Adam Jezierski

Organic radicals and paramagnetic metal complexes in municipal solid waste composts. An EPR and chemical study

Abstract The physicochemical properties of composted municipal solid wastes (MSW) were investigated by chemical and spectroscopic methods (EPR, NMR, IR, UV-Vis, ICP). Transformations of the composted organic matter during 150 days were observed. The water content was controlled in the composts; in some cases the composted MSW were nitrogen enriched by urea addition. The maturation of the composts was observed using standard methods. Quantitative EPR measurements were made on isolated humic and fulvic acids; the concentration of semiquinone free radicals and g parameters were determined. The maximum radical concentration (1.2 · 10 17 spins/gram) in isolated humic acids was observed in about the 6th week of the composting process in good quality composts. Moreover, distinct linear changes in g parameters of isolated humic acids (HA) from 2.0031 to 2.0037 were observed during the composting process. These changes were correlated to increasing E 4 /E 6 ratio characterizing the intensity of the oxidation processes and formation of oxygen-rich functional groups. The heavy metal (Cu, Fe, Mn, Pb) concentrations were examined in the composts and humic (HA) and fulvic acid (FA) fractions. The increase of copper binding by HA extracted from composts enriched in nitrogen was observed;the coordination sites of the ligand were characterized on the basis of EPR spectra. The various Fe(III) and Mn(II) complexes in the HA and FA fractions detected by EPR were used as additional indicators of oxidation-reduction processes in the composts.

EPR investigations of structure of humic acids from compost, soil, peat and soft brown coal upon oxidation and metal uptake

Free radical concentration and theirg-values in humic acids (HA) isolated from various sources were studied by quantitative EPR technique. EPR data for HA formed during composting and natural humification processes occurring in soil, peat and brown coal are given. In more detail the EPR data were analyzed for brown coal HA under carbonization, air oxidation (150°C) as well as metal uptake (Ca(II), Zn(II), Cd(II), Hg(II), Co(II), Ni(II) and Cu(II)) and NO2 reaction. Two groups of metal complexes were distinguished on the basis of their interaction with free radicals in HA. Ca(II), Zn(II), Cd(II) and Hg(II) ions increase free radical concentration, while Co(II), Ni(II) and Cu(II) ions quench the radicals compared to the raw HA. This phenomenon can be explained either by the strong interaction of the metal ions with active centres responsible for the quinone-hydroquinone-semiquinone equilibria, and/or by the antiferromagnetic interaction between radical spins and metal d orbitals. Gaseous ammonia was found to be a very useful base easily penetrating the solid matrix of HA and strongly influencing the equilibria. β-Diketone groups present in HA react with NO2 yielding iminoxy radicals. In the HA-metal complexes these structural units are engaged in metal coordination which lowers effectiveness of the iminoxyl synthesis.

Microstructure and structural transition in microemulsions stabilized by aldonamide-type surfactants.

Significant efforts were undertaken to characterize the microstructure and structural properties of water-in-oil (w/o), oil-in-water (o/w), and bicontinuous (bc) microemulsions composed of N-alkyl-N-methylgluconamides (n-alkyl = n-C(12)H(25), n-C(14)H(29), n-C(16)H(33)) and n-alcohols (ethanol, n-propanol, n-butanol) or iso-alcohols (iso-propanol, iso-butanol) as cosurfactants, as well as iso-octane and water. The internal structure of so created four-component system was elucidated by means of an analysis of isotropic area magnitudes in phase diagrams and conductivity measurements. Dynamic light scattering (DLS) measurements provided the microemulsion size and polydispersity. Polarity and viscosity of microemulsion microenvironment were acquired by means of electron paramagnetic resonance (EPR), UV-vis absorption spectroscopy (in the case of w/o droplets), and steady-state fluorescence (SSF) (in the case of o/w droplets). The results show that both the surfactant and the cosurfactant types affect the shape and extent of microemulsions. The size of droplets depends strongly on the type of examined microemulsion and the type of cosurfactant (linear or brunched) but is almost independent of the length of the surfactant alkyl chain. The size of microemulsion droplets ranges from 8.1 to 22.6 nm and from 3.7 to 14.3 nm respectively, for o/w and o/w microemulsions, making them good candidates for both template-based reactions and household components solubilizing media.

Biocompatible microemulsions of dicephalic aldonamide-type surfactants: Formulation, structure and temperature influence

The temperature effects upon microemulsion systems composed of dicephalic N-dodecyl-N,N-bis[(3-D-aldonylamido)propyl]amines C12-DX (gluconyl GA or lactobionyl LA)/iso-butanol/hydrophilic (diethylene glycol monoethyl ether) or hydrophobic (iso-octane) oils/water were investigated by evaluating isotropic area magnitudes in the pseudoternary phase diagrams, as well as droplet characteristics by electron paramagnetic resonance (EPR) and dynamic light scattering (DLS) spectroscopies at 25, 40 and 55 degrees C. We concluded that in the examined systems a cosurfactant, such as middle-chain alcohol, was needed to obtain large mesophase isotropic areas. The phase behavior and structure of the examined systems were temperature insensitive but they were intimately determined by the nature of the C12-DX and the polarity of the oil phase. By adjusting the nature of the oil, as well as the surfactant hydrophilicity, the performed isotropic systems containing low amounts of nonaggressive surfactant could be formulated successfully. Interfacial properties and the dynamic structure of the surfactant/cosurfactant monolayer were studied by the spin probe technique using the 16-doxylstearic acid methyl ester (16-DSE) as the appropriate probe. The polarity of the interface was not affected by temperature but the interface rigidity was dependent upon the nature of the surfactant and oil as well as on temperature. The size of the dispersed domains, evaluated by dynamic light scattering (DLS), was found to be a function of temperature, surfactant content and type of additives. The investigated o/w microemulsions (i.e., ranging from 3.0 to 8.8 nm) constituted promising templates for a variety of syntheses of nanostructures with small size and high-capacity solubilizing media.

Impact of conventional and no-tillage management on soil amino acids, stable and transient radicals and properties of humic and fulvic acids☆

Abstract While several studies have documented the effect of no-till (NT) and conventional-till (CT) practices on soil organic matter and nutrients, very limited information is available on the effect of tillage practices on amino acids in soil. This study was conducted to measure the concentrations of bound amino acids in humic (HA) and fulvic acids (FA) in samples collected from soils under NT and CT management. Samples were obtained from two long-term studies at the Horseshoe Bend Experimental Area and at the Bledsoe Research Farm in Georgia, USA. The total amount of bound amino acids in HA was higher in NT than in CT samples. In contrast, the concentration of bound amino acids in FA was higher in CT than in NT samples. Neutral amino acids dominated in all samples of HA and FA. Acidic amino acids had the lowest concentrations. In all samples of HA and FA, the dominant amino acids were: glutamic acid, alanine, glycine and valine. β-alanine and lysine concentrations in HA and FA were higher in NT than in CT, indicating a higher microbial biomass in NT soils. Proline concentrations in FA were higher in CT than in NT samples. Electron paramagnetic resonance (EPR) was applied to characterize HA and FA extracted from soils under NT and CT. The level of native radicals for each sample of HA and FA was estimated. Strong effects of gaseous ammonia on spin concentration enhancement and also higher values of g- value were found to be associated with the formed “transient” radicals. HA from NT management was characterized by higher molecular weight and a higher degree of condensation of aromatic constituents than HA from CT.

Electron paramagnetic resonance (EPR) investigations of lichens - 1 : effects of air pollution

Electron paramagnetic resonance (EPR) investigations were carried out on more than 800 samples of lichens from Lower Silesia, southwest Poland. A statistically confirmed correlation between annual average concentration of sulphur dioxide in the atmosphere and concentration of semiquinone radicals in Hypogymnia physodes thalli was found. Similar results were obtained for Umbilicaria species from the Karkonosze Mountains. Distribution of semiquinone radicals in lichen thalli was also investigated. The action of nitrogen dioxide on Umbilicaria species resulted in the synthesis of iminoxy radicals in the thalli. The intensification of the semiquinone free radical production in lichen thalli from atmospherically polluted environments and the degradation of lichen acids to β-diketone compounds would appear to be parallel processes. The properties of the iminoxyls derived from β-diketones in the lichen matrix (anisotropic spectra at room temperature) and in organic solutions after extraction procedure were also examined by EPR.

Influence of metal ions binding on free radical concentration in humic acids. A quantitative electron paramagnetic resonance study

Abstract The influence of metal ions, e.g. Co(II), Cu(II), Mn(II), Ni(II), Fe(II), on free radical concentration in humic acids isolated from soil, peat and compost was investigated by electron paramagnetic resonance (EPR). The results show that metal ions with unfilled d-shell exhibit antiferromagnetic interactions with semiquinone radicals. Moreover, coordinated metals shift the quinone–semiquinone–hydroquinone equilibrium in the macromolecular matrix of humic acids. A strong decrease of semiquinone radical concentration in humic acid–metal complexes is observed. This effect is caused by interactions of metal ions with oxygen-containing stable radicals occurring in the aromatic systems of humic acids. Furthermore, the effect of metal coordination on free radical concentration in humic acids–metal complexes depends on the humic acid origin. FTIR spectroscopy was also used as an additional tool for studies of the metal ions interactions with carboxylic groups.

Sites of copper binding in Streptomyces pilosus

Copper abstraction from aqueous solutions by Streptomyces pilosus was studied. Comparison of the amount of metal accumulated by living and killed cells as well as by isolated cell wall preparations, indicated that the cell interiors of the organism play an important role in the Cu (II) ions biosorption process. This was confirmed by electron microscope and EPR examinations. The EPR spectra showed that accumulated copper formed complexes with CuO4 and CuO2N2 or CuO3N chromophores. These complexes were found in the whole cells (live and dead). However, in the case of isolated cell walls, the complex with CuCuO2N2 or CuO3N chromophore was absent.

The effect of nonadec(en)ylresorcinol on the fluidity of liposome and erythrocyte membranes.

The effect of alk(en)ylresorcinol homologs (5-(n-nonadecyl)- and 5-(n-nonadecenyl)resorcinol) on the mobility of 5-doxyl- and 12-doxylstearate spin probes incorporated into DMPC, DMPC-cholesterol and erythrocyte membranes was studied. It was found that both homologs affect the properties of hydrophobic environment of the membranes: (1) In DMPC vesicles both homologs induce an increase in the order parameter of 5-doxylstearate at temperatures of Tc and above. (2) At higher concentrations of both homologs a decrease in mobility of the 12-doxylstearate was also observed. (3) In the presence of cholesterol in the liposome membrane the influence of alk(en)ylresorcinols on the mobility of spin probes was much greater, depending on the cholesterol content and the position of the probe in the bilayer. (4) In natural membranes (erythrocyte ghosts) both alkyl- and alkenylresorcinols induced a decrease of mobility in the region of 12-doxylstearate as well as in the region closer to the polar head groups of lipids (5-doxylstearate).

The effect of annexin IV and VI on the fluidity of phosphatidylserine/phosphatidylcholine bilayers studied with the use of 5-deoxylstearate spin label.

An effect of annexin IV and VI on the fluidity of phosphatidylserine/phosphatidylcholine (PS/PC) membranes was studied by spin labeling technique with the use of 5‐doxylstearic acid. It was found that calcium ions at micromolar concentrations induced a marked decrease in the order parameter of PS/PC membranes. This effect was completely abolished by both annexins. The influence of annexins on the mobility of fatty acid chains in the studied region in PE/PC membranes was insignificant.