Permanganate Research Articles

Insight into metal-free carbon catalysis in enhanced permanganate oxidation: Changeover from electron donor to electron mediator

Reports that the exploitation of metal-free carbon materials to enhance permanganate (PM) oxidation to abate organic pollution in water have emerged in recent publications. However, the activation mechanism and active sites involved are ambiguous because of the intricate physicochemical properties of carbon. In this study, reduced graphene oxide (rGO) as a typical carbon material exhibits excellent capability to boost permanganate oxidation for removing a wide array of organic contaminants. The simultaneous two reaction pathways in the rGO/PM system were justified: i) rGO donates to electrons to decompose PM and produce highly reactive intermediate Mn species for oxidizing organic contaminants; ii) rGO mediates electron transfer from organics to PM. Oxygen-containing groups (hydroxyl, carboxyl, and carbonyl) were justified as electron-donating groups, while structural defects (vacancy and edge defects) were shown to be critical for rGO-mediated electron transfer. Therefore, the oxidation pathway of the rGO/PM system can be controlled by regulating oxygen functional groups and structural defects. The changeover from electron donor to electron mediator by decorating surface active sites of carbon materials will be of great help to the design and application of carbocatalysts.

A Knitting Copolymerization Strategy to Build Porous Polytriazolium Salts for Removal of Anionic Dyes and MnO4.

Although considerable efforts have been devoted to novel ionic porous networks (IPNs), the development of them in a scalable manner to tackle the issues in pollutant treatment by adsorption remains an imminent challenge. Herein, inspired by natural spider webs, a knitting copolymerization strategy is proposed to construct analogue triazolium salt-based porous networks (IPN-CSUs). It is not only convenient to incorporate the cationic motifs into the network, but easy to control over the contents of ionic pairs. The as-prepared IPN-CSUs displays a high surface area of 924 m2 g-1 , a large pore volume of 1.27 cm3 g-1 and abundant ionic sites, thereby exhibiting fast adsorption rate and high adsorption capacity towards organic and inorganic pollutants. The kinetics and thermodynamics study reveal that the adsorption followed a pseudo-second-order kinetic model and Langmuir isotherm model correspondingly. Specifically, the maximum adsorption capacity of the IPN-CSUs is as high as 1.82mg mg- 1 for permanganate ions and up to 0.54mg mg-1 for methyl orange, which stands out among the previously reported porous adsorbents so far. It is expected that the strategy reported herein can be extended to the development of other potential efficient adsorbents in water purifications.

Mercapto-decorated Zn-based metal-organic framework embedded nanofibrous membrane for oxo-anions treatment in aqueous solution

Metal-organic frameworks (MOFs) and nanofibrous MOF-embedded membranes (NMOM) have drawn significant attention in recent times towards wastewater treatment. We report the fabrication of nanofibrous membrane (NMOM) embedded with a newly designed and developed Zn(II)-MOF {[Zn(L)(dmbpy)]n using ligands 1-(4-carboxyphenyl)-5-mercapto-1H-tetrazole (L) and 5,5′-dimethyl-2,2′-bipyridine (dmbpy)} bearing free mercapto and methyl groups on its surface. While the methyl group introduces hydrophobicity to the MOF, resulting in its good water stability, the free peripheral mercapto-functionality acts as interacting site for the foreign substrates. The NMOM was prepared by mixing Zn-MOF into a polyacrylonitrile (PAN) solution and extruding composite nanofibre via electrospinning technique. Both, Zn-MOF and Zn-MOF-based NMOM were used as selective adsorbents for the treatment of oxo-anion contaminated water. With these adsorbents, the selective adsorption, as well as separation of permanganate (MnO4−) ions from the mixture of permanganate (MnO4−) and dichromate (Cr2O72−), was achieved. The synthesized Zn-MOF was also utilized for the photocatalytic reduction of Cr(VI) to less toxic Cr(III) ions under UV light irradiation with good efficiency. The double faceted nature of Zn-MOF was further explored in a one-pot sequential selective adsorption of MnO4− ions from an aqueous mixture of both MnO4− and Cr2O72−, followed by photocatalytic reduction of Cr2O72− ions. Further, the developed NMOM was examined for a large-scale adsorption process. The pristine Zn-MOF showed a maximum adsorption capacity of 937.32 mg/g for the adsorption of MnO4− ions, whereas NMOM showed a higher adsorption capacity of 1077.56 mg/g. The enhanced hydrophobicity and surface area can be attributed to the increased adsorption capacity of the membrane. Thus, induced hydrophobicity of the membrane coupled with hydrolytic stable Zn-MOF showcases the potential of NMOM in treatment of oxo-anion contaminated wastewater.

Coupled adsorption-catalytic reduction of permanganate on Co–Al-layered double hydroxide for dye removal

Permanganate (MnO4−) ions were catalytically reduced to MnO2 by water molecules after adsorption on the surface of carbonate intercalated Co–Al-LDH. This reaction was very slow under experimental conditions in the absence of catalyst and was catalyzed by Co–Al-LDH and Co(II) ion had a key role in this process in the pH range of 2.8–13. But, at pH = 14, MnO4− ions reacted with Co(II) ion of adsorbent and produced Co(III). At all pHs, adsorption sites of Co–Al-LDH for MnO4− ions were Co–OH groups. These adsorption sites were located in micropores and mesopores of Co–Al-LDH and were called MI and ME adsorption sites, respectively. MnO4− ions were adsorbed on both adsorption sites in neutral aqueous solutions and only on ME sites at other pHs. Adsorption experiments were carried out at different temperatures, ionic strengths, pHs and initial adsorbate concentrations. Co–Al-LDH acted as a superadsorbent for MnO4− ions and maximum adsorption capacity was 347.9 mg g−1 (2.2 mmol g−1) in neutral aqueous solution at 318 K. The adsorption binding constants and thermodynamic parameters of adsorption of MnO4− ions on Co–Al-LDH were analyzed by ARIAN (adsorption isotherm regional analysis) model. This model determined the boundaries of adsorption of MnO4− ions on Co–Al-LDH under different conditions and showed that this process was endothermic in regions I and II of its isotherms in neutral solution and at pH = 13. This process obeyed ARIAN–Hinshelwood mechanism and water molecules in the pH range of 2.8–13 and hydroxide ions at pH = 14 participated as nucleophile reagents. Reaction in the pH range of 2.8–13 was as follows2MnO4−+ H2O →2MnO2(ad)+32O2+2OH− and at pH = 14 was as2MnO4−+2Co(II)–OH+H2O→2Co(III)–OH+2MnO2ad+32O2+2OH−This adsorbent was used for selective separation of permanganate from cationic safranin O and methylene blue dyes. However, it could not separate anionic methyl orange dye from MnO4− ions.This work further successfully demonstrated an approach to recycle the used Co–Al-LDH using a reducing agent.

Nitrosodiethylamine removal performance of modified activated carbon

Abstract This paper discusses the preparation of modified activated carbon (PAC-1) and its adsorption performance for nitrosodiethylamine (NDEA). The PAC-1 was characterized by SMS and X-ray diffractometer, and its NDEA removal mechanism was investigated. The results showed that, compared with unmodified activated carbon, PAC-1 had a better adsorption effect for NDEA after pre-soaking with 0.8 mol/L permanganate (PM) for 24 hours and calcination at 400 °C for 7 hours. Under the conditions of 8 g/L PAC-1 dosage, pH = 6, and adsorption time of 6 h, the adsorption rate of NDEA with an initial concentration of 50 mg/L reached 78.66%, the maximum equilibrium adsorption capacity was 4.916 mg·g−1, and the adsorption rate of unmodified activated carbon to NDEA was increased by 42.5%. The number of oxygen-containing surface functional groups of activated carbon was increased after permanganate prepreg, which can enhance the NDEA adsorption rate. The adsorption process of NDEA on modified activated carbon conforms to pseudo-second-order kinetics, and the adsorption isotherm corresponds to the Freundlich model.

Novel synthesis of antibacterial pyrone derivatives using kinetics and mechanism of oxidation of azithromycin by alkaline permanganate

Dimethylamino-2H-5-dihydropyrane-6-methyl-4-one (DADHP) is a novel antibacterial pyrones derivatives and potential pharmaceutical that was quantitatively synthesized by oxidizing azithromycin (AZ) antibiotic with potassium permanganate in an alkaline medium (pH > 12). The oxidation reaction was kinetically studied using spectrophotometric technique at ionic strength equal to 0.02 mol dm−3. The redox reaction was discovered to have two separate stages that could be measured. The first stage was relatively fast and corresponding to the formation of coordination intermediate complexes involving blue hypomanganate (V) and/or green manganate (VI) transient species. Variable parameters like as the concentration of permanganate ion and AZ substrate, as well as pH and ionic strength, have been studied to see how they affect oxidation rates. The experimental results showed a first-order dependency in [MnO4-] and fractional first-order kinetics in each of [AZ] and alkali concentration under pseudo-first-order reaction conditions of [AZ] ≫ 10 [MnO4-]. The oxidation process was base-catalyzed, and the oxidation rates increased as the alkali concentration increased. The product was confirmed by Fourier Transform Infrared spectroscopy (FTIR), elemental analysis, condensation tests with 2,4-dinitrophenyl haydrazine and hydroxyl amine, and GC-Mass. The oxidation product obtained can be employed as interesting class of organic compounds with diverse chemical and pharmacological applications.

Synthesis of nanocellulose aerogels and Cu-BTC/nanocellulose aerogel composites for adsorption of organic dyes and heavy metal ions

MOFs compounds with open metal sites, particularly Cu-BTC, have great potential for adsorption and catalysis applications. However, the powdery morphology limits their applications. One of the almost new ways to overcome this problem is to trap them in a standing and flexible aerogel matrix to form a hierarchical porous composite. In this work, Cu-BTC/CNC (crystalline nanocellulose) and Cu-BTC/NFC (nanofibrillated cellulose) aerogel composites were synthesized using a direct mixing method by the addition of Cu-BTC powder to the liquid precursor solution followed by gelation and freeze-drying. Also, pure nanocellulose aerogels (CNC and NFC aerogels) have been synthesized from cellulose isolated from peanut shells. Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra, and X-ray diffraction (XRD) were utilized to evaluate the structure and morphology of the prepared materials. The adsorption ability of pure CNC aerogel and Cu-BTC/NFC aerogel composite for organic dye (Congo Red) and heavy metal ion (Mn7+) was studied and determined by the UV–Vis spectrophotometry and inductively-coupled plasma optical emission spectrometry (ICP-OES), respectively. It was concluded that Cu-BTC/NFC aerogel composite shows excellent adsorption capacity for Congo Red. The adsorption process of this composite is better described by the pseudo-second-order kinetic model and Langmuir isotherm, with a maximum monolayer adsorption capacity of 39 mg/g for Congo Red. Nevertheless, CNC aerogel shows no adsorption for Congo Red. Both CNC aerogel and Cu-BTC/NFC aerogel composite act as a monolith standing solid reducer, which means they could remove permanganate ions from water by reducing it into manganese dioxide without releasing any secondary product in the solution.

Adsorption and reduction coupling of permanganate on MoS2: Water treatment and metal ion separation

Permanganate (MnO4−) ions were adsorbed on the surface of MoS2 nanosheet and then reacted with it. In this work, effects of pH, temperature, initial MnO4− concentration and ionic strength on this process were studied. The adsorption sites of MoS2 were Mo(IV)–S pairs located in its micropores (abbreviated as MI). Before starting reaction, MoS2 acted as a high capacity adsorbent for MnO4− ions at a certain time. Under various conditions, MnO4− ions were adsorbed on the surface of MoS2 during different time periods (20–180 ​min) and then reacted with it. The maximum adsorption capacity of MnO4− ions on MoS2 surface in water at 328 ​K was 368.3 ​mg ​g-1 (2.33 ​mmol ​g-1).Adsorption isotherms were analyzed by the ARIAN model and it was recognized that in the pH range of 1–11, adsorption isotherms were composed from regions I and II and ΔH values of the process for regions I and II in neutral water were 31.4 ​kJ ​mol-1 and 9.9 ​kJ ​mol-1, respectively. At pH ​= ​12, adsorption isotherm was only formed from region I. In the pH range of 1–12, after completion of adsorption process, reaction of adsorbed MnO4− ions with adsorbent obeyed ARIAN–Hinshelwood mechanism. In the pH range of 1–11, water molecules and at pH ​= ​12, OH− ions and water molecules acted as nucleophiles, respectively. Finally, MoS2 adsorbent was used for separation of Cr2O72− and Ni2+ ions from MnO4− ions in water.

Innovative approach for the synthesis of graphene/MnO2 nanocomposites and their electrochemical behavior

AbstractGraphene‐manganese dioxide composites were prepared using a simple one step method consisting of the electrochemical exfoliation of graphite in the presence of KMnO4 in 0.1 м H2SO4 at low temperature. In these conditions, the freshly exfoliated graphene sheets (EG) spontaneously reduce the permanganate ions and EG sheets decorated with MnO2 nanoparticles are obtained. This was confirmed by scanning electron microscopy coupled with energy dispersive X‐ray spectroscopy, transmission electron microscopy, X‐ray diffraction, Raman, and X‐ray photoelectron spectroscopies and thermogravimetric analysis. The electrochemical properties of EG@MnO2 material were investigated and discussed. Electrodes based on the composite material exhibited enhanced capacitive performances compared to those made from pure graphene sheets. This was attributed to the synergic effect between the two components (graphene sheets and manganese dioxide nanoparticles) and to a larger porosity of the EG@MnO2 electrode compared to the EG electrode. Additionally, over 91.6% of original capacitance was retained after 4000 cycles, indicating a very good cycling capability of the composite material. Remarkably, the composite electrode showed promising properties in aqueous medium by exhibiting a large and stable operating voltage up 2 V. The results presented in this article could serve as a guide for improving the energy density of supercapacitors in aqueous media.

Recyclable Functionalized Material for Sensitive Detection and Exceptional Sorption of Hexavalent Chromium and Permanganate Ions with Biosensing Applications.

Environmental remediation with a single platform for selective sensing and removal of toxic analytes with recyclability of the material has always been a desirable system for sustainability. However, materials comprising all the abovementioned advantages are rarely known for oxoanions. We herein developed a fluorogenic napthalimide-based functionalized mesoporous silica material (SiO2@NBDBIA) as a signaling and remediation system for oxoanions (CrO42-, Cr2O72-, and MnO4-) from a pool of several anions. The fluorescence quenching of the SiO2@NBDBIA material in the presence of CrO42-, Cr2O72-, and MnO4- ions gives the limit of detection (LOD) values of 6.23, 25.2, and 20.32 ppb, respectively, which are well below the maximum contaminant level demarcated by the United States Environmental Protection Agency. The maximum adsorption capacities of the material for the abovementioned oxoanions are found to be 352, 363, and 330 mg/g, respectively, which are well above those mentioned in the literature reports. Contrary to the literature-dominated irreversible ion-exchange mechanism, the reversible hydrogen-bonded binding of the material with the oxoanions leads to the recyclability of the material easily, which is very rare in the literature. The DFT calculations were performed to examine the interactions between the material and oxoanions. For real applications, this material was also used as a fluorescence probe to detect these oxoanions in the actual water samples, and more interestingly, used as a biosensing probe for these oxoanions in the living organism Artemia salina through fluorescence imaging. Thus, the SiO2@NBDBIA material is a unique example of recyclable material for detecting and remediating oxoanions.

Wastewater Purification from Permanganate Ions by Sorption on the Ocimum basilicum Leaves Powder Modified by Zinc Chloride

The powder of Ocimum Basilicum leaves was treated by zinc chloride (ZnCl2) and applied as a new and low-cost sorbent for extraction of permanganate anions (MnO4−) from liquid phase. The functional groups of the ring stretching vibration, –NH2 deformation, stretching of C-O, stretching of CH, and stretching of –NH were found in the sorbent of zinc chloride Ocimum basilicum leaves powder (ZCOBLP) at 1516.21, 1629.33, 1047.00, 2929.88, and 3294.93 cm−1, respectively. This adsorbent has 8.3 pHZPC, 117.27 m2·g−1 surface area, 0.00711 cc·g−1 pore volume and average pore diameter of 264.144 Å. The outcomes of sorption experiments designate the positive impact for temperature, time of agitation, and started concentration of MnO4− and negative impact for pH. The optimal conditions were 1300 mg·L−1 as started adsorbate concentration, 55°C as solution temperature, agitation time of 420 min, and pH of 1.5. The outcomes of the equilibrium and dynamic approve that this sorption is spontaneous and heat-absorbing process, and the obtained data were described well by isotherm model of Langmuir and 2nd-order dynamic model. The capacities of this sorption were 588.235, 625.000, 666.667, and 714.286 mg·g−1 at 25, 35, 45, and 55 (°C), respectively. The superior sorption capacities of the uncostly ZCOBLP will make it successfully used for MnO4− ions extraction from liquid phases.

Evaluation of Corrosion Inhibition of 316L Stainless Steel by Permanganate Ions in Chloride Solution

The efficiency of permanganates to inhibit the scale deposit captured the attention for more investigation on their role as corrosion inhibitor. In this article, the effect of permanganate as corrosion inhibitor on 316L stainless steel in NaCl solution is investigated. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) have been performed by varying the electrode stirring speed, the concentration of permanganate ions, pH and the temperature. The results show that the permanganate ions increase the cathodic and anodic currents under effect of stirring speed, due to oxygen reduction reaction and the reduction of permanganate ions. Electrochemical results indicate that the deposit of manganese oxide (MnO2) inhibits the pitting corrosion. The inhibition efficiency is up to 98 % for 10−4 mol.dm−3 of permanganate. The temperature reduces the effectiveness of permanganates against pitting corrosion, the pitting potential shifts cathodically from +0.395 V vs. Saturated Calomel Electrode (SCE) at 298 K to +0.275 V vs. SCE at 343 K. Surface morphology of the deposit oxide films and electrode are studied by emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared and Differential Scanning Calorimetry. The analysis of the deposit layer by X-ray diffraction revealed the presence of δ-MnO2 form, with a crystallite size of 3.17 nm. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Synthesis of Oxalic from Sugarcane Molasses by Oxidation-reduction Reactions using Permanganate Ion as Oxidant

Synthesis of Oxalic from Sugarcane Molasses by Oxidation-reduction Reactions using Permanganate Ion as Oxidant

Base-catalyzed oxidation of poly (ethylene glycol) by alkaline permanganate: Part I. Kinetics and mechanism of formation of coordination intermediate complex

A spectrophotometric investigation has been applied to study the kinetics of oxidation of poly (ethylene glycol) (PEG) as a synthetic polymer by alkaline permanganate at a constant ionic strength of 1.0 mol.dm−3. The reaction was found to proceed through two distinct measurable stages. The first stage was relatively fast and corresponding to the formation of coordination polymer intermediate complexes involving blue hypomanganate (V) and/or green manganate (VI) transient species. The influence of variable factors on the oxidation rates such as the concentration of permanganate ion and PEG substrate concentrations as well as the pH and ionic strength have been examined. Under the pseudo-first-order reaction conditions of [PEG] ≫ [MnO4−], the experimental results showed a first-order dependence in [MnO4−] and fractional first-order kinetics in each of [PEG] and alkali concentration. The oxidation process was of base-catalyzed nature where the oxidation rates were increased with increasing the alkali concentration. The observed first-order rate constant was found to be 1.1 ×10−3 s−1 with deprotonation constant of 0.72 dm3 mol−1 at 45 °C. Blue hypomanganate (V) was detected for the first time by using a conventional spectrophotometer. The oxidation process has proceeded without the intervention of a free-radical mechanism. Colloidal manganese (IV) and the acid derivatives of PEG were identified as final oxidation products. The activation parameters of the second-order reaction have been calculated and found to be ΔH≠ = 40.66 kJmol−1; ΔS≠ = − 145.41 Jmol−K−1 and ΔG≠ = 83.99 kJmol−1. A plausible reaction mechanism for oxidation based on the evaluated activation parameters and in good consistent with the observed kinetic data was suggested and discussed.

Exchange interactions in hexagonal YMnO3 and LuMnO3 multiferroic compounds

In this work, spin density functional theory calculations are employed to obtain the exchange interactions in hexagonal YMnO3 and LuMnO3 multiferroic compounds, which have been a matter of debate in the literature. The exchange and correlation electronic effects are approximated using the local spin density approximation (LSDA) with the inclusion of the effective Hubbard U correction (Ueff). The intraplane superexchange interaction (Jnn) decreases with increasing Ueff. Moreover, the Jnn value with the best agreement with experiment is found for Ueff values between 2.55 and 4.0 ​eV. Without the addition of Ueff corrections, i.e., with standard LSDA calculations, the magnitude of Jnn is overestimated. The Bader topological analysis of the electron density at the bond critical point shows that the closed-shell interaction of the Mn–O3 and Mn–O4 bonds in both materials increases with increasing Ueff, which justifies the decrease of Jnn with increasing Ueff.. Additionally, both interplane and intraplane super-superexchange interactions are computed and compared with previous studies.

Solid-Phase Quasi-Intramolecular Redox Reaction of [Ag(NH3)2]MnO4: An Easy Way to Prepare Pure AgMnO2.

Two monoclinic polymorphs of [Ag(NH3)2]MnO4 containing a unique coordination mode of permanganate ions were prepared, and the high-temperature polymorph was used as a precursor to synthesize pure AgMnO2. The hydrogen bonds between the permanganate ions and the hydrogen atoms of ammonia were detected by IR spectroscopy and single-crystal X-ray diffraction. Under thermal decomposition, these hydrogen bonds induced a solid-phase quasi-intramolecular redox reaction between the [Ag(NH3)2]+ cation and MnO4– anion even before losing the ammonia ligand or permanganate oxygen atom. The polymorphs decomposed into finely dispersed elementary silver, amorphous MnOx compounds, and H2O, N2 and NO gases. Annealing the primary decomposition product at 573 K, the metallic silver reacted with the manganese oxides and resulted in the formation of amorphous silver manganese oxides, which started to crystallize only at 773 K and completely transformed into AgMnO2 at 873 K.

Adsorptive removal of permanganate anions from synthetic wastewater using copper sulfide nanoparticles

The performance of Copper Sulfide (CuS) was evaluated as sorbent material for Permanganate ions (). The influences of pH, concentration, sorption time and temperature were inspected. The outcomes of this study approved that the sorbate primary concentration of 1200 mg l−1, solution pH of 1.5, 90 min sorption time and temperature of 60 °C are the optimal conditions for sorption by CuS. The study also revealed that the kinetic model of second order and model of Langmuir isotherm describe well the experimental data of this sorption. Furthermore, significant sorption capacities of 769.23, 909.09, 1111.11 and 1250.00 mg g−1 were resulted at 20 °C, 30 °C, 40 °C and 60 °C, one-to-one. Additionally, thermodynamic outcomes confirmed that the nature of sorption by CuS is a heat-absorbing and spontaneous.

Catalyst-free activation of permanganate under visible light irradiation for sulfamethazine degradation: Experiments and theoretical calculation

In this study, visible light (VL) was adopted for permanganate (PM) activation without additional catalyst, where sulfamethazine (SMT) was selected as the probe compound. Experiment results showed that the VL/PM system can effectively degrade SMT through pseudo-first-order reaction kinetics. Influencing factors including PM dosage, solution pH, humid acid (HA) and coexisting anions (CO32−, SO42−, Cl− and NO3−) which affect SMT photo-degradation were also examined. Pyrophosphate (PP) had an inhibitory effect on SMT degradation due to the complexation of PP with Mn (III). Electron spin resonance (ESR) spectrometry and UV-Vis spectrophotometer proved that VL can activate PM to generate ·O2− and Mn (III) reactive species. Furthermore, based on the active site prediction, intermediates identification and Density Functional Theory (DFT) calculation, two main degradation pathways involving SMT molecular rearrangement and cleavage of S–N bond were proposed. Moreover, the energy barriers of the two degradation pathways were also calculated. This study offers a novel approach for aqueous SMT removal and deepens our understanding of the degradation mechanism of SMT through DFT calculation, which hopes to shed light on the future development of VL/PM treatment.

New Nickel–Cobalt–Manganese Spinels

Three types of solid solutions of new nickel–cobalt–manganese spinels were synthesized by substitution for manganese cations in oxide Mn3O4: Ni(1 – x)Mn(2 + x)O4, Ni(1 – x)Co(1 – x)Mn(1 + 2x)O4, and Ni(1 – 2x)Co(0.5 – x)Mn(1.5 + 3x)О4. Complex oxides have been produced by solution combustion synthesis. The produced spinels expand the range of materials suitable for using as anodes of lithium-ion batteries.

Micellar and Polymer Catalysis in the Kinetics of Oxidation of L-lysine by Permanganate Ion in Perchloric Acid Medium

ABSTRACT Kinetics of oxidation of L-lysine by permanganate ion in a perchloric acid medium was investigated to explore the order of the reaction with respect to oxidant and substrate and to study the catalytic behaviour of sodium lauryl sulphate (SLS) and polyethylene glycol (PEG). The reaction was found to be first-order with respect to the oxidant and the substrate and zero-order with respect to hydrogen ion. Changes in the sodium sulphate concentration produce a non-significant variation in the rate of the reaction. SLS and PEG were found to catalyze the reaction. Surfactant catalysis was modelled by Piszkiewicz's cooperativity model, while polymer catalysis was explained with the help of the Benesi-Hildebrand equation. The temperature dependence of the rate of the reaction was elucidated, and activation parameters were obtained. Interestingly, the reaction was found to possess positive activation entropy indicating the dissociative nature of the transition state and outer-sphere electron transfer mechanism. A mechanism of the reaction that is supported by the experimental findings was suggested. Keywords: L-lysine, permanganate ion, micellar catalysis, polymer catalysis, outer sphere electron transfer mechanism.