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International Journal of Molecular... May 2022It is known that ammonium has a higher permeability through anion exchange and bipolar membranes compared to K+ cation that has the same mobility in water. However, the...
It is known that ammonium has a higher permeability through anion exchange and bipolar membranes compared to K+ cation that has the same mobility in water. However, the mechanism of this high permeability is not clear enough. In this study, we develop a mathematical model based on the Nernst−Planck and Poisson’s equations for the diffusion of ammonium chloride through an anion-exchange membrane; proton-exchange reactions between ammonium, water and ammonia are taken into account. It is assumed that ammonium, chloride and OH− ions can only pass through membrane hydrophilic pores, while ammonia can also dissolve in membrane matrix fragments not containing water and diffuse through these fragments. It is found that due to the Donnan exclusion of H+ ions as coions, the pH in the membrane internal solution increases when approaching the membrane side facing distilled water. Consequently, there is a change in the principal nitrogen-atom carrier in the membrane: in the part close to the side facing the feed NH4Cl solution (pH < 8.8), it is the NH4+ cation, and in the part close to distilled water, NH3 molecules. The concentration of NH4+ reaches almost zero at a point close to the middle of the membrane cross-section, which approximately halves the effective thickness of the diffusion layer for the transport of this ion. When NH3 takes over the nitrogen transport, it only needs to pass through the other half of the membrane. Leaving the membrane, it captures an H+ ion from water, and the released OH− moves towards the membrane side facing the feed solution to meet the NH4+ ions. The comparison of the simulation with experiment shows a satisfactory agreement.
Topics: Ammonia; Ammonium Chloride; Ammonium Compounds; Anions; Chlorides; Nitrogen; Permeability; Water
PubMed: 35628589
DOI: 10.3390/ijms23105782 -
Effect of Substituents on the Homopolymerization Activity of Methyl Alkyl Diallyl Ammonium Chloride.Molecules (Basel, Switzerland) Jul 2022Among nitrogen-containing cationic electrolytes, diallyl quaternary ammonium salt is a typical monomer with the highest positive charge density, which has attracted the...
Among nitrogen-containing cationic electrolytes, diallyl quaternary ammonium salt is a typical monomer with the highest positive charge density, which has attracted the most attention, especially in the research on homopolymers and copolymers of dimethyl diallyl ammonium chloride (DMDAAC), which occupy a very unique and important position. In order to improve the lipophilicity of substituted diallyl ammonium chloride monomers under the premise of high cationic charge density, the simplest, most direct, and most efficient structure design strategy was selected in this paper. Only one of the substituents on DMDAAC quaternary ammonium nitrogen was modified by alkyl; the substituents were propyl and amyl groups, and their corresponding monomers were methyl propyl diallyl ammonium chloride (MPDAAC) and methyl amyl diallyl ammonium chloride (MADAAC), respectively. The effect of substituent structure on the homopolymerization activity of methyl alkyl diallyl ammonium chloride was illustrated by quantum chemical calculation and homopolymerization rate determination experiments via ammonium persulfate (APS) as the initiator system. The results of quantum chemistry simulation showed that, with the finite increase in substituted alkyl chain length, the numerical values of the bond length and the charge distribution of methyl alkyl diallyl ammonium chloride monomer changed little, with the activation energy of the reactions in the following order: DMDAAC < MPDAAC < MADAAC. The polymerization activities measured by the dilatometer method were in the order DMDAAC > MPDAAC > MADAAC. The activation energies Ea of homopolymerization were 96.70 kJ/mol, 97.25 kJ/mol, and 100.23 kJ/mol, and the rate equation of homopolymerization of each monomer was obtained. After analyzing and comparing these results, it could be easily found that the electronic effect of substituent was not obvious, whereas the effect of the steric hindrance was dominant. The above studies have laid a good foundation for an understanding of the polymerization activity of methyl alkyl diallyl ammonium chloride monomers and the possibility of preparation and application of these polymers with high molecular weight.
Topics: Ammonium Chloride; Ammonium Compounds; Nitrogen; Polymerization; Polymers
PubMed: 35897851
DOI: 10.3390/molecules27154677 -
Journal of Bacteriology Mar 1962Marshall, K. C. (Cornell University, Ithaca, N. Y.) and M. Alexander. Nitrification by Aspergillus flavus. J. Bacteriol. 83:572-578. 1962.-Aspergillus flavus has been...
Marshall, K. C. (Cornell University, Ithaca, N. Y.) and M. Alexander. Nitrification by Aspergillus flavus. J. Bacteriol. 83:572-578. 1962.-Aspergillus flavus has been shown to produce bound hydroxylamine, nitrite, and nitrate when grown in peptone, amino acid, or buffered ammonium media. Free hydroxylamine was not detected in these cultures, but it was found in an unbuffered ammonium medium in which neither nitrite nor nitrate was formed. Evidence was obtained for the presence of beta-nitropropionic acid in the filtrate of an actively nitrifying culture. Alumina treatment of an ammonium medium prevented the formation by growing cultures of nitrite and nitrate but not bound hydroxylamine. The effect of alumina treatment was reversed by the addition of 10(-3)m CeCl(3) to the medium. Extracts of the fungus contained peroxidase and an enzyme capable of catalyzing the production of nitrite from beta-nitropropionic acid. The nitrite-forming enzyme is apparently specific for beta-nitropropionate; no activity was found with nitromethane, nitroethane, and nitropropane as substrates. Nitrate was not reduced to nitrite nor was nitrite oxidized to nitrate by the hyphal extracts. The significance of these observations in nitrification by A. flavus is discussed.
Topics: Amino Acids; Ammonium Compounds; Aspergillus; Aspergillus flavus; Hydroxylamine; Hydroxylamines; Nitrates; Nitrification; Nitrites; Nitro Compounds; Oxidation-Reduction; Oxidoreductases; Propionates; Quaternary Ammonium Compounds
PubMed: 14470254
DOI: 10.1128/jb.83.3.572-578.1962 -
Journal of the American Chemical Society Mar 2018A combination of H NMR spectroscopy, DLS, and turbidity measurements reveal that polarizable anions engender both the Hofmeister and reverse Hofmeister effects in...
A combination of H NMR spectroscopy, DLS, and turbidity measurements reveal that polarizable anions engender both the Hofmeister and reverse Hofmeister effects in positand 2. Host 2 possesses two principal and distinctly different binding sites: a "soft" nonpolar pocket and a "hard" crown of ammonium cations. NMR spectroscopy reveals that anion affinity to both sites is comparable, with each site showing characteristic selectivities. NMR spectroscopy also reveals that anions competitively bind to the pocket and induce the Hofmeister effect in host-guest binding at very low concentrations (∼2 mM). Furthermore, the suite of techniques utilized demonstrates that anion binding to both sites leads to charge attenuation, aggregation, and finally precipitation (the reverse Hofmeister effect). Anion-induced precipitation generally correlated with affinity, and comparisons between the free host and its adamantane carboxylate (Ada-CO) complex reveals that the reverse Hofmeister effect is attenuated by blocking anion binding/charge attenuation at the nonpolar pocket.
Topics: Hydrocarbons; Ions; Magnetic Resonance Spectroscopy; Molecular Conformation; Quaternary Ammonium Compounds
PubMed: 29533064
DOI: 10.1021/jacs.8b00196 -
ChemMedChem Jan 2019Twenty-one mono- and biscationic quaternary ammonium amphiphiles (monoQACs and bisQACs) were rapidly prepared in order to investigate the effects of rigidity of a...
Twenty-one mono- and biscationic quaternary ammonium amphiphiles (monoQACs and bisQACs) were rapidly prepared in order to investigate the effects of rigidity of a diamine core structure on antiseptic activity. As anticipated, the bioactivity against a panel of six bacteria including methicillin-resistant Staphylococcus aureus (MRSA) strains was strong for bisQAC structures, and is clearly correlated with the length of non-polar side chains. Modest advantages were noted for amide-containing side chains, as compared with straight-chained alkyl substituents. Surprisingly, antiseptics with more rigidly disposed side chains, such as those in DABCO-12,12, showed the highest level of antimicrobial activity, with single-digit MIC values or better against the entire bacterial panel, including sub-micromolar activity against an MRSA strain.
Topics: Anti-Infective Agents, Local; Dose-Response Relationship, Drug; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Molecular Structure; Quaternary Ammonium Compounds; Structure-Activity Relationship; Surface-Active Agents
PubMed: 30358105
DOI: 10.1002/cmdc.201800622 -
Plant Signaling & Behavior 2015Nitrate (NO3(-)) and ammonium (NH4(+)) are the main forms of nitrogen available in the soil for plants. Excessive NH4(+) accumulation in tissues is toxic for plants and...
Nitrate (NO3(-)) and ammonium (NH4(+)) are the main forms of nitrogen available in the soil for plants. Excessive NH4(+) accumulation in tissues is toxic for plants and exclusive NH4(+)-based nutrition enhances this effect. Ammonium toxicity syndrome commonly includes growth impairment, ion imbalance and chlorosis among others. In this work, we observed high intraspecific variability in chlorophyll content in 47 Arabidopsis thaliana natural accessions grown under 1 mM NH4(+) or 1 mM NO3(-) as N-source. Interestingly, chlorophyll content increased in every accession upon ammonium nutrition. Moreover, this increase was independent of ammonium tolerance capacity. Thus, chlorosis seems to be an exclusive effect of severe ammonium toxicity while mild ammonium stress induces chlorophyll accumulation.
Topics: Adaptation, Physiological; Ammonium Compounds; Arabidopsis; Chlorophyll; Nitrates; Nitrogen; Plant Diseases; Stress, Physiological
PubMed: 25853545
DOI: 10.4161/15592324.2014.991596 -
Ecotoxicology and Environmental Safety Jan 2021High levels of ammonium in groundwater is a potential threat to drinking water security and ecological status. The role of dissolved organic matter (DOM) in mobilization...
High levels of ammonium in groundwater is a potential threat to drinking water security and ecological status. The role of dissolved organic matter (DOM) in mobilization of natural ammonium in groundwater is crucial but the intrinsic link between them has still been poorly understood. This study used high-pressure size exclusion chromatography (HPSEC) and fluorescence excitataion-emission-matrix spectra (EEMs) with parallel factor analysis (PARAFAC) to elucidate the influence of DOM characteristics in groundwater systems having contrastive ammonium levels in Dongting Plain, central Yangtze River. The results indicate that NH-N concentration in groundwater of western plain (0-16.75 mg/L) are much higher compared with southern plain (0-1.5 mg/L). The groundwater in western plain is in a more reductive environment and characterized by larger molecular weight (MW) of DOM and lower polydispersity (ρ), whereas DOM with relatively small molecular weight and high polydispersity is detected in the south with a more oxidative condition. The groundwater in western plain is characterized by lower fluorescence index (f) and biological index (BIX), and dominated by the high molecular weight terrestrial humic-like component and larger amounts of microbial humic-like components. Protein-like is the main component in groundwater of southern plain with higher f and BIX. The ammonium concentration in groundwater correlates well with molecular weight and increases significantly with the content of high molecular weight terrestrial humic-like component, indicating that mobilization of ammonium is more closely associated with the terrestrial organic matter of high molecular weight. This study further enriches the theory on mobilization of ammonium in Quaternary alluvial-lacustrine aquifer systems and provides theoretical basis for the local water supply security.
Topics: Ammonium Compounds; China; Environmental Monitoring; Factor Analysis, Statistical; Fluorescence; Groundwater; Rivers; Spectrometry, Fluorescence
PubMed: 33396090
DOI: 10.1016/j.ecoenv.2020.111779 -
Journal of the American Chemical Society Nov 2017Chiral metal-organic frameworks have attracted interest for enantioselective separations and catalysis because of their high crystallinity and pores with tunable shapes,...
Chiral metal-organic frameworks have attracted interest for enantioselective separations and catalysis because of their high crystallinity and pores with tunable shapes, sizes, and chemical environments. Chiral frameworks of the type M(dobpdc) (M = Mg, Mn, Fe, Co, Ni, Zn; dobpdc = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) seem particularly promising for potential applications because of their excellent stability, high internal surface areas, and strongly polarizing open metal coordination sites within the channels, but to date these materials have been isolated only in racemic form. Here, we demonstrate that when appended with the chiral diamine trans-1,2-diaminocyclohexane (dach), Mg(dobpdc) adsorbs carbon dioxide cooperatively to form ammonium carbamate chains, and the thermodynamics of CO capture are strongly influenced by enantioselective interactions within the chiral pores of the framework. We further show that it is possible to access both enantiomers of Mg(dobpdc) with high enantiopurity (≥90%) via framework synthesis in the presence of varying quantities of d-panthenol, an inexpensive chiral induction agent. Investigation of dach-M(dobpdc) samples following CO adsorption-using single-crystal and powder X-ray diffraction, solid-state nuclear magnetic resonance spectroscopy, and density functional theory calculations-revealed that the ammonium carbamate chains interact extensively with each other and with the chiral M(dobpdc) pore walls. Subtle differences in the non-covalent interactions accessible in each diastereomeric phase dramatically impact the thermodynamics of CO adsorption.
Topics: Adsorption; Ammonium Compounds; Carbamates; Carbon Dioxide; Magnesium; Metal-Organic Frameworks
PubMed: 28991466
DOI: 10.1021/jacs.7b09983 -
Scientific Reports Jun 2021Coral reefs, especially those located near-shore, are increasingly exposed to anthropogenic, eutrophic conditions that are often chronic. Yet, corals under unperturbed... (Comparative Study)
Comparative Study
Coral reefs, especially those located near-shore, are increasingly exposed to anthropogenic, eutrophic conditions that are often chronic. Yet, corals under unperturbed conditions may frequently receive natural and usually temporary nutrient supplementation through biological sources such as fishes. We compared physiological parameters indicative of long- and short-term coral health (day and night calcification, fragment surface area, productivity, energy reserves, and tissue stoichiometry) under continuous and temporary nutrient enrichment. The symbiotic coral Acropora intermedia was grown for 7 weeks under continuously elevated (press) levels of ammonium (14 µmol L) and phosphate (10 µmol L) as separate and combined treatments, to discern the individual and interactive nutrient effects. Another treatment exposed A. intermedia twice-daily to an ammonium and phosphate pulse of the same concentrations as the press treatments to simulate natural biotic supplementation. Press exposure to elevated ammonium or phosphate produced mixed effects on physiological responses, with little interaction between the nutrients in the combined treatment. Overall, corals under press exposure transitioned resources away from calcification. However, exposure to nutrient pulses often enhanced physiological responses. Our findings indicate that while continuous nutrient enrichment may pose a threat to coral health, episodic nutrient pulses that resemble natural nutrient supplementation may significantly benefit coral health and physiology.
Topics: Ammonium Compounds; Animals; Anthozoa; Calcification, Physiologic; Circadian Rhythm; Phosphates; Photosynthesis; Random Allocation; Seawater
PubMed: 34162916
DOI: 10.1038/s41598-021-92276-y -
PloS One 2014Biochar produced by pyrolysis of biomass can be used to counter nitrogen (N) pollution. The present study investigated the effects of feedstock and temperature on...
Biochar produced by pyrolysis of biomass can be used to counter nitrogen (N) pollution. The present study investigated the effects of feedstock and temperature on characteristics of biochars and their adsorption ability for ammonium N (NH4(+)-N) and nitrate N (NO3(-)-N). Twelve biochars were produced from wheat-straw (W-BC), corn-straw (C-BC) and peanut-shell (P-BC) at pyrolysis temperatures of 400, 500, 600 and 700°C. Biochar physical and chemical properties were determined and the biochars were used for N sorption experiments. The results showed that biochar yield and contents of N, hydrogen and oxygen decreased as pyrolysis temperature increased from 400°C to 700°C, whereas contents of ash, pH and carbon increased with greater pyrolysis temperature. All biochars could sorb substantial amounts of NH4(+)-N, and the sorption characteristics were well fitted to the Freundlich isotherm model. The ability of biochars to adsorb NH4(+)-N followed: C-BC>P-BC>W-BC, and the adsorption amount decreased with higher pyrolysis temperature. The ability of C-BC to sorb NH4(+)-N was the highest because it had the largest cation exchange capacity (CEC) among all biochars (e.g., C-BC400 with a CEC of 38.3 cmol kg(-1) adsorbed 2.3 mg NH4(+)-N g(-1) in solutions with 50 mg NH4(+) L(-1)). Compared with NH4(+)-N, none of NO3(-)-N was adsorbed to biochars at different NO3(-) concentrations. Instead, some NO3(-)-N was even released from the biochar materials. We conclude that biochars can be used under conditions where NH4(+)-N (or NH3) pollution is a concern, but further research is needed in terms of applying biochars to reduce NO3(-)-N pollution.
Topics: Adsorption; Ammonium Compounds; Biofuels; Biomass; Charcoal; Electric Conductivity; Hot Temperature; Hydrogen-Ion Concentration; Microscopy, Electron, Scanning; Nitrates; Nitrogen; Spectroscopy, Fourier Transform Infrared; X-Ray Diffraction
PubMed: 25469875
DOI: 10.1371/journal.pone.0113888