potassium-permanganate and manganese-dioxide

Topics: Adsorption; Lignin; Manganese Compounds; Nanoparticles; Oxides; Potassium Permanganate; Water

Due to their cost effectiveness, high safety, and eco-friendliness, zinc-ion batteries (ZIBs) are receiving much attention nowadays. In the production of rechargeable ZIBs, the cathode plays an important role. Manganese oxide (MnO

Topics: Electrochemical Techniques; Electrodes; Manganese Compounds; Nanotubes, Carbon; Oxides; Potassium Permanganate

2-Methylisoborneol (2-MIB) is one of the most commonly observed taste and odor (T&O) compounds present in drinking water sources. As it is biodegradable, a preservation agent, typically mercury chloride, is needed if the water is not analyzed right after sampling. Since mercury is a toxic metal, an alternative chemical that is cheaper and less toxic is desirable. In this study, two chemicals commonly used in water treatment processes, chlorine (as sodium hypochlorite) and KMnO₄ (potassium permanganate), are studied to determine their feasibility as preservation agents for 2-MIB in water. Preservation experiments were first conducted in deionized water spiked with 2-MIB and with chlorine or permanganate at 4 and 25 °C. The results indicate that 2-MIB concentrations in the water samples spiked with both chemicals remained almost constant within 14 days for all the tested conditions, suggesting that oxidation and volatilization did not cause the loss of 2-MIB in the system. The experiments were further conducted for three different reservoir water samples with 30⁻60 ng/L of indulgent 2-MIB. The experimental results demonstrated that preservation with permanganate may have underestimated the 2-MIB concentration in the samples as a result of the formation of manganese dioxide particles in natural water and adsorption of 2-MIB onto the particles. Chlorine was demonstrated to be a good preservation agent for all three tested natural waters since oxidation of 2-MIB was negligible and biodegradation was inhibited. When the residual chlorine concentrations were controlled to be higher than 0.5 mg/L on the final day (day 14) of the experiments, the concentration reduction of 2-MIB became lower than 13% at both of the tested temperatures. The results demonstrated that sodium hypochlorite can be used as an alternative preservation agent for 2-MIB in water before analysis.

Topics: Adsorption; Biodegradation, Environmental; Camphanes; Chlorine; Manganese Compounds; Oxidation-Reduction; Oxides; Potassium Permanganate; Volatilization; Water Pollutants, Chemical

Recent studies have shown that manganese dioxide (MnO2) can significantly accelerate the oxidation kinetics of phenolic compounds such as triclosan and chlorophenols by potassium permanganate (Mn(VII)) in slightly acidic solutions. However, the role of MnO2 (i.e., as an oxidant vs catalyst) is still unclear. In this work, it was demonstrated that Mn(VII) oxidized triclosan (i.e., trichloro-2-phenoxyphenol) and its analogue 2-phenoxyphenol, mainly generating ether bond cleavage products (i.e., 2,4-dichlorophenol and phenol, respectively), while MnO2 reacted with them producing appreciable dimers as well as hydroxylated and quinone-like products. Using these two phenoxyphenols as mechanistic probes, it was interestingly found that MnO2 formed in situ or prepared ex situ greatly accelerated the kinetics but negligibly affected the pathways of their oxidation by Mn(VII) at acidic pH 5. The yields (R) of indicative products 2,4-dichlorophenol and phenol from their respective probes (i.e., molar ratios of product formed to probe lost) under various experimental conditions were quantified. Comparable R values were obtained during the treatment by Mn(VII) in the absence vs presence of MnO2. Meanwhile, it was confirmed that MnO2 could accelerate the kinetics of Mn(VII) oxidation of refractory nitrophenols (i.e., 2-nitrophenol and 4-nitrophenol), which otherwise showed negligible reactivity toward Mn(VII) and MnO2 individually, and the effect of MnO2 was strongly dependent upon its concentration as well as solution pH. These results clearly rule out the role of MnO2 as a mild co-oxidant and suggest a potential catalytic effect on Mn(VII) oxidation of phenolic compounds regardless of their susceptibility to oxidation by MnO2.

Topics: Catalysis; Chlorophenols; Kinetics; Manganese Compounds; Nitrophenols; Organic Chemicals; Oxidants; Oxidation-Reduction; Oxides; Phenols; Potassium Permanganate; Triclosan; Water; Water Pollutants, Chemical

Microorganisms are one of the most attractive and simple sources for the synthesis of different types of metal nanoparticles. The synthesis of manganese dioxide nanoparticles (MnO2 NPs) by microorganisms from reducing potassium permanganate was investigated for the first time in the present study. The microbial supernatants of the bacterium Saccharophagus degradans ATCC 43961 (Sde 2-40) and of the yeast Saccharomyces cerevisiae showed positive reactions to the synthesis of MnO2 NPs by displaying a change of color in the permanganate solution from purple to yellow. KMnO4-specific peaks also disappeared and MnO2-specific peaks emerged at an absorption maximum of 365 nm in UV-visible spectrophotometry. The washed Sde 2-40 cells did not show any ability to synthesize MnO2 NPs. The medium and medium constituents of Sde 2-40 showed similar positive reactions as supernatants, which indicate the role of the Sde 2-40 medium constituents in the synthesis of MnO2 NPs. This suggests that microorganisms without nanoparticle synthesis ability can be misreported for their abilities to synthesize nanoparticles. S. cerevisiae washed cells showed an ability to synthesize MnO2 NPs. The strategies of keeping yeast cells in tea bags and dialysis membranes showed positive tests for the synthesis of MnO2 NPs. A Fourier transform-infrared spectroscopy study suggested roles for the proteins, alcoholic compounds, and cell walls of S. cerevisiae cells in the synthesis of MnO2 NPs. Electron-dispersive X-ray spectroscopy analyses confirmed the presence of Mn and O in the sample. X-ray photoelectron spectroscopy revealed characteristic binding energies for MnO2 NPs. Transmission electron microscopy micrographs revealed the presence of uniformly dispersed hexagonal- and spherical-shaped particles with an average size of 34.4 nm. The synthesis approach using yeast is possible by a simple reaction at low temperature without any need for catalysts, templates, or expensive and precise equipment. Therefore, this study will be useful for the easy, cost-effective, reliable, and eco-friendly production of nanomaterials.

Topics: Culture Media; Filtration; Gammaproteobacteria; Manganese Compounds; Microscopy, Electron, Transmission; Nanoparticles; Oxides; Potassium Permanganate; Saccharomyces cerevisiae; Spectrum Analysis

The objective of this study was to develop a controlled-oxidant-release technology combining in situ chemical oxidation (ISCO) and permeable reactive barrier (PRB) concepts to remediate trichloroethene (TCE)-contaminated groundwater. In this study, a potassium permanganate (KMnO4)-releasing composite (PRC) was designed for KMnO4 release. The components of this PRC included polycaprolactone (PCL), KMnO4, and starch with a weight ratio of 1.14:2:0.96. Approximately 64% (w/w) of the KMnO4 was released from the PRC after 76 days of operation in a batch system. The results indicate that the released KMnO4 could oxidize TCE effectively. The results from a column study show that the KMnO4 released from 200 g of PRC could effectively remediate 101 pore volumes (PV) of TCE-contaminated groundwater (initial TCE concentration = 0.5 mg/L) and achieve up to 95% TCE removal. The effectiveness of the PRC system was verified by the following characteristics of the effluents collected after the PRC columns (barrier): (1) decreased TCE concentrations, (2) increased ORP and pH values, and (3) increased MnO2 and KMnO4 concentrations. The results of environmental scanning electron microscope (ESEM) analysis show that the PCL and starch completely filled up the pore spaces of the PRC, creating a composite with low porosity. Secondary micro-scale capillary permeability causes the KMnO4 release, mainly through a reaction-diffusion mechanism. The PRC developed could be used as an ISCO-based passive barrier system for plume control, and it has the potential to become a cost-effective alternative for the remediation of chlorinated solvent-contaminated groundwater.

Topics: Dichloroethylenes; Electric Conductivity; Groundwater; Hydrogen-Ion Concentration; Manganese Compounds; Microscopy, Electron, Scanning; Oxidation-Reduction; Oxides; Oxygen; Potassium Permanganate; Soil; Trichloroethylene; Vinyl Chloride; Waste Disposal, Fluid; Water Pollutants, Chemical

Cyanobacterial biomass shows high adsorption capacity toward heavy metal ions. However, the cyanotoxins in the cyanobacterial biomass inhibit its application in heavy metals removal. In order to safely and effectively remove Cd(II) from water using cyanobacterial bloom-derived biomass (CBDB), KMnO4 was used to modify CBDB. The results indicated that the microcystins in the CBDB were successfully removed by KMnO4. Potassium permanganate oxidation caused the transformation of hydroxyl to carboxyl on the CBDB, and formed manganese dioxide on the surface of CBDB. The oxidized CBDB showed higher adsorption capacity toward Cd(II) than that of unoxidized treatment. The optimal KMnO4 concentration for increasing the adsorption capacity of CBDB toward Cd(II) was 0.2g/L. The adsorption isotherm of Cd(II) by oxidized- or unoxidized-CBDB was well fitted by Langmuir model, indicating that the adsorption of Cd(II) by CBDB was monolayer adsorption. The desorption ratio of Cd(II) from oxidized CBDB was higher than that from unoxidized CBDB in the desorption process using NH4NO3 and EDTA as desorbent. The results presented in this study suggest that KMnO4 modified CBDB may be used as a safe and high efficient adsorbent in Cd(II) removal from water.

Topics: Adsorption; Biomass; Cadmium; Cyanobacteria; Eutrophication; Ions; Manganese Compounds; Metals, Heavy; Microcystins; Oxides; Oxygen; Potassium Permanganate; Water; Water Pollutants, Chemical; Water Purification

A laboratory-scale study with a sand column was designed to simulate trichloroethylene (TCE) pollution in the aquifer environment with three-section controlled-release potassium permanganate (CRP) barriers. The main objective of this study was to evaluate the feasibility of CRP barriers in remediation of TCE in aquifers in a long-term and controlled manner. CRP particles with a 1:3 molar ratio of KMnO4 to stearic acid showed the best controlled-release properties in pure water, and the theoretical release time was 138.5 days. The results of TCE removal in the test column indicated that complete removal efficiency of TCE in a sand column by three-section CRP barriers could be reached within 15 days. The molar ratio of KMnO4 to TCE in the three-section CRP barriers was 16:1, which was much lower than 82:1 as required when KMnO4 solution is used directly to achieve complete destruction of TCE. This result revealed that the efficiency of CRP for remediation of TCE was highly improved after encapsulation.

Topics: Environmental Restoration and Remediation; Groundwater; Manganese Compounds; Oxides; Potassium Permanganate; Stearic Acids; Trichloroethylene; Water Pollutants, Chemical

A new potassium permanganate reagent with slow-release properties was designed and tested for possible application in in situ chemical oxidation. For this purpose, MnO(2)-coated KMnO(4) particles (MCP) were prepared by partial reduction of solid KMnO(4) using the acid-catalyzed reaction with n-propanol or the comproportionation of Mn(VII) and Mn(II) in n-propanol as reaction medium. Column tests showed that, for MCP with a residual KMnO(4) fraction of 70wt%, the duration of permanganate release under flow-through conditions was prolonged by a factor of 10 compared to untreated KMnO(4). While KMnO(4) is too soluble to be used in reactive barriers, MCP could be introduced into the aquifer by filling of trenches or boreholes; this would allow a prolonged passive dosing of permanganate into the flowing groundwater. In addition, experiments were conducted in order to determine the oxidation capability of native KMnO(4) particles and MCP in CH(2)Cl(2), a representative non-polar non-aqueous phase liquid (NAPL). It may be possible to utilize the significantly higher reactivity of MCP under these conditions for the design of slow-release permanganate particles for NAPL source treatment.

Topics: Indicators and Reagents; Manganese Compounds; Microspheres; Oxidation-Reduction; Oxides; Potassium Permanganate

The reactions of permanganate ion with seven α-amino acids in aqueous KH(2)PO(4)/K(2)HPO(4) buffers have been followed spectrophotometrically at two different wavelengths: 526 nm (decay of MnO(4)(-)) and 418 nm (formation of colloidal MnO(2)). All of the reactions studied were autocatalyzed by colloidal MnO(2), with the contribution of the autocatalytic reaction pathway decreasing in the order glycine > l-threonine > l-alanine > l-glutamic acid > l-leucine > l-isoleucine > l-valine. The rate constants corresponding to the nonautocatalytic and autocatalytic pathways were obtained by means of either a differential rate law or an integrated one, the latter requiring the use of an iterative method for its implementation. The activation parameters for the two pathways were determined and analyzed to obtain statistically significant correlations for the series of reactions studied. The activation enthalpy of the nonautocatalytic pathway showed a strong, positive dependence on the standard Gibbs energy for the dissociation of the protonated amino group of the α-amino acid. Linear enthalpy-entropy correlations were found for both pathways, leading to isokinetic temperatures of 370 ± 21 K (nonautocatalytic) and 364 ± 28 K (autocatalytic). Mechanisms in agreement with the experimental data are proposed for the two reaction pathways.

Topics: Amino Acids; Buffers; Catalysis; Kinetics; Manganese Compounds; Oxidation-Reduction; Oxides; Potassium Permanganate; Spectrophotometry; Thermodynamics

This study investigated the process of potassium permanganate (KMnO(4)) oxidation and in situ formed hydrous manganese dioxides (deltaMnO(2)) (i.e., KMnO(4) oxidation and deltaMnO(2) adsorption) for the treatment of dye wastewater. The effectiveness of decolorization, removing dissolved organic carbon (DOC), and increasing biodegradable oxygen demand (BOD) were compared among these processes of KMnO(4) oxidation, deltaMnO(2) adsorption, and KMnO(4) oxidation and deltaMnO(2) adsorption. DeltaMnO(2) adsorption contributed to the maximum DOC removal of 65.0%, but exhibited limited capabilities of decolorizing and increasing biodegradability. KMnO(4) oxidation alone at pH 0.5 showed satisfactory decrease of UV-vis absorption peaks, and the maximum BOD(5)/DOC value of 1.67 was achieved. Unfortunately, the DOC removal was as low as 27.4%. Additionally, the great amount of acid for pH adjustment and the much too low pH levels limited its application in practice. KMnO(4) oxidation and deltaMnO(2) adsorption at pH 2.0 was the best strategy prior to biological process, in balancing the objectives of decolorization, DOC removal, and BOD increase. The optimum ratio of KMnO(4) dosage to X-GRL concentration (R(KMnO(4)/X-GRL)) was determined to be 2.5, at which KMnO(4) oxidation and deltaMnO(2) adsorption contributed to the maximal DOC removal of 53.4%. Additionally, the optimum pH for X-GRL treatment was observed to be near 3.0.

Topics: Adsorption; Coloring Agents; Manganese Compounds; Methylene Blue; Oxidation-Reduction; Oxides; Potassium Permanganate; Water Pollutants, Chemical; Water Purification

The aim of this study is to investigate the conditions for the removal of manganese ions from synthetic groundwater by oxidation using KMnO(4) to keep the concentration below the allowed level (0.05 mg/L). The process includes low-level aeration and addition of KMnO(4) in a Jar test system with Mn(2 + ) concentration of 0.50 mg/L, similar to that of natural groundwater in Taiwan. Different parameters such us aeration-pH, oxidant dose, and stirring speed were studied. Aeration alone was not sufficient to remove Mn(2 + ) ions completely even when the pH was increased. When a stoichiometric amount of KMnO(4) (0.96 mg/L) was used, a complete Mn(2 + ) removal was achieved within 15 min at an optimum pH of 8.0. As the amount of KMnO(4) was doubled, lower removal efficiency was obtained because the oxidant also generated manganese ions. The removal of Mn(2 + ) ions could be completed at pH 9.0 using an oxidant dose of 0.48 mg/L because Mn(2 + ) could be sorbed onto the MnO(2) particles. Finally, The MnO(2) particles were characterized using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX).

Topics: Cations, Divalent; Fresh Water; Hydrogen-Ion Concentration; Manganese; Manganese Compounds; Microscopy, Electron, Scanning; Models, Chemical; Oxidation-Reduction; Oxides; Potassium Permanganate; Surface Properties; Water Pollutants, Chemical; Water Purification

The effectiveness and mechanism of manganese dioxide (MnO2) enhancing permanganate (KMnO4) oxidation of phenolic compounds were investigated. Under the pseudo-first-order kinetic conditions (i. e., the initial concentration of KMnO4 was ten times higher than that of phenolic compounds), the oxidation kinetics of 2-chlorophenol and 4-chlorophenol by KMnO4 were examined. The reactions displayed autocatalysis, suggesting a catalytic role of in situ formed final products MnO2. Further experiments were conducted to evaluate the effects of the initial concentration and particle size of MnO2 additives as well as solution pH on KMnO4 oxidation. It was found that both ex situ-preformed colloidal and particulate MnO2 additives could significantly enhance KMnO4 oxidation of these phenolic compounds. Also, the pseudo-first-order rate constants K for the degradation of these phenolic compounds were observed to increase linearly with the increase of MnO2 concentration (in the range of 30 - 180 micromol x L(-1)). For the same concentration, colloidal MnO2 had much stronger ability than particulate MnO2 to promote KMnO4 oxidation. The increase of solution pH decreased the catalytic ability of MnO2. Moreover, it was found that MnO2 could catalyze KMnO4 oxidation of 2-nitrophenol which otherwise exhibited negligible reactivity toward MnO2 and KMnO4, respectively, but had no effect on KMnO4 oxidation of dimethyl sulfoxide (DMSO) which did not contain the moieties capable of forming complexes with the surface bound metals of MnO2. On the basis of these results, a catalytic mechanism was proposed; that was, the surface adsorption (i. e., the formation of surface complexes) was necessary and the surface bound phenolic compounds were more susceptible toward KMnO4 oxidation than their solution counterparts.

Topics: Adsorption; Biodegradation, Environmental; Catalysis; Chlorophenols; Manganese Compounds; Oxidation-Reduction; Oxides; Potassium Permanganate

In situ chemical oxidation (ISCO) is an emerging technology for the destruction of some chlorinated solvents present in subsurface environments. A laboratory investigation using a physical model was designed to assess the effectiveness of using permanganate as an oxidant to reduce the mass of a perchloroethylene (PCE) pool. The physical model was filled with silica sand overlying a silica flour base, simulating a two-dimensional saturated sand zone overlying a capillary barrier. PCE was introduced into the model so that it rested on top of the silica flour base, forming a dense nonaqueous phase liquid pool. The experimental methodology involved flushing the model with a permanganate solution for 146 days. During this period, measurements of chloride were used to assess the extent of pool oxidation. Before and after the oxidant flush, the quasi-steady state dissolution from the PCE pool was evaluated. Additionally, tracer studies were completed to assess changes in the flow field due to the oxidation process. At the termination of the experiment nine soil cores extracted from the model were used to detect the presence of MnO2 deposits and to quantify the mass of PCE remaining in the system. Excavation of the remaining material in the model revealed that the MnO2 distribution throughout the model was consistent with that observed in the cores. The oxidant flush was concluded before all of the pure phase PCE had been completely oxidized; however, approximately 45% of the PCE mass was removed, resulting in a fourfold decrease in the quasi-steady state aqueous phase mass loading of PCE from the pool. Measurements of chloride during the oxidant flush and of PCE in the soil cores suggested that the oxidation reaction occurred primarily at the upgradient edge of the PCE pool. MnO2 deposits within the model aquifer decreased the velocity of water directly above the pool, and the overall mass transfer from the remaining PCE pool. The results of this experimental study indicate that ISCO using permanganate is capable of removing substantial mass from a DNAPL pool; however, the performance of ISCO as a pool removal technology will be limited by the formation and precipitation of hydrous MnO2 that occurs during the oxidation process.

Topics: Chlorides; Manganese Compounds; Oxidation-Reduction; Oxides; Potassium Permanganate; Silicon Dioxide; Soil; Tetrachloroethylene; Water Pollutants, Chemical