Oxidation Of Orange Research Articles

Synthesis and characterization of Co(II) porphyrin complex supported on chitosan/graphene oxide nanocomposite for efficient green oxidation and removal of Acid Orange 7 dye

Catalytic degradation of Acid Orange 7 (AO7) by hydrogen peroxide in an aqueous solution has been investigated using cobalt(II) complex of 5, 10, 15, 20 Tetrakis [4-(hydroxy)phenyl] porphyrin [Co(II) TPHPP] covalently supported chitosan/Graphene Oxide nanocomposite [Co(II) TPHPP]-Cs/GO, as highly efficient and recoverable heterogeneous catalyst. The structures and properties of [Co(II) TPHPP]-Cs/GO nanocomposite were characterized by techniques such as UV–Vis, FT-IR, SEM, EDX, TEM, and XRD. The oxidation reaction was followed by recording the UV–Vis spectra of the reaction mixture with time at λmax = 485 nm. [Co(II) TPHPP]-Cs/GO nanocomposite demonstrated high catalytic activity and could decompose 94% of AO7 within 60 min. The factors that may influence the oxidation of Acid Orange 7, such as the effect of reaction temperature, pH, concentration of catalyst, Acid Orange 7, and hydrogen peroxide, have been studied. The results of total organic carbon analysis (TOC) showed 50% of dye mineralization under mild reaction conditions of AO7 (1.42 × 10−4M) with H2O2 (8 × 10−2M) in the presence of [Co(II) TPHPP]-Cs/GO nanocomposite (15 × 10−3 g/ml) and pH = 9 at 40 °C. The reuse and stability of the nanocomposite were examined and remarkably, even after six cycles of reuse, there was no significant degradation or deactivation of the recycled catalyst. Residual organic compounds in the reaction mixture were identified by using GC–MS analyses. The radical scavenging measurements and photoluminescence probing technology of disodium salt of terephthalic acid indicated the formation of the hydroxyl radical as the reactive oxygen species in the [Co(II) TPHPP]-Cs/GO nanocomposite/H2O2 system. A mechanism for the oxidation reaction has been discussed.

Enhancing of methyl orange oxidation using nanotube sensor: analytical application in water

Enhancing of methyl orange oxidation using nanotube sensor: analytical application in water

Assessing the Relationship between Indexed Epicardial Adipose Tissue Thickness, Oxidative Stress in Adipocytes, and Coronary Artery Disease Complexity in Open-Heart Surgery Patients.

Background and Objectives: This cross-sectional study conducted at the Timișoara Institute of Cardiovascular Diseases, Romania, and the Centre for Translational Research and Systems Medicine from "Victor Babeș" University of Medicine and Pharmacy of Timișoara, Romania, investigated the relationship between indexed epicardial adipose tissue thickness (EATTi) and oxidative stress in epicardial adipose tissue (EAT) adipocytes in the context of coronary artery disease (CAD) among open-heart surgery patients. The objective was to elucidate the contribution of EATTi as an additional marker for complexity prediction in patients with CAD, potentially influencing clinical decision-making in surgical settings. Materials and Methods: The study included 25 patients undergoing cardiac surgery, with a mean age of 65.16 years and a body mass index of 27.61 kg/m2. Oxidative stress in EAT was assessed using the ferrous iron xylenol orange oxidation spectrophotometric assay. The patients were divided into three groups: those with valvular heart disease without CAD, patients with CAD without diabetes mellitus (DM), and patients with both CAD and DM. The CAD complexity was evaluated using the SYNTAX score. Results: The EATTi showed statistically significant elevations in the patients with both CAD and DM (mean 5.27 ± 0.67 mm/m2) compared to the CAD without DM group (mean 3.78 ± 1.05 mm/m2, p = 0.024) and the valvular disease without CAD group (mean 2.67 ± 0.83 mm/m2, p = 0.001). Patients with SYNTAX scores over 32 had significantly higher EATTi (5.27 ± 0.66 mm/m2) compared to those with lower scores. An EATTi greater than 4.15 mm/m2 predicted more complex CAD (SYNTAX score >22) with 80% sensitivity and 86% specificity. The intra- and interobserver reproducibility for the EATTi measurement were excellent (intra-class correlation coefficient 0.911, inter-class correlation coefficient 0.895). Conclusions: EATTi is significantly associated with CAD complexity in patients undergoing open-heart surgery. It serves as a reliable indicator of more intricate CAD forms, as reflected by higher SYNTAX scores. These findings highlight the clinical relevance of EATTi in pre-operative assessment, suggesting its potential utility as a prognostic marker in cardiac surgical patients.

Effect of the Magnetostriction Induced on the Crystalline Structure of Nanoparticulate TiO2 Films Supported on Stainless Steel Mesh Electrodes and Their Relationship with the Photocatalytic Decoloration of Aqueous Orange G Solutions

The study of ferromagnetism (FM) in non-cubic semiconductor oxides such as defective TiO2 is attractive due to their applications in photocatalysis [1]. FM can be activated in TiO2 nanomaterials by promoting oxygen vacancies (VO) located in paramagnetic defected sites Ti3+VOTi4+. In this context, the VO can induce in Ti3+-doped TiO2 structures remarkable magnetic anisotropy energy (MAE) of 6.51x106 erg/cm3, thus indicating the magnetic saturation should be achieved at magnetic fields (MFs) of ~425 gauss [2,3]. Therefore, magnetostriction can be observed in ferromagnetic TiO2 films as a phenomenon in which their dimensions and shapes are changed when they are magnetized. In this work, stainless steel mesh electrodes (ss) were modified by nanoparticulate TiO2 films (ssTiO2) enriched by Ti3+VOTi4+ sites, to gain an understanding of the effects of magnetostriction on the photocatalytic properties of ferromagnetic TiO2 electrodes. In this way, MFs having intensities (H) of 125, 250, 500, 1000, and 2000 gauss were applied to the ssTiO2 electrodes for 80 min under UV light illumination for increasing the number of Ti3+VOTi4+ sites. Our results revealed that the magnetic lines promoted compression of the TiO2 structure when achieving pressures p>4.67 GPa for H>425 gauss in p=1/2(MAE/4p gauss2)H 2. Consequently, the degree of disorder (0<b<1) of the electron traps at the intra-bandgap state's distribution along the thickness-axis(i.e. the x-axis) of TiO2 films decreased significantly because the fraction of trapped electrons f trap(x) at the quasi-Fermi level EF(x) was maximized according to f trap(x)=m[em (E F (x)-E F (0))-1], where m=kT/b (k and T are the Boltzmann constant and the absolute temperature) [4,5]. Later, it was observed a significant increase of trapped holes able to carry out the direct photocatalytic oxidation of aqueous orange G (without electron scavenger’s assistance, e.g. gaseous O2). On the other hand, the photogeneration of oxidant •OH radicals decreased dramatically while H increased [6].[1] Y. Bian et al., RCS Adv., 11(2021)6284.; [2] D. Kim et al., J. Phys.: Condens. Matter,21(2009)195405.; [3] B. Shao et al., J. Appl. Phys.,115(2014)17A915. [4] N. Kopidakis et al., J. Phys. Chem. B, 107(2003)11307. [5] J. van de Lagemaat et al., J. Phys. Chem. B,104(2000)4292. [6] K.-I Ishibashi et al., J.Photochem.Photobiol.A,134(2000)139-142. Acknowledgements The authors thank the National Council for Science and Technology (CONACyT) Mexico for the funding support (grants CB No. 258789 and FOINS No. 3838). JIVN thanks CONACyT for his doctoral fellowship support (grant No. 893260).

Modulation of radical and nonradical pathways via modified carbon nanotubes toward efficient oxidation of binary pollutants in water

In order to minimize the knowledge gap between single and binary pollutants degradation by persulfate-based advanced oxidation processes (PS-AOPs), iron-loaded N-doped carbon nanotubes (Fe-NCNT) and its acid-washing sample (Fe-NCNT-W) were synthesized as peroxymonosulfate (PMS) activator for simultaneous oxidation of acid orange 7 (AO7) and electron-rich (phenol/ibuprofen) or electron-deficient pollutants (nitrobenzene/benzoic acid). Mechanistic studies revealed that both radical (HO•, SO4•−) and nonradical (electron-transfer, high-valent iron) pathways involved for organic oxidation in Fe-NCNT/PMS system, while electron-transfer pathway (ETP) and high-valent iron-oxo species accounted for pollutant degradation at the surface and inner space of Fe-NCNT-W, respectively. The oxidation performances in single or binary systems were systematically investigated. In comparison to benchmark radical-based (Fe2+/PMS), nonradical ETP (NCNT/PMS) and mixed (Fe-NCNT/PMS) systems, Fe-NCNT-W/PMS outperformed superior performance toward oxidation of binary pollutants with little inference from solution pH or background substances, which could also be fabricated into membrane reactor for actual dyeing sewage treatment. Such superiorities should be mainly ascribed to the particular selectivity and intensive treatment of nonradical pathways in Fe-NCNT-W/PMS system with nanoconfinement effect. This work affords novel insights into the treatment of combined pollution via PMS activation by engineered nanomaterials.

Development and Use of a Real‐time In‐situ Monitoring Tool for Electrochemical Advanced Oxidation Processes

AbstractAn apparatus for real‐time in‐situ monitoring of electrochemical advanced oxidation processes using visible spectrophotometry has been developed. Central to the design is a 3D‐printed sleeve that interfaces commercially available electrochemical and spectrophotometry units. Using the anodic oxidation of Acid Orange 7 as a test bed, the apparatus has been used for probing the impact of varying electrode composition, current density, electrolyte concentration, and stirring speed on the rate of decolorization. In addition, the unit was used to prove that decolorization can continue after electrolysis has been stopped, thereby showing the inherent value of real‐time monitoring. Given that a significant challenge in the field of advanced oxidation processes is the inability to compare different reported systems, our approach, using commercially available equipment and a printable interface may open avenues for more standardized data collection.

Photocatalytic Degradation of Textile Orange 16 Reactive Dye by ZnO Nanoparticles Synthesized via Green Route Using Punica Granatum Leaf Extract

Since it does not use any dangerous chemicals and is a simple, low-cost process, the green synthesis approach for nanoparticle creation has several benefits compared to the physical and chemical synthesis routes. The current study describes an environmentally friendly synthesis of zinc oxide (ZnO) nanoparticles (NPs) using an extract of Punica granatum plant leaves. Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible spectrophotometer (UV-Vis), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques were used to characterize the morphology, composition, and structural properties of the synthesized zinc oxide nanoparticles. The XRD pattern reveals that the ZnO nanoparticles are crystalline and have a diameter of 20 nm. According to the FESEM studies, the ZnO-NPs have sizes ranging from 50 to 100 nm on average and are almost spherical. When exposed to direct sunlight, the produced ZnO-NPs demonstrate impressive photocatalytic oxidation of textile Orange 16, a reactive dye. As a result, our research advances the development of a green photocatalyst for the removal of harmful dyes from water.

Hollow-structured Pd/TiO2 as a dual functional photocatalyst for methyl orange oxidation and selective reduction of nitrate into nitrogen

Nitrate pollution in wastewater has posed a threat to human health and the environment. Photocatalytic reduction is a promising technology to remove nitrate due to its high adaptability, low cost, and high efficiency. However, there is a great challenge to design photocatalyst with high nitrate reduction and high selectivity of nitrogen (N2) yield. In this study, a novel hollow-structured Pd/TiO2 (PHT1) photocatalyst is synthesized with large specific surface area (SBET) and pore volume, strong UV adsorption, high reduction potential than nitrate to nitrite, high charge transfer rate, and low electron-hole recombination rate. PHT1 exhibits a superior photocatalytic activity on the removal of methyl orange and nitrate. In addition, PHT1 exhibits high N2 selectivity (>95 %). A lower pH can promote the reduction of nitrate and the selectivity of N2 by PHT1. Electrons (e-) and CO2– are the main active species for nitrate reduction with OH as auxiliary radicals. Three main pathways for nitrate reduction are proposed: i) the reaction with formic acid under acidic conditions; ii) the reduction by electrons and the loaded Pd of photocatalyst to capture electrons to inhibit electron-hole recombination; iii) the reduction by CO2– generated from formic acid oxidation by OH.

Electrochemical Sensing Platform Based on Functionalized Multi-Walled Carbon Nanotubes and Metal Oxide for the Detection and Degradation Studies of Orange II Dye.

Textile industry effluents are heavily contaminated with dyes. The discharge of these toxic dyes into waterbodies poses a serious threat to aquatic flora and fauna. The ultimate entrance of these toxins from thereon into the food chain affects the primary and secondary consumers. Therefore, the adoption of a sustainable solution for protection against the detrimental effects associated with adulterated water is an immediate need of the hour. To address the severity of the issue, the present work aims to design an electrochemical sensing platform by modifying the glassy carbon electrode (GCE) with zinc oxide nanoparticles and amino group-functionalized multi-walled carbon nanotubes (NH2-fMWCNTs) for the detection of Orange II, which is a toxic azo dye. Zinc oxide nanoparticles facilitate electron transfer between the transducer and the analyte. While, the positively charged NH2-fMWCNTs in acidic medium help in preconcentration of negatively charged analyte molecules at the electrode/electrolyte interface. The modification of the GCE catalyzed the oxidation of Orange II, as evidenced by the negative shift of the oxidation potential and enhancement in peak current intensity. Square wave voltammetry was used to optimize various experimental conditions, such as the supporting electrolyte, pH of the electrolyte, deposition potential, and deposition time for the best performance of the designed sensor. Under the optimized conditions, the detection limit and quantification of the designed sensor were found to be 0.57 and 1.92 nM, respectively. The catalytic degradation studies of Orange II was shown to be facilitated by titanium dioxide, which acted as a photocatalyst. The addition of hydrogen peroxide further promoted the extent and rate of degradation of dye. The breakdown of Orange II was probed by the designed sensing platform electrochemically and also by UV–visible spectroscopy. The dye degraded up to 92% by following pseudo-first-order kinetics.

Electrochemical oxidation of acid orange 74 using Ru, IrO2, PbO2, and boron doped diamond anodes: Direct and indirect oxidation

• The BDD anode was most efficient in electrochemical oxidation of AO 74. • Mechanism of direct and indirect oxidation on different anodes were investigated. • Active radicals of indirect oxidation on PbO 2 and BDD anodes were examined. • The degradation pathways of AO 74 on different anodes were established. This study compares the electrochemical oxidation of acid orange 74 (AO 74), a typical metal complex azo dye, on four anode materials (Ru, IrO 2 , PbO 2 , and boron doped diamond (BDD)). The results show that the BDD electrode was quite efficient in the anodic oxidation of AO 74 with a 100% removal of AO 74 and an 84.3% removal of COD. Analyzing the active species at different electrodes, we reported that oxidation on an inert electrode primarily depends on direct oxidation and indirect oxidation of active radicals ( OH and O 2 − for the BDD anode and OH for the PbO 2 anode), whereas active electrodes (Ru and IrO 2 ) primarily depend on direct oxidation. The UV–vis spectrum demonstrated that Cr 3+ could be oxidized only on the BDD anode, proving that the BDD electrode has the highest oxidation potential. Similar organic intermediates species were observed on different electrodes by GC–MS. Furthermore, the different organic products are attributed to the difference in the oxidation ability of the electrodes. From the UV–vis spectrum and GC–MS analysis, we speculate that AO 74 was first degraded to aromatic compounds and pyrazole because of the cleavage of the azo-bond. Then it formed amides and organic acid because of the cleavage of the benzene ring, and finally CO 2 and H 2 O were formed.

Leaching of BPA from Baby Feeding Bottle, Aluminium Can and Thermal Printed Paper: Application of Acridine Orange Oxidation Inhibition Method to Estimate BPA

The potential of leaching Bisphenol-A (BPA) from plastic baby feeding bottles, aluminum cans, and thermal printed receipts was investigated under the aquatic condition at high temperatures. BPA is often used to manufacture cross-linked epoxy resin to coat food cans to prevent direct contact with metals and plastic materials. BPA leached from consumer product was analyzed using UV-Visible Spectrophotometer based on the inhibitory effect of BPA on acridine orange oxidation, as a function of change in temperature and time of contact of water with the samples. The proposed method of BPA estimation method was found to be significant and useful for aquatic conditions without any extraction and/or derivatization. The detection limit of BPA under the current experimental setup was 0.1 ng/ml. The results of BPA leached from baby feeding PET bottles, aluminum can with epoxy resin lining, and thermal paper were 87±10 ng/bottles, 68±5 ng/bottle, and 110±15 ng/receipt under the current experimental conditions.

Electrochemical properties of PrBaCo2O6 electrode in the oxidation of glucose and methyle orange

In this work, we investigate the possibility of using double cobaltite with the composition PrBaCo2O6 as an electrocatalyst in the oxidation of organic compounds. A screen-printed carbon electrode modified with the PrBaCo2O6 drop method was investigated as a sensor for glucose. The amperometric signal of this sensor is logarithmically dependent on the analyte concentration according to the equation: I (μA) = 9.485⋅ln(C (mM)) + 17.864 (R = 0.9951). The limit of detection is 0.52 μM (at S/N = 3). The linearity range is 0.0-17.5 mM, which corresponds to the physiological values of blood glucose concentration (3.3-5.5 mM). In addition, the possibility of electrooxidation of a refractory organic compound (methylene orange) using a modified electrode was shown.

A combined radical and non-radical oxidation processes for efficient degradation of Acid Orange 7 in the homogeneous Cu(II)/PMS system: important role of chloride.

Trace copper ion (Cu(II)) in water and wastewater can trigger peroxymonosulfate (PMS) activation to oxidize organic compounds, but it only works under alkaline conditions. In this work, we found that the presence of chloride could significantly accelerate the oxidation of Acid Orange 7 (AO7) by the Cu(II)/PMS process at a wide pH range (4.0-9.0). The observed pseudo-first-order rate constant k for AO7 oxidation was linearly correlated with the increased Cl- concentration (0-300 mM). An increase in mineralization rate was observed in the presence of Cl-, while the overall mineralization was quite low. Decomposition of PMS facilitated when Cl- concentration or pH value increased. Based on the scavenger experiments and electron paramagnetic resonance (EPR) measurement, the mechanism of Cu(II)-catalyzed PMS oxidation process in the presence of Cl- was proposed as both the radical and non-radical pathway, and 1O2 was the reactive oxygen species in the Cu(II)/PMS system. Finally, a possible degradation pathway of AO7 was elucidated. The feasibility of in situ utilizing high salinity and trace cupric species to accelerate the degradation of organic pollutants by the Cu(II)/PMS process in water and wastewater was demonstrated. However, the identification of undesired chlorinated by-products reminds us of cautiousness in assessing the application of Cu(II)/PMS system under chloride-rich environment. The findings of this work provide a simple and efficient approach to apply PMS in the remediation of refractory organic contaminants in the presence of trace cupric species under a high salinity environment with a wide range of pH.

Kinetics and mechanism of the oxidation of Orange II by periodate ion in aqueous acid

No Abstract.

Preparation and characterization of Cs1·48Sb0·78PMo11VO40. Application to the photo catalytic oxidation of orange II under solar light

Cs1·48Sb0·78PMo11VO40 (CsSbPMoV) was prepared and characterized by many physico-chemical techniques. The spectroscopies 31P MAS-NMR, FT-IR) and X-ray diffraction showed that the salt is pure, of Keggin-type crystallizing in a cubic structure.The UV–Vis spectrum revealed the presence of molybdenum and antimony with mixed valence states, Mo(VI)/Mo(V) and Sb(V)/Sb(III). The optical properties showed two transitions: directly (1.20eV) and indirectly (1.38eV) allowed. The intensity-potential (J- E), plotted in Na2SO4 (0.1 ​M), exhibited a sluggish electrochemical system. The capacitance−2– potential (C−2 - E) curve showed n-type behavior with a flat band potential (Efb) of 0.10 ​V and a conduction band positioned at 4.65 ​eV, below vacuum (−0.1 VSCE), composed mostly of (Mo, Sb) 5s wave functions, negative of the •OH/H2O level. Therefore, CsSbPMoV was successfully tested for theoxidation of Orange II (OII), a hazardous dye, by •OH and O2•radicals under solar light. The discoloration obeys a first order kinetic model with an abatement yield of 68% and a photo catalytic half-life (t1/2) of 60 ​min.

Mixed-valent manganese oxide for catalytic oxidation of Orange II by activation of persulfate: heterojunction dependence and mechanism

The coexistence of aliovalent cations in manganese oxide catalysts with a suitable mole ratio accelerates the activation process of persulfate for the degradation of organic pollutants.

Efficient silver nanocluster photocatalyst for simultaneous methyl orange/4-chlorophenol oxidation and Cr(VI) reduction

Metal nanoclusters have shown great potential in photocatalysis, while simultaneous removal of both inorganic and organic contaminants by metal nanoclusters under visible light is less explored. Here, we synthesized Agm(SR)n (SR represents 3-mercaptopropyltriethoxysilane ligand) nanoclusters (∼1 nm) via a reduction of silver triphenylphosphine under ambient conditions in the presence of 3-mercaptopropyltriethoxysilane. The nanocluster was characterized by UV–vis spectroscopy, high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectrum (FTIR), and X-ray photoelectron spectroscopy (XPS). Under 5 W blue LED, the Agm(SR)n/P25 exhibits enhanced catalytic activity for simultaneous methyl orange (MO) oxidation and Cr(VI) reduction, and also for synchronous 4-chlorophenol oxidation and Cr(VI) reduction. Mechanism studies by electrochemical impedance spectroscopy (EIS), photoluminescence (PL), electron spin resonance (ESR) etc. and control experiments reveal that the unique structure of silver nanoclusters with thiolate ligands is vital to the high catalytic performance, and both the photo-generated holes and superoxide radicals are responsible for the decomposition of MO.

Double Effects of Interfacial Ag Nanoparticles in a ZnO Multipod@Ag@Bi2S3 Z-Scheme Photocatalytic Redox System: Concurrent Tuning and Improving Charge-Transfer Efficiency.

Distinct functional materials in their combined form in a well-designed hybrid architecture offer great possibilities for creating a highly active photocatalytic system. Herein, a uniform multipod-shaped ZnO is synthesized through a natural template assisted route and progressively integrated with Ag nanoparticles (NPs) and Bi2S3 to form a three-component (3C) ternary photocatalytic system by a facile, two -step wet chemical approach. Encapsulation of polycrystalline Bi2S3 and assimilation of Ag NPs in between the interface of ZnO and Bi2S3 in the ternary hybrid are confirmed from electron microscopy and X-ray photoelectron spectroscopy, which resulted in improved UV-vis absorption, charge separation efficiency, and photocurrent response evaluated from optical absorption spectroscopy, photoluminescence, and photoelectrochemical cell measurements. This ternary hybrid shows high photoredox activity toward the hydrogen evaluation reaction (HER) (218.7 μmol h-1 g-1) and methyl orange (MO) oxidation (k = 3.21 × 10-2 min-1) compared to their binary and single counterparts. Moreover, on the basis of the estimation of the predominant active species (O2•-, •OH) in the photoredox catalysis and band edge positions from the Mott-Schottky plot, it was determined that both binary ZnO multipod@Bi2S3 and ternary ZnO multipod Ag@Bi2S3 hybrids undergo a Z-scheme electron transfer mechanism under irradiation of light. Here, the Ag ingredient in the ternary hybrids acts as an interfacial charge-transfer mediator to accelerate the Z-scheme electron transfer between Bi2S3 and ZnO along with plasmonic photosensitization to trigger the generation of plasmon-induced hot electrons. Such a cooperative concurrent dual role of Ag NPs in the Z-scheme ternary hybrid system considerably boosts the photoredox performance compared to direct Z-scheme binary hybrids. This work will enlighten and uncover the essential roles of metal NPs along with their cooperative synergy in Z-scheme photocatalytic systems as a prototypical example for substantial solar energy conversion.

Oxidation of azo dye Orange II with hydrogen peroxide catalyzed by 5,10,15,20-tetrakis[4-(diethylmethylammonio)phenyl]porphyrinato-cobalt(II)tetraiodide in aqueous solution

The catalytic oxidation of the azo dye Orange II by hydrogen peroxide in aqueous solution has been investigated using 5,10,15,20-tetrakis-[4-(diethylmethylammonio)phenyl]porphyrinato-cobalt(II) tetra iodide 1as catalyst. The oxidation reaction was followed by recording the UV–vis spectra of the reaction mixture with time at λmax = 485 nm. The factors that may influence the oxidation of Orange II, such as the effect of reaction temperature, concentration of catalyst, hydrogen peroxide and orange II have been studied. The results of total organic carbon analysis showed 52% of dye mineralization under mild reaction conditions. Residual organic compounds in the reaction mixture were identified by using Gas chromatography-mass spectrometry. The decolorization rate and mineralization of the dye has been found to increase with increase of catalyst concentration and reaction temperature. The rate of dye oxidation decreased with increasing the concentration of dye, H2O2 and at higher pH than 9. Radical scavenging measurement indicated that decolorization of Orange II by H2O2/cobalt (II) porphyrin complex 1 involved the formation of hydroxyl radicals as the active species.

B-site Substitution Effects on The Catalytic Activity of Perovskites Compounds towards Oxidative Degradation of Orange II Solutions

Perovskite is known as potential decent ceramic metal oxides catalyst for wastewater treatment particularly in catalytic oxidation process. Perovskites can be uniquely and chemically tailored due to its simple structure which able to accommodate wide range of A and/or B-site cations. In this work, detailed investigations on the substitution effect of different B-site cations into the main structure of perovskite compounds towards catalytic oxidation of orange II solution were performed. Four (4) different types of B-site metal cations (Cu, Ni, Mo and Co) were substituted into perovskites structure via a combined EDTA-citric acid complexation method. The reactivity of resultant perovskites was found to be in sequence of Na0.27Ca0.48Cu0.25O3 > Na0.25Ca0.48Ni0.27O3 ≍ Na0.09Ca0.29Mo0.62O3 > Na0.02Ca0.33Co0.39O3 in the absence of stimulant or oxidant during 2 hours heterogeneous reaction. Interestingly, Na0.09Ca0.29Mo0.62O3 perovskites catalyst exhibited superior catalytic activity by having complete Orange II removal (≍99%) in the presence of oxidant (0.022M H2O2) within 15 min of reaction. The reactivity of B-site perovskites catalysts changed significantly in presence of oxidant during heterogeneous reaction that can be represented as Na0.09Ca0.29Mo0.62O3> Na0.27Ca0.48Cu0.25O3>Na0.02Ca0.33Co0.39O3>Na0.25Ca0.48Ni0.27O, respectively. Such findings confer tunable and unique catalytic properties of B-site perovskites catalysts in enhancing the oxidative degradation of recalcitrant dye contaminated wastewater effluents.