Potassium Permanganate Research Articles

Flow injection chemiluminescence determination of lambda-cyhalothrin and clodinafop-propargyl in freshwater samples

ABSTRACT A flow injection with chemiluminescence (CL) detection system applying tris-2,2′-bipyridylruthenium(II)–potassium permanganate ([Ru(bpy)3]2+–KMnO4) CL reaction was established to determine lambda-cyhalothrin (LCT) and clodinafop-propargyl (CP) pesticides in freshwater samples. Experimental parameters were optimised, and solid phase extraction was employed as phase separation techniques. Linearity of calibration curves for the standard solutions ranges of LCT and CP were of 0.001–1.0 mg/L (y = 1230.3x +23.895, R 2 = 0.9998 (n = 7)) and 0.001–2.0 mg/L (y = 680.12x +18.5, R 2 = 0.9998 (n = 9)), respectively. The respective limits of detection (LODs) and limits of quantification (LOQs) for LCT and CP were found as 3.4 × 10−4 and 3.5 × 10−4 mg/L (3σ blank) and 9.3 × 10−4 and 9.6 × 10−4 mg/L (10σ blank). The injection throughput was 115 h−1. As a consequence of applying tests of significance, the obtained results by the suggested method were not significantly different from those of the reported methods at a 95% confidence level. Recoveries for LCT and CP were achieved over the ranges of 93.8–108% (relative standard deviation (RSD) = 1.7–3.4%) and 93.4–108.2% (RSD = 2.2–3.5%), respectively. The most possible CL reaction mechanism was investigated and formulated.

Stability of the Glycated Amino Acid 6-(2-Formyl-5-hydroxymethyl-1-pyrrolyl)-l-norleucine (Pyrraline) During Oxidation.

Food proteins may be modified during processing and storage through reactions with reducing sugars (Maillard reaction, glycation) or by reactive oxygen species (protein oxidation). Little is known about particular reactions at the interface of glycation and oxidation. In the present study, the glycated amino acid pyrraline (6-(2-formyl-5-hydroxymethyl-1-pyrrolyl)-l-norleucine) and the proteinogenic amino acids tyrosine and tryptophan were subjected to different types of oxidation. The stability of the amino acids was assessed by HPLC with UV detection, whereas oxidation products were assigned by HPLC with triple quadrupole or time-of-flight mass spectrometric detection. Conditions that lead to oxidation of aromatic proteinogenic amino acids can also lead to oxidation of pyrraline. Pyrraline was particularly unstable in the presence of permanganate, hypochlorite, and under hydroxyl radical-generating conditions (iron, ethylenediaminetetraacetic acid, ascorbic acid). Evidence obtained by high-resolution mass spectrometry revealed the oxidation of pyrraline to 6-(2,5-diformyl-1-pyrrolyl)-l-norleucine, 6-(2-carboxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine, 6-(2-formyl-5-carboxy-1-pyrrolyl)-l-norleucine, and 6-(2,5-dicarboxy-1-pyrrolyl)-l-norleucine in the presence of potassium permanganate. The latter product was isolated by semipreparative HPLC and characterized by NMR. Under hydroxyl radical-generating conditions, pyrraline is hydroxylated at the ring under formation of 6-(2-formyl-4-hydroxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine or 6-(2-formyl-3-hydroxy-5-hydroxymethyl-1-pyrrolyl)-l-norleucine. This study shows that the so-called "advanced glycation end products" are no end products of the Maillard reaction, but may undergo further chemical degradation reactions.

Rapid and efficient removal of water-soluble dyes via natural asphalt oxide as a new carbonaceous super adsorbent; NA-oxide synthesis and characterization

In this study, natural asphalt was oxidized to synthesize a new nano-structure adsorbent for dye removal. The functionalization of natural asphalt by oxidation introduced new properties that influenced its activity. The process of oxidizing natural asphalt with potassium permanganate resulted in a low-cost adsorbent, which can potentially be a more affordable option compared with synthetic alternatives. Characterization analysis confirmed the enhanced surface area, improving dye interaction and adsorption. The interconnected channels and capillaries of the oxidized natural asphalt facilitated the capillary action drawing in liquids, including dyes. The distinctive porosity of natural asphalt oxide (NA-oxide) was noted, and the experimental results showed that the NA–oxide nanoadsorbent efficiently adsorbed cationic and anionic dyes in water, with maximum capacities of 14.68 mg.g−1, 17.81 mg.g−1 and 16.47 mg.g−1 for methyl orange, methylene blue and Rhodamine B, respectively. The study investigated various parameters, such as concentration, adsorption dose, pH, contact time, and temperature, affecting the dye removal process. Langmuir, Freundlich, and Temkin isotherms along with pseudo-first and pseudo-second-order kinetic equations were applied to assess the adsorption process, indicating that dyes adhered to the pseudo-first-order model and Langmuir isotherm. Analysis of MO, MB, and RhB dyes revealed conformity to Langmuir isotherm and first-order kinetics. Thermodynamic evaluations like ΔH°, ΔS°, and ∆G° displayed the exothermic and spontaneous nature of dye adsorption on the NA-oxide adsorbent. Furthermore, the absorbent displayed remarkable stability with a recovery rate of 98.45% after ten cycles, signifying its potential for enduring effectiveness in dye removal processes.

Production of Biopolymer & Preparation of Soap Using Chitin and Chitosan from Brachyura Shell

Collagen, an extracellular protein, was extracted from eggshells using a combination of 5% EDTA, 0.45 M NaCl, 0.2% NaOH, 0.2% H₂SO₄, 0.7% citric acid, and 10% HCl, while chitosan, a naturally occurring polysaccharide, was extracted from crab shells (Brachyura) through demineralization with 1N Hydrochloric acid, deproteinization using 6% sodium hydroxide solution, and deacetylation with 40% NaOH, followed by decolorization using potassium permanganate and oxalic acid. The proximate analysis of chitosan revealed an ash content of 32% and a moisture content of 4.13%, while the protein content of the extracted collagen was found to be 70 µg/dL, with an alternative method indicating 75 µg, equivalent to BSA. The molecular weights of collagen and chitosan were determined to be 300 kilodaltons and 190-310 kilodaltons, respectively, and their purity was confirmed using FTIR analysis. Hydrogels were prepared using a combination of collagen and chitosan and were tested for water absorption capacity and antimicrobial activity, demonstrating that both biomaterials possess significant antimicrobial and antioxidant properties. Additionally, chitosan’s biocompatibility supports its use in creating edible films that can interact with other biopolymers and additives, indicating its potential for various industrial and biomedical applications.

Manganese Oxide-Doped Hierarchical Porous Carbon Derived from Tea Leaf Waste for High-Performance Supercapacitors.

Hierarchical porous carbon derived from discarded biomass for energy storage materials has attracted increasing research attention due to its cost-effectiveness, ease of fabrication, environmental protection, and sustainability. Brewed tea leaves are rich in heteroatoms that are beneficial to capacitive energy storage behavior. Therefore, we synthesized high electrochemical performance carbon-based composites from Tie guan yin tea leaf waste using a facile procedure comprising hydrothermal, chemical activation, and calcination processes. In particular, potassium permanganate (KMnO4) was incorporated into the potassium hydroxide (KOH) activation agent; therefore, during the activation process, KOH continued to erode the biomass precursor, producing abundant pores, and KMnO4 synchronously underwent a redox reaction to form MnO nanoparticles and anchor on the porous carbon through chemical bonding. MnO nanoparticles provided additional pseudocapacitive charge storage capabilities through redox reactions. The results show that the amount of MnO produced is proportional to the amount of KMnO4 incorporated. However, the specific surface area of the composite material decreases with the incorporated amount of KMnO4 due to the accumulation and aggregation of MnO nanoparticles, thereby even blocking some micropores. Optimization of MnO nanocrystal loading can promote the crystallinity and graphitization degree of carbonaceous materials. The specimen prepared with a weight ratio of KMnO4 to hydrochar of 0.02 exhibited a high capacitance of 337 F/g, an increase of 70%, owing to the synergistic effect between the Tie guan yin tea leaf-derived activated carbon and MnO nanoparticles. With this facile preparation method and the resulting high electrochemical performance, the development of manganese oxide/carbon composites derived from tea leaf biomass is expected to become a promising candidate as an energy storage material for supercapacitors.

Operando Spectroelectrochemical Imaging of Concentration Fields and Tafel Kinetics in Microfluidic Electrochemical Devices.

With the development of microtechnologies for energy conversion and storage, mass transfer and micromolar concentration variations need to be measured at the microscale. These advances need to be accompanied by novel imaging techniques with the capability of achieving high spatial resolution while detecting very small signal variations (less than 0.1%). Thus, in this study, a new microscopy technique is proposed based on a combination of electrochemical impedance spectroscopy (EIS) and visible imaging spectroscopy to measure the concentration fields at the micromolar scale in operando microfluidic fuel cells (MFCs). This technique exploits EIS modulation and Fourier analysis to reduce the noise during concentration field imaging. A mass transfer model in the periodic regime is derived to validate the measurements and to estimate the Tafel kinetics and mass diffusivities during potassium permanganate reduction from only one potential measurement. The proposed imaging method and mathematical framework presented in this study can be used to study binary electrochemical reactions without gas production.

Engineered biochars for simultaneous immobilization of as and Cd in soil: Field evidence

Agricultural soil contamination by potentially toxic elements (PTEs) such as arsenic (As) and cadmium (Cd) poses a serious threat to food security. Immobilization serves as a widely used approach for the remediation of PTEs contaminated soils, nevertheless, the long-term effectiveness for the simultaneous immobilization of both cations and oxyanions remains a challenge. In order to effectively enhance the synergistic immobilization effect of soil As and Cd contaminated by multiple elements and improve the ecological environment of farmland. In this study, a typical polluted tailings area farmland was selected for situ immobilization experiments, and biochar was prepared from cow manure (CMB), rice straw (RSB), and pine wood (PWB) as raw materials. On this basis, the pristine biochar was modified with ferric chloride (F), potassium permanganate (K), magnesium chloride (M), and aluminum chloride (A), respectively. Furthermore, the immobilization effect of modified biochar on As-Cd and the stress effect on soil respiration were investigated. The results showed that CMB and RSB reduced the bioavailability of heavy metals, potassium permanganate has strong oxidizing properties, and the strong oxidability of potassium permanganate stimulated the generation of more oxygen-containing functional groups on the surface of biochar, thereby enhancing the adsorption and complexation effect of modified materials on As and Cd. Among them, the extracted Cd concentration of Diethylenetriamine pentaacetic acid (DTPA) in KCMB and KRSB in 2020 decreased by 8.23–43.12% and 9.67–35.29% compared to other treatments, respectively. Meanwhile, the KCMB and KRSB treatments also reduced the enrichment of As and Cd in plant tissues. In addition, the dissolved organic carbon (DOC) content in KCMB treatment was relatively high, and the carbon stability of the material was weakened. Simultaneously, the soil respiration emission of KCMB treatment was increased by 5.63% and 11.93% compared to KRSB and KPWB treatments, respectively. In addition, the structural equation also shows that DOC has a large positive effect on soil respiration. In summary, the KRSB treatment effectively achieve synergistic immobilization of As-Cd and provide important guiding significance for green and low-carbon remediation of polluted farmland.

Cardioprotective effect of lithium ascorbate in an in vivo model of myocardial infarction

The aim of the work was to study the cardioprotective effect of lithium ascorbate in an in vivo model of myocardial infarction. In the course of the study, we searched for compounds promising for therapy of acute myocardial infarction.Materials and methods. Myocardial infarction was modeled in Wistar rats by ligating the left coronary artery (the duration of ischemia was 45 minutes) followed by ligature loosening and 120-minute reperfusion. All manipulations were performed under alpha-chloralose anesthesia with mechanical lung ventilation and recording heart rate, blood pressure, and ECG. Lithium ascorbate was administered intravenously at a dose of 100 mg / ml before ischemia. The area at risk (the ischemia / reperfusion zone) was detected by staining the myocardium with tightened ligature with 5% potassium permanganate. After that consecutive myocardial slices were prepared, and infarct size was determined. Differentiation of the infarct size from the area at risk was performed by staining with 1% 2,3,5-triphenyl tetrazolium chloride solution for 30 minutes at 37 ºC. The infarct size and the area at risk were determined by the planimetric method. The serum concentration of myocardial damage marker creatine kinase-MB (CK-MB) was measured using ELISA kits.Results. Lithium ascorbate reduced the infarct size / area at risk ratio by 38% and decreased the serum CPKMB level in the experimental animals by 42% compared to the control group. Lithium ascorbate did not affect hemodynamics parameters during coronary artery occlusion and reperfusion.Conclusion. The cardioprotective effect of lithium ascorbate in cardiac ischemia / reperfusion in vivo was found.

Chemical characterization of hibiscus rosa-sinensis plant fibers facilitated through design of experiments and artificial neural network hybrid approach

The integration of natural fibers into Fiber Reinforced Polymers (FRPs) has emerged as a promising avenue for sustainable and high-performance composite materials. Natural fibers, derived from plants, offer notable advantages such as renewability, low cost, and environmental friendliness. Among these natural fibers, Hibiscus Rosa-Sinensis (HRS) plant fibers have gained significant attention owing to their widespread availability and unique mechanical properties. In this study, HRS fibers were chemically treated using Sodium Hydroxide (NaOH), Potassium Permanganate (KMnO4), and Acetic Acid (CH3COOH) at different weight percentages (3, 4, 5 Wt.%) and solutionizing times (1, 2, 3 h) based on Taguchi’s L27 orthogonal array. The fibers, extracted from epidermis of the stems, underwent cleaning and chemical treatment after water retting. The crystallinity index, determined via X-ray Diffraction (XRD), indicated a maximum value of 65.77%. Thermo-gravimetric analysis (TGA) exhibited a degradation temperature of 365.24 °C and a material loss of 63.11%. Potassium Permanganate treatment at 4 Wt.% and 3 h of solutionizing time has yielded the best results. Multi-Layer Perceptron Artificial Neural Network (MLP-ANN) has been successfully applied to accurately predict the output physical characteristics of chemically treated HRS fibers using experimental data. The results are in close alignment with the literature. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analyses have provided valuable insights into the microstructure and constituents of the chemically treated HRS fibers. This research emphasises on the effectiveness of the chemical treatment process in enhancing the properties of HRS plant fibers for potential composite applications.

Application of Different Staining Methods in the Diagnosis of Pigment-Rich Melanoma.

To compare the application of different treatments in the diagnosis of melanoma with severe pigment interference, to solve the problem of pigment interference with immunohistochemical interpretation. The pigment-rich melanomas were first depigmented with potassium permanganate using a concentration gradient (0.1%, 0.5%, 1%) and a time gradient (1, 5, 10, 15, 30 min, 6 h), and the optimal concentration and time were found. Then, 12 cases of pigment-rich melanoma tissues were collected, and the tissues were stained with diaminobenzidine (DAB), alkaline phosphatase-fast red (AP red), multiplex immunofluorescence (MIF), and 3-amino-9-ethylcarbazole (AEC), and ferrous sulfate, comparing different methods, positive expression of HMB45, MelanA, S100, SOX10, ki67. First, the concentration of 0.5% potassium permanganate after 15 min treatment of the pigment significantly faded, and the intensity of antibody positivity was better than other concentrations and time. Second, after depigmentation treatment, the antibody positivity rate was 41.7%-66.7% for DAB, 66.7%-91.7% for AP red, 83.3%-100% for multiplex immunofluorescence, 25%-33.3% for AEC, and 33.3% for ferrous sulfate. AP red staining and mIF are more suitable for the diagnosis of melanoma with severe pigment interference, and AP red staining is more economical and practical.

Biological Hazard Behind Lao Cuisine: Microbial Quantities and Efficacy of Difference Cleaning Detergents for Fresh Vegetables

This research aims to investigate the prevalence of bacterial hazards in fresh lettuce and peppermint sold in Nonkoh and Thatluang organic markets in Vientiane during dry and rainy seasons. Microbial counts were determined using Escherichia coli and Coliform plate count (3M PetrifilmTM) in two freshly consumed vegetables. To reduce microbial contamination, five different solutions were evaluated, including sodium chloride (NaCl) at 5 g/L (T1), viagra juice (CH3COOH) at 50 ml/L (T2), breaking soda (NaHCO3) at 5 g/L (T3), potassium permanganate (KMnO4) at 0.2 g/L (T4) and tap water is a control (T0). The results showed that the number of E.coli in lettuce was ranged from102 - 2 × 105 CFU/g and from 2 × 105 - 2 × 106 CFU/g in peppermint, exceeding the safety limit by Codex (<106 CFU/g). The coliforms counts were similar in both vegetables ranged from 2 × 105 - 2 × 106 CFU/g in lettuce and from 105 - 2 × 106 CFU/g in peppermint. During the dry season, E. coli was more prevalent in the Thatluang organic market (3.77 Log10 CFU/g) than in the Nonkoh market (2.33 Log10 CFU/g), but during the rainy season, both markets had similar results. The concentration of microbial contaminants in peppermint did not differ between the two seasons. In the cleaning experiment showed that T4 the most effective solution for reducing E. coli and Coliform levels, achieving reductions of 0.7-1.9 Log10 CFU/g (35.2-54.6%), and 2.0-2.2 Log10 CFU/g (33.6–39.1%), respectively. Therefore, a concentration of potassium permanganate (KMnO4) 50–100 mg/L (50-100 ppm) is recommended for vegetable cleaning purposed.

Continuous oxidation of organic contaminates in soil by polylactic acid-coated KMnO4

Potassium permanganate (KMnO4), as a versatile and safe solid source of MnO4-, received substantial attention from researchers as a potential soil oxidant reagent. In this study, we prepared polylactic acid (PLA)-coated KMnO4 (KMnO4@PLA) to control MnO4- release. The experimental results indicated that the optimal preparation scheme for KMnO4@PLA was a particle size of 1–2 mm, a solid-liquid ratio of 1:3, and a core-shell ratio of 1:3. And the release lifetimes of MnO4- from KMnO4@PLA in aqueous and quartz sand media were 200 hours and 310 hours, respectively, which were 2400 and 33 times longer than the release lifetimes of raw KMnO4. The controlled release of MnO4- from KMnO4@PLA was achieved through the hydrolysis of PLA. And the release process adhered to first-order reaction kinetics and displayed Fickian diffusion characteristics. Moreover, the removal of phenol by KMnO4@PLA in aqueous, quartz sand, and soil media were investigated through batch and flow column experiments. Compared with the raw KMnO4, the KMnO4@PLA exhibited a stronger ability to degrade phenol, due to the mildly acidic nature of the PLA shell. These findings demonstrated that KMnO4@PLA has significant advantages for the remediation of organically contaminated soils.

Role of quercetin in permanganate oxidation of bisphenol A: Kinetics and mechanism

Potassium permanganate (Mn (VII)) oxidation, a green advanced oxidation technology, is widely used as an in-situ remediation method for groundwater contamination. Based on the complexity of organic substances in aquatic environments, many novel organic components, whose processes and mechanisms affecting the oxidative efficacy of Mn (VII), remain unknown and need to be studied systematically. Therefore, using the reducing macromolecular quercetin as the organic matter, the efficiency and mechanism of quercetin-bound, low-valent Mn enhanced Mn (VII) oxidation of bisphenol A (BPA) were studied. The pH and concentration of quercetin strongly influenced its performance. Under pH 4.0–6.0, quercetin evidently promoted the BPA degradation rate in the Mn (VII)/quercetin (Mn (VII)/Q) system. However, the presence of quercetin had little effect on the degradation efficiency of Mn (VII) at pH ≥ 7.0. This study found that at pH 4.0–5.0, quercetin could act as both a reductant and complexing ligand in the process of BPA oxidation. As a complexing ligand, quercetin stabilized the intermediate states of Mn (III) to form complexes. These stable complexes could efficiently oxidize BPA. While low concentrations of quercetin were insufficient to complex and stabilize Mn (III), Mn (III) was reduced to Mn (II). Mn (II) then reacted with Mn (VII) to form MnO2, enhancing the degradation efficiency of the Mn (VII)/Q system for BPA through its catalytic and oxidative properties. This study provides a better understanding of the degradation of organic pollutants by KMnO4 in groundwater treatment.

Differences in soil biological activity and soil organic matter status only in the topsoil of Ferralsols under five land uses (Allada, Benin)

Land use change on the Ferralsols of the Allada Plateau in southern Benin has led to a slight decline in soil organic carbon (SOC) stocks over the last two decades. However, as in many African landscapes, detailed characterisation and quantified data on the SOC stocks and soil biological activity under major land uses are still poorly understood. The aim of this study was to characterise the biological activity and organic matter status of Ferralsols (0–30 cm) under the five major land uses on the Allada Plateau, i.e., forests, tree plantations, young and adult palm groves, and croplands (pineapple, maize). Soil biological activity was assessed using the standardised litter decomposition method (Tea bag index) and soil respiration (during a 28-day soil incubation). Soil organic matter status was characterised by quantifying SOC pools: soil microbial biomass carbon (MB-C), potassium permanganate oxidisable carbon (POX-C), and SOC associated to soil particle-size fractions (e.g. particulate organic matter, POM, and SOC associated to the clay soil fraction). The results indicated that SOC pools and biological activity were lower in tree plantations than in forests. The standardised litter decomposition was also slower in tree plantations than in forest. In croplands and palm groves, SOC pools and soil microbial biomass and respiration were lower than in forests and tree plantations. This high level of biological activity in forests, and at a lesser level in tree plantations, was effective in accumulating carbon in C pools associated to the clay fraction. Agricultural land uses, such as croplands and palm groves decreased all the soil C pools even those associated to the clay fraction, except for POX-C. However, these land-use effects on SOC pools decreased strongly with depth. At 10–30 cm, the differences in SOC pools or soil respiration between the five land uses were no more noticeable. Our results indicated that the amount of organic inputs was an essential factor to sustain high soil biological activity and SOC stabilisation in the clay size fraction, but only in the topsoil. Maintaining forests in the landscape is a priority in order to preserve SOC stocks and soil biological activity, which neither monospecific tree plantations nor cultivation can do at the same level.

An Oxygen‐Self‐Produced Nanoplatform Based on MnO2 for Relieving Hypoxia

Manganese dioxide ( MnO2) nanoparticles are increasingly recognized for their potential in biomedical applications, particularly in the realm of hypoxic cancer therapy, due to their unique physicochemical characteristics. This investigation introduces a novel, template‐free synthesis strategy. The reducing groups inherent in bovine serum albumin (BSA) facilitate a redox reaction with potassium permanganate (KMnO4), while the abundance of functional groups in BSA is instrumental in the formation of MnO2. The transmission electron microscopy (TEM) analysis has characterized the synthesized MnO2 nanoparticles, termed BM NPs, as spherical particles with a mean diameter of 210 nm and zeta potential of −40.1 mV measured by dynamic light scattering (DLS). The Fourier transform infrared (FT‐IR) spectrum of BM NPs exhibits the characteristic peak of MnO2 at 1113 cm‐1 and 620 cm‐1. Furthermore, the elemental composition of BM NPs has been ascertained through energy‐dispersive X‐ray (EDX) elemental mapping analysis. Though concentration of BM NPs up to 200 μg/mL, the survival rate of 4T1 cells remained approximately 75%. Given that BM NPs at a concentration of 100 µg/mL significantly alleviate cellular hypoxia, the high oxygen‐generating capacity of these nanoparticles is proved, suggesting their suitability as a drug delivery system, especially in the context of hypoxic tumor microenvironments.

Development of a smartphone-based colorimetric detection for quantification of vitamin C in dietary supplements and skin care products

This research project presents a development of an assay tool for quantification of vitamin C in dietary supplements and skin care products. The proposed method was developed based on decolorization of acidic potassium permanganate (KMnO4) by vitamin C through a redox reaction, with subsequent colorimetric detection by using digital imaging. The imaging was carried out using smartphone camera and free-downloaded RGB color detector application. To obtain optimal conditions, influential parameters such as light source position installed inside a 19 cm × 46 cm × 10 cm lightbox, reagent concentrations, and reaction time were studied. To the best conditions, good linearity (r2 > 0.99) in the range 1–70 mg vitamin C/L was obtained. Relative standard deviation was less than 3.9% indicating high precision. The proposed method was validated by quantification of vitamin C content in 15 sample solutions using the proposed method in comparison with the reference iodometric titration method. The results obtained from those two methods were not significantly different using paired t-test at confidence level of 95% (texp=0.41, tcrit=2.14). The results indicated that utilizing smartphone camera with free-downloaded color detector application is possible as an alternative analysis tool for determination of vitamin C.

8-Hydroxyquinoline incorporated ZIF-8 nanocomposites for efficient decomposition and detection of manganese ions in aquatic environments

The presence of potassium permanganate in aquatic environment poses a significant issue that requires resolution. In response, zeolitic imidazolate framework nanoparticles with large pore sizes, extensive surface areas, and high chemical stability in water were synthesized. Subsequently, 8-hydroxyquinoline was incorporated into ZIF-8 (named 8-HQ@ZIF-8) to enhance its capability to decompose potassium permanganate in aquatic environment. The synthesized material underwent thorough characterization using powder X-ray diffraction, Fourier-transform infrared spectroscopy, nitrogen isothermal adsorption-desorption at 77 K, thermogravimetric analysis, and scanning electron microscopy. Electrical conductivity tests revealed that the 8-HQ@ZIF-8 material can decompose potassium permanganate within 5 min and be recycled over five runs. Furthermore, the nanocomposite of 8-HQ and ZIF-8 exhibited greater stability than the original ZIF-8 under strong oxidizing conditions. This suggests that functionalizing with organic ligands can enhance the durability and performance of the material. In addition to its degradability, the 8-HQ@ZIF-8 material, which carries manganese oxide, also displays variable fluorescence properties, making it a potential sensor for detecting residual potassium permanganate in drinking water treatment systems. Therefore, the 8-HQ@ZIF-8 material shows considerable promise for both the treatment and detection of pollutants in aquatic environments.

In-situ manganese-aluminum-iron biochar derived from waste flocs for enhanced peroxymonosulfate oxidation: Role of Fe/Mn drives active species based on aluminum adsorption and synergistic promoted electron transfer

Conventional coagulation or enhanced coagulation water treatment produced mass floc sludge, which contained plenty of metals and organic matter. Floc sludge disposal and resource recycling was vital relevance and urgently needed. Here, we reported on the waste flocs recycling through in-situ manganese-aluminum-iron biochar (MAFBC) synthesized via one-step pyrolysis using potassium permanganate (KMnO4) oxidation- aluminum-iron composite flocculant coagulation for humic acid removal floc sludge as raw material. Compared with ex-situ loaded or similar types of biochar, MAFBC showed faster and efficient activation effect of peroxymonosulfate (PMS) to degrade tetracycline (TC). TC was rapidly removed within 1 min in MAFBC/PMS system with degradation rate constant Kobs was 1.825 min−1, which mainly attributed to the multiple promoting effects of manganese-aluminum-iron. Aluminum oxides facilitated TC adsorption and synergistic Fe/Mn further significantly promoted electron transfer on the surface of the MAFBC. Additionally, bimetallic structure of Fe/Mn and the CO functional group on MAFBC accelerated the formation of reactive species. The redox cycles of Fe2+/Fe3+ and Mn2+/Mn3+/Mn4+ promoted the formation of free radicals OH and SO4−. Moreover, O2– and 1O2 also assumed an important role for TC removal during active species evolution drived by Fe/Mn. This research provides a new perspective for in-situ design of economical and stable metal carbon-based water treatment activator, and make contributions to the utilization of waste flocs in water treatment.

Seeding Layer Effect on the Microstructure of Hydrothermally Grown α‐Manganese Dioxide Nanowires on Three‐Dimensional Graphene Foam

AbstractHydrothermal synthesis is a straightforward approach for producing high‐yield manganese dioxide (MnO2) nanostructures with efficient morphological control at low temperatures. This study investigates the microstructural dependency of hydrothermally grown α‐MnO2 nanowires (NWs) on pre‐treatment conditions on the substrate surface. Within this scope, α‐MnO2 NWs were synthesized on chemical vapor deposition (CVD)‐based graphene foam (GF) substrates pre‐treated via potassium permanganate (KMnO4) solution as a seeding layer with different concentrations (0.025, 0.050, 0.075, 0.1 M). A direct α‐MnO2 NWs growth (without pre‐treatment) was also performed on GF by hydrothermal method. The seeding layer effect on the NWs growth was elaborated to comprehend the process‐structure correlations by characterizing the resultant graphene foam/α‐MnO2 nanowires (GF/α‐MnO2 NWs) nanocomposites through Scanning Electron Microscopy (SEM), Raman Spectroscopy, X‐Ray Diffraction (XRD), and X‐Ray Photoelectron Spectroscopy (XPS). SEM, XRD, and Raman Spectroscopy revealed the successful acquisition of highly crystalline α‐MnO2 in one‐dimensional nanowire morphology on the high‐quality GF. Moreover, XPS results confirmed that all nanocomposites comprise α‐MnO2 and graphene without chemical degradation. Consequently, slight changes in solution concentration of seeding layers caused a noticeable alteration in the nanowire's structure, which could ensure effective control of nanocomposite properties without sacrificing the high purity of each component.

Watershed landscape characteristics and connectivity drive river water quality under seasonal dynamics

Landscape characteristics and connectivity are pivotal determinants of river water quality within the context of water quality management. They play particularly important roles in the spread of non-point source pollution. However, previous research has not investigated their combined effects, especially in the topographically and ecologically volatile Loess Plateau, China. This study applied machine learning and positive matrix factorization techniques to water quality monitoring data for the Wuding River basin, China, from 2017 to 2021 to assess the seasonal impacts of environmental factors on river water quality. The results showed that there were spatial and seasonal variations in pollution sources, and specific thresholds for the key landscape indices that influence water quality were identified. Landscape composition and configuration have the greatest influence on the water quality parameters during the dry season, whereas connectivity and landscape configuration are more critical during the wet season. The connectivity contributions to chemical oxygen demand, the potassium permanganate index, and total phosphorus in the wet season were 19.07%, 27.47%, and 5.08% greater than in the dry season, respectively. Connectivity also made a significant contribution to the composite water quality index, accounting for 33.46% in the dry season and 36.22% in the wet season. The positive matrix factorization model identified agricultural non-point sources and mixed pollutants as the main factors affecting water quality during the dry season, whereas erosion and mixed pollution sources dominated the wet season. Critical thresholds were established for the landscape indices that affected water quality, such as a landscape shape index below 18.5 and a grassland proportion above 65%. The results can be used to develop more effective water quality management strategies and illustrate the essential role played by connectivity when tailoring water quality management strategies to seasonal variations.