Synthesis of a novel highly dispersed manganese oxide on porous calcium silicate for catalytic oxidation of toluene

Herein, a series of novel porous calcium silicate (PCS)-supported manganese oxides (MnOx) catalysts are first prepared by impregnation method using three different manganese precursors (manganese acetate, manganese nitrate and manganese...

Preparation of Mn2+ Doped Piperazine Phosphate as a Char-Forming Agent for Improving the Fire Safety of Polypropylene/Ammonium Polyphosphate Composites

A piperazine phosphate doped with Mn2+ (HP-Mn), as a new char-forming agent for intumescent flame retardant systems (IFR), was designed and synthesized using 1-hydroxy ethylidene-1,1-diphosphonic acid, piperazine, and manganese acetate tetrahydrate as raw materials. The effect of HP-Mn and ammonium polyphosphate (APP) on the fire safety and thermal stability of polypropylene (PP) was investigated. The results showed that the combined incorporation of 25 wt.% APP/HP-Mn at a ratio of 1:1 endowed the flame retardant PP (PP6) composite with the limiting oxygen index (LOI) of 30.7% and UL-94 V-0 rating. In comparison with the pure PP, the peak heat release rate (PHRR), the total heat release (THR), and the smoke production rate (PSPR) of the PP6 were reduced by 74%, 30%, and 70%, respectively. SEM and Raman analysis of the char residues demonstrated that the Mn2+ displayed a catalytic cross-linking charring ability to form a continuous and compact carbon layer with a high degree of graphitization, which can effectively improve the flame retardancy of PP/APP composites. A possible flame-retardant mechanism was proposed to reveal the synergistic effect between APP and HP-Mn.

Soybean Nutrition in a Novel Single-Nutrient Source Hydroponic Solution

Hydroponic systems are efficient for studying plant nutrition. It is often desirable to adjust individual nutrients for unique species’ needs and/or to create multiple nutrient deficiencies within the same study. However, this is challenging to do with traditional solutions as nutrients are generally added as dual nutrient salts, such as when varying phosphorus (P) concentration also affects nitrogen concentration; potentially, the chemical form of the nutrient taken up when ammonium phosphate is the source for P. This can create unintended consequences with nutrients other than those intended for adjustment. A new hydroponic system has been created to allow for nutrient deficiencies using single-nutrient sources, including ammonium nitrate; phosphoric, sulfuric, hydrochloric, and boric acids; potassium, calcium, magnesium, zinc, and copper carbonates; manganese acetate; sodium molybdate; iron EDDHA; with HEDTA as an additional chelate. This nutrient solution was compared to a traditional “Hoagland” hydroponic solution to grow soybean (Glycine max (L.) Merr). Additional treatments included alteration of pH in the new solution as well as evaluating varying levels of calcium, magnesium, and manganese. This new solution proved effective, as soybean was grown to maturity and performed as well as the traditional Hoagland solution. Adjusting pH downward with hydrochloric acid resulted in healthy plants, but solution pH was not adequately buffered. Adjusting pH with acetic acid resulted in toxicity. Further work is required to provide better pH buffering and approximately align tissue nutrient concentrations with field-grown soybean.

Exploring efficient manganese oxides catalyst for ozone decomposition and its deactivation induced by water vapor

A series of MnOx catalysts supported by carbon sphere were prepared by calcining mixtures of manganese acetate and carbon spheres under nitrogen atmosphere, and their performances for ozone decomposition under...

Preparation of MnOx/CNTs Catalyst by in-Situ Precipitation Method For Low-Temperature NO Reduction with NH3

Background: V2O5–WO3(MoO3)/TiO2 catalyst, as the core of selective catalytic reduction of NO with NH3 (SCR) has some drawbacks, such as high working temperature window (300-400oC), the toxicity of V-based catalyst and so on. Therefore, development of the catalyst with better low temperature denitration catalyst and weaker toxicity is necessary. Objective: Highly dispersed MnOx/CNTs catalysts with excellent denitration activity at 80-180oC, and weaker toxicity of MnOx. It is worth noting that an in-situ precipitation method based on the reaction of manganese acetate and sodium carbonate, which is advantageous to the in-situ deposition of active component, and the catalytic activity. Methods: MnOx/CNTs catalysts with different Mn/C molar ratio were fabricated by in-situ precipitation method due to the reaction of manganese acetate and sodium carbonate. And the microstructure, crystalline property, the content of surface element, valence state, redox property, and catalytic activity was confirmed by FESEM, TEM, XRD, XPS, TPD, and fixedbed reactor. Results: The as-prepared MnOx/CNTs catalysts exhibit outstanding low temperature SCR activity. And the NO conversion of the optimum 1.2% MnOx/CNTs catalyst reached 57.4-89.2% at 80-180oC, which resulted from the amorphous MnOx catalysts, higher ratio of Mn4+/Mn3+ and OS/(OS+OL). Conclusion: MnOx/CNTs catalysts have been prepared by the in-situ precipitation method based on the reaction of manganese acetate and sodium carbonate. And the resultant MnOx/CNTs catalysts presented excellent low temperature denitration activity between 80oC and 180oC. Among them, the 1.2% MnOx/CNTs catalyst exhibited the first rate low temperature denitration activity, and the denitration activity attained 57.4-89.2%, which may be owing to the presence of the weakly crystalline or amorphous MnOx, higher ratio of Mn4+/Mn3+ and OS/(OS+OL).

COORDINATION PROPERTIES OF NITRO-SUBSTITUTED 5,15-DIPHENYL-3,7,13,17-TETRAMETHYL-2,8,12,18-TETRAETHYLPORPHYRIN WITH MANGANESE ACETATE IN PYRIDINE AND ACETIC ACID

The synthesis of 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin and its nitro substituted was carried out. Nitro groups are located in meso-positions of the tetrapyrrole macrocycle and (or) para-positions of the phenyl rings. The synthesized porphyrins are characterized by a set of modern research methods: electron absorption spectroscopy; IR and nuclear magnetic resonance spectroscopy 1H. The reactions of the formation of manganese complexes with nitro-substituted 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin and their stability in organic solvents are studied. It was found that the rate of reactions of formation of manganese complexes in pyridine with the introduction of nitrogroups in 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphine grows as the degree of deformation of the tetrapyrrole macrocycle increases. Obviously, in this case, not only the stretching of NH bonds, due to the presence of electron-withdrawing substituents (NO2) in the para positions of the phenyl rings, makes a decisive contribution to the energy of the transition state, but also the increase in the basicity of tertiary nitrogen atoms, which form strong bonds in the transition state with a solvated cation of salt. In acetic acid, the macrocycle deformation effect leads to a decrease in the reaction rate, which is due to the specific solvation of the porphine reaction center by acetic acid molecules. It was found that steric distortions of the planar structure of porphyrins have relatively little effect on the kinetic parameters of the solvoprotolytic dissociation of manganese complexes of 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin and its nitro-substituted ones. This is probably due to the fact that the coordination of the manganese cation results in a more planar structure of the porphyrin macrocycle. The decrease in the dissociation reaction rate with an increase in the number of nitrogroups in 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrine is due to the influence of the negative inductive effect of nitrogroups, which reduces the effective charge in the macrocycle on nitrogen atoms that are attacked by a solvated proton.

Synthesis and characterization of Li2MnO3 nanoparticles using sol-gel technique for lithium ion battery

Nanoparticles of Li2MnO3 were fabricated by sol-gel method using precursors of lithium acetate and manganese acetate, and citric acid as chelating agent in the stoichiometric ratio. TGA/DTA measurements of the sample in the regions of 30 °C to 176 °C, 176 °C to 422 °C and 422 °C to 462 °C were taken to identify the decomposition temperature and weight loss. The XRD analysis of the sample indicates that the synthesized material is monoclinic crystalline in nature and the calculated lattice parameters are 4.928 Å (a), 8.533 Å (b), and 9.604 Å (c). The surface morphology, particle size and elemental analysis of the samples were observed using SEM and EDAX techniques and the results confirmed the agglomeration of nanoparticles and, as expected, Li2MnO3 composition. Half cells of Li2MnO3 were assembled and tested at C/10 rate and the maximum capacity of 27 mAh/g was obtained. Charging and discharging processes that occurred at 3 V and 4 V were clearly observed from the cyclic voltammetric experiments. Stability of the electrodes was confirmed by the perfect reversibility of the anodic and cathodic peak positions observed in the cyclic voltammogram of the sample. The Li2MnO3 nanoparticles exhibit excellent properties and they are suitable for cathode materials in lithium ion batteries.

Synthesis and Antimicrobial Activity of Metal-Containing Linseed Oil-Based Waterborne Urethane Oil Wood Coatings

In this study, the antimicrobial agents of mono(hydroxyethoxyethyl)phthalate (M(HEEP)2) with different metal of M = Zn, Mn, Pb, and Ca were synthesized from diethylene glycol (DEG), phthalic anhydride (PA), and divalent metal acetates including calcium acetate, zinc acetate, manganese acetate, and lead acetate, respectively. The waterborne urethane oil (WUO) dispersions synthesized from linseed oil, diisocyanates (hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI)), dimethylolpropionic acid at NCO/OH molars of 0.9, by acetone processing method were described as in our previous report. The M(HEEP)2 antimicrobial agents as well as the commercial nanosilver powder were added into WUO dispersions as the antimicrobial coatings. The effects of various antimicrobial agents and dosages (0.0, 0.2, 0.6, 0.8, 1.0, 2.0, and 4.0 phr) on antimicrobial activity of WUO films against gram-negative bacterium of Escherichia coli, gram-positive bacterium of Staphylococcus aureus, brown-rot fungus of Gloeophyllum trabeum, and white-rot fungus of Lenzites betulina were assessed. In addition, the film properties of the best antimicrobial WUO coatings were also examined. The results showed that the antimicrobial agents of mono(hydroxyethoxyethyl) phthalate M(HEEP)2 (M = Zn, Mn, Pb, and Ca) powders should certainly be synthesized by FTIR, 1H-NMR, 13C-NMR, and energy-dispersive X-ray spectroscopy (EDS) identifications and the yields of them were 43–55%. The results also revealed that the WUO film synthesizing with HDI films containing Zn(HEEP)2 of 2.0 phr and Pb(HEEP)2 of 0.4 phr had the best antibacterial activity for E. coli and S. aureus, respectively. The IPDI films containing Zn(HEEP)2 of 1.0 phr had the best antibacterial activity for both E. coli and S. aureus. For antifungal activity, the WUO film synthesizing with HDI films containing Pb(HEEP)2 of 0.8 phr and Zn(HEEP)2 of 2.0 phr as well as IPDI films containing Mn(HEEP)2 of 0.2 phr and Zn(HEEP)2 of 4.0 phr had the best performances against G. trabeum and L. betulina, respectively. Comparing with commercial nanoAg powder, the Zn(HEEP)2 and Pb(HEEP)2 had a superior antifungal efficiency for G. trabeum and L. betulina, while it had a slightly inferior efficiency in the antibacterial activity for E. coli and S. aureus. On the properties of WUO films, adding metal-containing antimicrobial agents could slightly enhance the thermal stability, but lowered the gloss of all films, however, the Tg value increased for HDI film and decreased for IPDI film. In addition to this, they had no significant difference in the film properties including hardness, impact resistance, bending resistance, adhesion, mass retention, and light-fastness between the WUO films with and without adding antimicrobial agents.

The Design of ZnO Nanorod Arrays Coated with MnOx for High Electrochemical Stability of a Pseudocapacitor Electrode

Tremendous efforts have been made on the development of unique electrochemical capacitors or pseudocapacitors due to the overgrowing electrical energy demand. Here, the authors report a new and simple strategy for fabricating hybrid MnOx-coated ZnO nanorod arrays. First, the vertically aligned ZnO nanorods were prepared by chemical bath deposition (CBD) as a template providing a large surface area for active material deposition. The manganese oxide was subsequently coated onto the surface of the ZnO nanorods to form a hybrid MnOx-coated ZnO nanostructure by anodic deposition in a manganese acetate (MnA)-containing aqueous solution. The hybrid structure of MnOx-coated ZnO nanorod arrays exhibits a large surface area and high conductivity, essential for enhancing the faradaic processes across the interface and improving redox reactions at active MnOx sites. A certain concentration of the deposition solution was selected for the MnOx coating, which was studied as a function of deposition time. Cyclic voltammetry (CV) curves showed that the specific capacitance (SC) of the MnOx-coated ZnO nanostructure was 222 F/g for the deposition times at 10 s when the concentration of MnA solution was 0.25 M. The unique hybrid nanostructures also exhibit excellent cycling stability with >97.5% capacitance retention after 1200 CV cycles. The proposed simple and cost-effective method of fabricating hybrid nanostructures may pave the way for mass production of future intelligent and efficient electrochemical energy storage devices.

Synthesis of Lithium Mangan Oxide (LiMn2O4) Using Solution Method for Lithium Ion Battery Catodes Materials

Synthesis of Lithium Manganese Oxide (LiMn2O4) for Lithium Ion Battery Cathodes with Solution Method has been conducted. This experiment was carried out using the solution method. In this study, the synthesis was carried out by varying the calcination temperature. The raw materials used were Lithium Acetate (C2H3O2Li), Manganese Acetate (C4H6MnO4.4H2O), Hydrochloric Acid (HCl), and Ethanol (C2H5OH) as solvents which were dissolved to become LiMn2O4 precursors. Synthesis was carried out at calcination temperatures of 600oC, 700oC and 800oC, for 4 hours then pounded with a mortar until smooth. The characterization includes: The results of the STA test at 280oC-380oC showed a mass decrease of 11.9973% due to the release of mass of water vapor and decomposition of C4H6MnO4.4H2O raw material. XRD analysis shows that the increase in peak temperature of the LiMn2O4 phase intensity is getting sharper, the peak showing the impurity Li2O phase decreases. SEM analysis results show that the higher the calcination temperature, the larger the particle size is formed, because in the calcination process the densification process occurs.