Mariusz B. Bogacki

Biodegradation and surfactant-mediated biodegradation of diesel fuel by 218 microbial consortia are not correlated to cell surface hydrophobicity

In this study, we elucidated the role of cell surface hydrophobicity (microbial adhesion to hydrocarbons method, MATH) and the effect of anionic rhamnolipids and nonionic Triton X-100 surfactants on biodegradation of diesel fuel employing 218 microbial consortia isolated from petroleum-contaminated soils. Applied enrichment procedure with floating diesel fuel as a sole carbon source in liquid cultures resulted in consortia of varying biodegradation potential and diametrically different cell surface properties, suggesting that cell surface hydrophobicity is a conserved parameter. Surprisingly, no correlations between cell surface hydrophobicity and biodegradation of diesel fuel were found. Nevertheless, both surfactants altered cell surface hydrophobicity of the consortia in similar manner: increased for the hydrophilic and decreased for the hydrophobic cultures. In addition to this, the surfactants exhibited similar influence on diesel fuel biodegradation: Increase was observed for initially slow-degrading cultures and the opposite for fast degraders. This indicates that in the surfactant-mediated biodegradation, effectiveness of surfactants depends on the specification of microorganisms and not on the type of surfactant. In contrary to what was previously reported for pure strains, cell surface hydrophobicity, as determined by MATH, is not a good descriptor of biodegrading potential for mixed cultures.

D- and T-optimum designs for the kinetics of a reversible chemical reaction

Abstract The purpose of our paper is to exemplify D-optimum designs for parameter estimation in the kinetics of a reversible chemical reaction and to find T-optimum designs for model discrimination, as a method of determining the order of reaction. Although the statistical methods are similar for consecutive and reversible reactions, the designs have markedly different properties. As a chemical example we use the esterification of ethanol and acetic acid. On the basis of this example we discuss the geometrical interpretation of D-optimum designs, which is strictly connected with the course of reaction and permits instructive comparisons of reversible and consecutive chemical processes. The methods of optimum experimental design provide an alternative to conventional designs for parameter estimation and model discrimination. We show how much more efficient the optimum design can be for parameter estimation than relying on a conventional design. We calculate a sequential T-optimum design and propose a statistical test verifying a hypothesis on the order of reaction. We also present the theoretical background of information matrices for non-linear models, D-optimum designs for parameter estimation and T-optimum designs for model discrimination.

PHVSICOCHEMICAL MODIFICATION OF COPPER EXTRACTANTS. A REVIEW.

ABSTRACT The modification of hydroxyoximes, ester and amides of pyridine carboxylic acids with various oxygen containing modifiers (alcohols, alkylphenols, ketones, esters, etc.) is reviewed. The modifiers form co-associates with the copper extractants changing, in this way, the active concentration of the monomer and blocking the active groups of the extractants. The structures of such associates predicted by molecular modeling are given.

Termination mechanism during the photo-induced radical cross-linking polymerization in the presence and absence of oxygen

The objective of this study was to characterize changes in the termination mechanism and in the rate coefficients during a light-induced polymerization occurring under continuous illumination and during the after-effect (after the irradiation has been discontinued) in the presence or in the absence of oxygen. The illumination was stopped at various double bond conversions. The polymerization of a model monomer-(diethylene glycol)dimethacrylate was analyzed using three termination models: monomolecular (I), bimolecular (II) and mixed (III) and the following parameters were estimated: kmt and kp[P˙]0 (Model I), kbt[P˙]0 and kp[P˙]0 (Model II) and kmt, kbt[P˙]0 and kp[P˙]0 (Model III), where kmt is the monomolecular termination rate coefficient, kbt is the bimolecular termination rate coefficient, kp is propagation rate coefficient and [P˙]0 denotes macroradical concentration at the beginning of the dark reaction. The parameters of the models were averaged over increasingly large dark conversion. Multistage statistical analysis of the results showed that over the conversion range studied, the bimolecular reaction was the main way of termination during continuous illumination, but during the after-effect termination mechanism changed with time of dark reaction from the bimolecular to the mixed one indicating an increasing importance of radical trapping. The obtained results suggest that oxygen accelerates the bimolecular termination, but pseudo first-order reaction with oxygen also contributes to the overall termination process. Moreover, the postpolymerization is more sensitive to negative influence of oxygen than the polymerization under continuous irradiation.

SEMI-EMPIRICAL (PM3) COMPUTATIONAL STUDIES OF THE ASSOCIATION OF ALKYL PYRIDINE MONOCARBOXYLATES WITH METHANOL AND WATER IMPLICATION FOR INTERFACIAL ACTIVITY AND THE EFFECT OF PHASE MODIFIERS

ABSTRACT Alkyl pyridine monocarboxylates can form associates with alcohols. The alcohol hydroxyl group is mainly bonded with oxygen atoms of the ester group, while the pyridine nitrogen is only slightly blocked. The degree of hydrogen-bonding at the different acceptor sites depends significantly on the position of the carboxyl group in the pyridine ring. Alkyl pyridine monocarboxylates can form hydrates with water molecules. Again the hydrogen bonds are mainly formed with the oxygen atoms of the ester group. Such hydration is limited in extraction systems containing alkyl isonicotinate and alkyl nicotinate, and only weak monohydrates with one water molecule bonded with the pyridine nitrogen can be formed. The oxygens of the ester group of alkyl picolinate can be, however, easily hydrated. This phenomenon is reflected in interfacial activity and interfacial concentration of the considered extractants.

Interfacial behavior of ACORGA CLX-50 and surface kinetics of copper extraction

Interfacial tension isotherms were determined and interpreted for ACORGA CLX-50. The hydration of extractant molecules in aqueous solution and at hydrocarbon/water interfaces was studied by molecular modelling. The usefulness of this technique to interpret the adsorption behavior was demonstrated. The interfacial kinetics was considered and relationships for various models of interfacial mechanism were derived and discussed. Despite its high hydrophobicity, ACORGA CLX 50 strongly adsorbs at the hydrocarbon/water interfaces and thus decreases effectively the interfacial tension. This high interfacial activity of ACORGA CLX 50 can be explained by the formation of hydrates. The interfacial tension isotherm can be well matched with the Szyszkowski equation. Molecular modelling suggests that ACORGA CLX 50 adsorbs at the hydrocarbon/water interface probably as a tetrahydrate containing two water molecules bonded to the same carbonyl oxygen atom (e.g., at position 3), one water molecule bonded to the oxygen atom of the second alkoxyl group (i.e., at position 5 when the hydration of carbonyl oxygen at position 3 is previously considered) and, finally, one water molecule bonded with the pyridine nitrogen atom. Positions 3 and 5 are equivalent. It is also shown that when the extraction of copper takes place in the kinetic regime, the reaction order with respect to ACORGA CLX 50 can change depending on the limiting step and the range of extractant concentration considered. Thus, a decrease of the extractant concentration from 10−5M to 3·10−3M causes a fall of the order with respect to ACORGA CLX 50 from 1 to 0 and 2 to 1 when the formation of the intermediate 1∶1 and final 2∶1 complexes are considered to be the limiting step, respectively.

Hydration and interfacial activity of methyl 8-pyridyloctanoates and extraction of copper(II) from chloride solutions

Abstract The interfacial tension of individual methyl 8-pyridyloctanoates containing the hydrophobic group at different positions of the pyridine ring was measured at the tolune water interface. The extraction of copper(II) fom chloride solutions with these reagents was studied. Considering solvent extraction, methyl 8-(2-pyridyl)octanoate had a worse orientation at the interface than methyl 8-(3-pyridyl)octanoate and methyl 8-(4-pyridyl)octanoate. PM3 semiempirical quantum chemical computing indicates that the oxygen of the carbonyl group forms hydrogen bonds with water molecules more easily than the second oxygen atom and the nitrogen in the pyridine ring. However, at the adsorption layer, this hydration is possible only for methyl 8-(2-pyridyl)octanoate. Methyl 8-(3-pyridyl)octanoate and methyl 8-(4-pyridyl)octanoate are strong copper extractants from chloride solutions, while extraction is not observed for methyl 8-(2-pyridyl)octanoate.

Influence of Alkyl Chain Length in 1-Alkylimidazol on the Citric Acid Transport Rate across Polymer Inclusion Membrane

Research, about citric acid transport, through the polymer inclusion membranes, have been carried out. Two different plasticizers – ONPOE and TBP and a series of carriers of tri-octylamine and 1-alkylimidazoles with carbons chain length of 10, 11, 12, 14, and 16 atoms were used. It was found out that for 1-alkylimidazoles values of the permeability coefficients obtained for TBP as plasticizer change in the range of 8.81*10−7 m/s to 1.92*10−6 m/s. When ONPOE was used as the plasticizer, the values change in the range of 1.43*10−9 m/s to 2.24*10−8 m/s. The value of the permeability coefficient for the membrane with TBP equals 3.49*10−7 m/s and is comparable with the value obtained for the TOA with this plasticizer, which equals 4.77*10−7 m/s TBP, therefore, it is able to simultaneously act as a plasticizer and carrier in membrane. Tested membranes are characterized by a high durability. The repeated 5-times, 24-hours cycles of research did not show any decrease in transport capacity of citric acid.

Effect of extractant on arsenic(V) recovery from sulfuric acid solutions

Extraction of arsenic(V) from sulfuric acid solutions with various extractants in multistage counter-current extraction-stripping systems was compared. The extraction ability of the extractants studied showed the following order: ENIM 100>TBP=CYANEX 923>2-methylhexanol. The extraction depends significantly on the number of extraction stages and the phase ratios in extraction. The effects of the number of stripping stages and the phase ratio in stripping are less important.

Interfacial activity of dipentyl pyridinedicarboxylates at the hydrocarbon/water interface

Abstract Interfacial activity of dipentyl pyridinedicarboxylates was studied in model extraction systems. It was found that the interfacial activity depends on the positions of the ester groups and changes in the following order: dipentyl pyridine-2,5-dicarboxylate>dipentyl pyridine-2,4-dicarboxylate>dipentyl pyridine-2,3-dicarboxylate>dipentyl pyridine-3,5-dicarboxylate. The experimental interfacial data are in agreement with the molecular modelling of various dipentyl pyridinedicarboxylate molecules.