insignificant loss of catalytic activity and Pd leaching.