Effects Of Various Inorganic Anions Research Articles

Efficient activation of peroxymonosulfate by Co-doped mesoporous CeO2 nanorods as a heterogeneous catalyst for phenol oxidation.

Sulfate radical-based advanced oxidation processes have received considerable attentions in the remediation of organic pollutants due to their high oxidation ability. In this study, a novel Co3O4/CeO2 catalyst was fabricated and employed as a peroxymonosulfate (PMS) activator to generate SO4•- for phenol degradation. The Co3O4/CeO2 catalyst exhibited a good catalytic performance at a wide pH range of 3.4 to 10.8, and 100% phenol (20 mg/L) was removed within 50-min reaction under optimal conditions with 0.2 g/L catalyst and 2.0 g/L PMS at room temperature. The transformation products and total organic carbon during the degradation process were also determined. The quenching experiments and electron paramagnetic resonance spectra revealed that sulfate radical (SO4•-) rather than other species such as singlet oxygen (1O2) and hydroxyl radical (•OH) was primarily responsible for phenol degradation in the Co3O4/CeO2/PMS system, and a rational mechanism was proposed. Moreover, the recycling experiments as well as low cobalt leaching concentration manifested satisfactory reusability and stability. The effects of various inorganic anions and natural organic matter in real water matrix on phenol oxidation were further evaluated. We believe that the Co3O4/CeO2 composites have promising applications of PMS activation for the degradation of organic pollutants in wastewater treatment.

The Kinetic Model for Decolorization of Commercial Reactive Red 120 Azo Dye Aqueous Solution by the Fenton Process and Study the Effect of Inorganic Salts

The degradation of a commercial azo dye Reactive Red 120 (RR120) in synthetic aqueous solution using Fenton's oxidation has been studied. The influence of different reaction parameters such as pH, hydrogen peroxide, ferrous sulfate, and the RR 120 concentration on the oxidative degradation of RR 120 have been appraised. The optimal reaction conditions were determined and it was found to be pH = 3.50, [H2O2] = 1.1×10-3 M, [Fe2+] = 1.0×10-4 M for [RR 120] = 7.5×10-5 M. Under optimal conditions, 96.0% decolorization efficiency of dye in aqueous solution was achieved after 15 min of reaction. The effect of azo bond loading (Lazo bond), from 0.25 to 1.0, and pH values from 2.5 to 5.0 were estimated on RR 120 color removal kinetic rates. A correlation between the kinetic of the color removal rates (ln k2) versus Lazo bond was carried out at the different pH levels. The color removal rate increased linearly with decreasing Lazo bond, in the order of pH: 3.5 > 5.0 > 2.5. All the experimental data were analyzed using the first and second-order kinetic models. The second-order provides the best correlation of the data. 67% Chemical Oxygen Demand (COD) removal efficiency of the RR 120 were achieved after 15 min of reaction by fixing the initial H2O2/Fe2+ molar ratio, COD loading factor (LCOD), and pH at 11, 0.25 and 3.5, respectively. Also, the effects of various inorganic anions (such as Cl−, SO42-, CO32-, etc.) on the oxidation efficiency of Fenton were studied. This study can benefit planners who deal with contaminated textile wastewater using chemical treatment by advanced oxidation technologies.

Photocatalytic activity of Pt–TiO2 films supported on hydroxylated fly ash cenospheres under visible light

TiO2 was coated on the surface of hydroxylated fly ash cenospheres (FACs) by the sol–gel method. Platinum (Pt) was then deposited on these TiO2/FAC particles by a photoreduction method to form PTF photocatalyst. The photocatalytic activity of PTF for the degradation of methylene blue (MB) under visible-light irradiation was determined. The PTF sample that was calcined at 450°C and had a Pt/TiO2 mass ratio of 1.5% exhibited the optimal photocatalytic activity for degradation of MB with a catalyst concentration of 3gL−1. MB was photodecomposed by PTF in aqueous solution more effectively at alkali pH than at acidic pH, because more MB molecules were adsorbed on the surface of PTF under alkaline conditions than that under acidic. The effect of various inorganic anions (HCO3−, F−, SO42−, NO3−, and Cl−) on the photodegradation of MB by PTF was also investigated. Addition of anions with a concentration of 5mM enhanced the photocatalytic efficiency of PTF because of the improved adsorption of MB. This effect weakened as the anion concentration was increased, which was attributed to the ability of the anions to scavenge hydroxyl radicals and holes. Our results indicated that the photodegradation of MB took place mainly on the catalyst surface. The generation of hydroxyl radicals in the photocatalytic reaction was measured by the fluorescence method. KI was used to determine the participation of holes in the photocatalytic reaction. Both hydroxyl radicals and valence-band holes were detected in the PTF system. Recycling tests revealed that calcination of the used PTF helped to regain its photocatalytic activity.

Degradation of carbamazepine by Fe(II)-activated persulfate process

Experimental studies were conducted to investigate the oxidative degradation of carbamazepine (CBZ), one of the most frequently detected pharmaceuticals in various waters, by Fe(II)-activated persulfate process. Results show that the Fe2+/S2O82− process is very effective for the elimination of CBZ and characterized by a two-stage kinetics (a rapid initial decay followed by a retardation stage). CBZ degradation reaction was observed to be pH dependent and the optimum pH is 3.0 in the range of 2.00–7.87. The concentration of Fe2+ and S2O82− exhibited a noticeable influence on CBZ removal efficiency, where [S2O82−] exerted more significant effects than that of [Fe2+]. The optimal molar ratio of CBZ, Fe2+, and S2O82− is found to be 1:5:40. The effect of various inorganic anions on CBZ removal was also evaluated under the optimal conditions. The anions NO3−, SO42− and H2PO4-caused a negative effect on the performance of this process, while Cl− interestingly accelerated CBZ degradation. The higher the Cl− concentration, the faster the CBZ decay rate. The intermediates were identified during CBZ degradation with and without the presence of Cl−. The evolution of intermediates for these two scenarios was compared. The decay pathways of CBZ were proposed accordingly.

Rapid decoloration of Reactive Black 5 by an advanced Fenton process in conjunction with ultrasound

The decoloration of reactive azo dye, Reactive Black 5 (RB5), by an advanced Fenton process in conjunction with ultrasound (Fenton/US) was investigated. The Fenton/US process using zero-valent iron (ZVI) aggregates as catalyst could achieve synergistic degradation of RB5, as compared to Fe(0)/US and Fenton systems. A synergy factor of 22.9 based on the first-order rate constant (k) was found. The decoloration efficiency was strongly influenced by initial pH, ZVI dose, H2O2 dose, ultrasonic input power, and the presence of salts in reaction solution. Experimental results showed that the optimum conditions for the decoloration of RB5 were ZVI 1g/L, initial pH 3.0, and H2O2 1.03×10−2mol/L with acoustic power of 120W/L at 60kHz. These conditions yielded 99% decoloration of 5.0×10−4M RB5 (ADMI 5605) solution within 10min treatment and the operation cost was only 2.25USD/m3. The dye solutions containing inorganic anions could retard the decoloration. The inhibitory effect of various inorganic anions on decoloration of RB5 followed the sequence of H2PO4-≫Cl->ClO4-≈NO3-≈SO42-. High acoustic power accelerated the reaction rate and increased decoloration efficiency. ZVI aggregates were reusable and the decoloration efficiency did not decrease substantially with repeated use of ZVI. Findings showed that the Fenton/US process could effectively decolor the reactive azo dye RB5 in wastewater.

Enhancement of Removal Rate of an Organic Pollutant in the Presence of Immobilized TiO2 Nanoparticles with Inorganic Anions Combination: Optimization Using Taguchi Approach

In this paper, the effect of various inorganic anions, NO3–, HCO3–, SO42–, Cl–, and H2PO4–, in the removal of C.I. Acid Red 17 (AR17), as a model dye pollutant, was investigated in the presence of TiO2 nanoparticles immobilized on a glass plate and optimized using the Taguchi method. Sixteen experiments were required to study the effects of anions in different concentrations. It was found that the nature and concentration of inorganic anions significantly affected the removal rate of AR17 in the presence of immobilized TiO2. The results indicated that high concentrations of NO3– and HCO3– especially in combined mode can improve the AR17 removal rate in the presence of supported TiO2. For the first time, we reported 22 times increase in the AR17 removal rate in the presence of immobilized TiO2 with combined inorganic anions. Among the mentioned anions, NO3– ions had the most contribution in increasing the removal rate and H2PO4– ions had the highest role in decreasing it. Results indicated that this method can be a useful, promising, and cost-effective method for increasing removal rate of organic pollutants in the fixed-bed system.

Effects of Inorganic Anions on TiO<sub>2</sub> Photocatalytic Reduction of BrO<sub>3</sub>

The effects of various inorganic anions (SO42−, NO3−, HCO3−/CO32−, Cl− and I−) on the photocatalytic reduction of BrO3- were investigated under UV light irradiation. The effects of the inorganic anions depend strongly on the property of radical scavenging and adsorption. At the concentration of 1.56 μmol/L, NO3−, SO42−, HCO3−/CO32−, Cl− and I− exhibit the property of radical scavenging and promote the reduction of bromate. At higher concentration than 1.56 μmol/L, NO3−, SO42−, and HCO3−/CO32− exhibit the property of adsorption and decrease the promotion of the reduction of bromate. Cl− has little effect on the reduction of bromate, it is due to the ability of the radical scavenging is lower than that of Br−. Only I− has a higher promotion of the reduction of bromate at higher concentration than 15. 64 μmol/L, it is due to the strongly reduction potential E0(•I/ I−).

Effect of inorganic anions on the photocatalytic decolorisation of an azo dye in the aqueous phase by cadmium sulphide/polymer nanocomposite films under visible light irradiation

Batch experiments were carried out to study the effects of various inorganic anions on the photocatalytic decolorisation of an azo dye (CI Methyl Orange 13025) in the aqueous phase in the presence of cadmium sulphide/polymer nanocomposite films under visible light irradiation. When anion concentrations were low (0.001 m), the inhibition effect on the photocatalytic decolorisation of CI Methyl Orange 13025 caused by these anions was ranked as . The presence of both and baffled the breakage of the benzene ring in the chemical structure of CI Methyl Orange 13025, while the presence of was of benefit to the degradation of the benzene ring. Adsorption experiments indicated that inorganic anions affected the decolorisation of CI Methyl Orange 13025 by competitive adsorption onto the surface of the photocatalyst. The photocatalytic decolorisation of CI Methyl Orange 13025 followed the pseudo‐first‐order kinetic reaction model well in all experimental cases.

Electrodeposition of monodispersed platinum nanoparticles on a glassy carbon electrode for sensing methanol

A facile, one-step and template-free method has been developed for the electrodeposition of well-dispersed platinum nanoparticles (Pt-NPs) on a glassy carbon electrode. The effects of various inorganic anions and overpotential on the morphologies and dimensions of the final products were investigated. The resulting Pt-NPs show high electrocatalytic activity towards methanol oxidation and are less easily poisoned by carbon monoxide.

Effect of various inorganic anions on the degradation of Congo Red, a di azo dye, by the photo-assisted Fenton process using zero-valent metallic iron as a catalyst

The present research focuses on the heterogeneous advanced photo-Fenton processes of the type Fe0/H2O2/UV and Fe0/ammonium persulfate (APS)/UV as a potential technique to degrade Congo Red (di azo dye). Both the oxidants H2O2 and APS showed comparable efficiencies on the iron surface for the mineralization of Congo Red (CR) under UV light. The influence of various reaction parameters like pH of the solution, catalyst loading, concentration of the oxidants (H2O2/APS), influence of hydroxyl radical scavenger and the concentration of the substrate dye molecules are investigated and the optimum conditions are reported. The influences of various inorganic anions that are commonly present in the industrial effluents are studied using the above processes. All the inorganic anions used shows inhibitive effect on the degradation rate. Inorganic anions like chloride (Cl-) and sulfate (SO2- 4) inhibit the degradation rate by forming complexes with Fe2+/Fe3+ ions in the solution and they also quench the generated hyd...

Degradation of azo dye Acid black 1 using low concentration iron of Fenton process facilitated by ultrasonic irradiation

A combination of ultrasonic and low concentration iron (<3 mgL −1) of Fenton process (US/Fenton) has been used to treat wastewater containing Acid black 1 (AB1). The results show that the oxidation power of low concentration iron of Fenton could be significantly enhanced by ultrasonic irradiation. The degradation of AB1 in aqueous solution by US/Fenton can receive better results compared with either Fenton oxidation or ultrasonic alone. Many operational parameters, such as ultrasonic power density, the pH value, the Fe 2+ dosage, the H 2O 2 dosage, AB1 concentration and the temperature, affecting the degradation efficiency were investigated. Also, the effects of various inorganic anions (such as Cl −, NO 3 - , CO 3 2 - , etc.) on the oxidation efficiency of US/Fenton were studied. Under the given test conditions, 98.83% degradation efficiency was achieved after 30 min reaction by US/Fenton. The effect of various inorganic anions was in the following decreasing order: SO 3 2 - > CH 3 COO - > Cl - > CO 3 2 - > HCO 3 - > SO 4 2 - > NO 3 - . The results show that the US/Fenton can be an effective technology for the treatment of organic dyes in wastewater.

UV or visible light induced photodegradation of AO7 on TiO 2 particles: the influence of inorganic anions

In this paper, the effects of various inorganic anions (NO 3 −, Cl −, SO 4 2−, HCO 3 −, H 2PO 4 −) on the photodegradation of an azo dye, acid orange 7 (AO7) were investigated under UV or visible light irradiation in the presence of TiO 2 particles. The effects of inorganic anions on the photodegradation of AO7 under visible light irradiation were significantly different from UV irradiation pathway. In TiO 2/UV system, inorganic anions inhibited the photodegradation of the dye by their trapping hydroxyl radicals. In TiO 2/Vis system, the observed inhibition effects of inorganic anions can be interpreted by competitive adsorption. In addition, the results indicated that the photodegradation of AO7 took place mainly in the bulk solution under UV light irradiation, while under visible light irradiation, the reaction occurred on the catalyst surface.

Multiphase Catalytic Hydrogenation of p-Chloroacetophenone and Acetophenone. A Kinetic Study of the Reaction Selectivity toward the Reduction of Different Functional Groups

A multiphase catalytic system consisting of hydrocarbon solvent and aqueous phase, phase-transfer (PT) agent (Aliquat 336), and supported Pt or Pd catalyst, bubbled with hydrogen at atmospheric pressure, affords the rapid and efficient hydrodechlorination and the selective reduction of the functional groups of p-chloroacetophenone and acetophenone at 50°C and in moderate reaction times. The reaction gives quantitative yields of reduction products with variable selectivity, which can be controlled by varying some simple reaction conditions. Herein both halogen removal and carbonyl group or phenyl ring reductions are discussed. The composition of the aqueous phase, the nature of supported catalysts, the effect of various inorganic anions, and other reaction conditions have been studied kinetically to estimate the mechanistic aspects of the reaction selectivity. Emphasis is placed on the development of a novel synthetic tool, which allows control over the selectivity in the reduction of the carbonyl group and the phenyl ring. A number of kinetic models and the corresponding integral rate expressions were used, coupled with the “simultaneous nonlinear least-squares fitting” method, to estimate the rate constants for the formation of each particular reaction component. The kinetic monitoring allowed the accurate analysis of the reaction selectivity. Some mechanistic conclusions were drawn for the reaction under study that suggest that “softer” reduction conditions are attained in the presence of a PT agent and the aqueous phase.

Effect of some inorganic anions on corrosion of tin in nitric acid solutions

AbstractThe electrochemical corrosion of tin in various concentrations of nitric acid has been studied. The change in corrosion rates with nitric acid concentration has revealed the occurrence of four distinct corrosion processes. The corrosion of tin was found to be maximum at 4·5M HNO3, and at 14·4M HNO3 the metal is passivated. The effect of various inorganic anions was investigated: it wasfound that some of these inhibit corrosion while others accelerate it. The anions added were NO2−, NO3−, Cl−, CrO42−, SO42−, S2O52−, HPO42−, H2PO−4, IO3−, and B4O72−. Of these, Cl− and CrO42− were studied in some detail. Acetate ions were also found to inhibit the corrosion of tin in nitric acid.

Physicochemical studies on dusts. IX. Analysis of silicious dusts: Effect of various inorganic ions on the determination of dissolved silica by the molybdenum‐blue method

AbstractThe effect of various inorganic anions and cations on the determination of silica by the molybdenum‐blue method is studied. The following ions do not interfere:Anions: Carbonate, chloride, nitrate, sulphate.Cations: Aluminium, calcium, magnesium, manganese.The extent and nature of the interference caused by the following ions is discussed:Anions: Dichromate, phosphate. Cations: Copper, ferrous iron, ferric iron.The effect of copper is noteworthy, in that compound formation is indicated, the apparent ratio of copper to silica in the complex being 12 : 1.