Decontamination of oil-polluted soil by cloud point extraction

An extraction procedure based on cloud point phase separation of nonionic surfactants was used to remove oil contamination from soils. The detergent employed was Triton X-114, and its clouding behavior was monitored by means of a fluorescence probe. Changes in the I (1)I (3) ratio of pyrene indicated gradual dehydration of the detergent micelles upon heating. The rate of phase separation, and the volume and water content of the micellar phase were determined. In the practical clean-up, 85-98% of the oil present in the soil was found to enter the micellar phase of the separated washing liquid. A 15-min washing time with 3-5% detergent was found to be sufficient for this degree of contaminant removal from soil containing 0.009-0.017% oil, using a liquid:solid ratio of 5:2. The extraction efficiency decreased with increasing carbon content of the soil. The process holds promise for large-scale treatment of oil-polluted soils.     

Direct analysis of thin-layer chromatographic spots of narcotics by means of diffuse reflectance Fourier transform infrared spectroscopy

The technique of diffuse reflectance Fourier transform infrared spectrometry (DRIFT) as an in situ detection method was used for the qualitative and quantitative analysis of drugs (heroin, cocaine and codeine) separated by thin layer chromatography.It was found that at a given interferometer throughput and detector sensitivity the quality of the spectrum depends strongly in the type of the chromatographic thin layer used. A detection limit of approx. 2 g was attained on a microcrystalline cellulose thin layer with a dynamically aligned Bio-Rad Digilab FTS 60A/896 type interferometer and room temperature DTGS detector. A reliable qualitative analysis can be made with as little as 10 to 15 g drug per spot.     

Theoretical implications involved in the DDRP method

The aim of this paper is to prove that safe success in finding reaction paths (RPs) can only be expected from global path-determining methods. Some extensions of the mathematical arguments leading to the introduction of the DDRP (dynamically defined reaction path) method have been sketched. Four cases involving relaxation of analyticity, variability of the gradient field, minimum energy (reaction) paths (MEPs) and golf pocket holes on the potential energy surface (PES), and the rather strange consequences of the main theorem of the DDRP method giving a rigorous mathematical basis to chemical intuition in reaction kinetics have been discussed. The discussions show that the DDRP method - when changing the conditions and parameters - may, in essence, involve all other global methods. It has been shown that the DDRP method works in a stable way even for non-analytic though smooth energy functions; moreover, the gradient field can be replaced by other vector fields resulting in better convergence to the reaction path. As a by-product, the question of the existence of MEPs can safely be handled and golf pocket holes are constructed on the PES in order to prove that local methods have chance to search faithfully the RPs in complicated systems only if the energy function can be restored from its arbitrarily small pieces.This work was presented in parts at the 8th International Congress of Quantum Chemistry, Prague, Czech Republic, June 19–23,1994; Addendum to the Book of Abstracts of the 8ICQC: P/I-129.     

Extraction separation of Sr2+ from Ba2+ in the system cobalt dicarbollide-polyethylene glycol-nitrobenzene-CCl4-cyclohexaned iaminetetraacetate

The kinetics of Sr and Ba distribution both for extraction and back-extraction processes has been investigated. The influence of the equilibrium pH, the CDTA concentration and the Na/Li ratio on the distribution of the metals to be separated was established. Separation factors (Ba/Sr) achieved were not altered by replacing PEG 400 as the synergic agent by the cheaper technical product Slovafol 909. Practical hints for carrying out the separation for analytical purposes. are given.     

Extraction of cesium and barium by dicarbollide and polyethylene glycol in the presence of alkylammonium cations

The extraction of cesium and barium cations into nitrobenzene and 60% (vol.%) nitrobenzene +40% CCl₄ mixture in the presence of dicarbollide (+Slovafol 909), and primary alkylammonium cations has been studied. Extraction constants determined for three methylammonium cations correlate well with their hydration enthalpies. Reverse order of the hydrophobicity of methylammonium cations (competition with bare Cs⁺ ion) and of their tendency to enter the polyethylene glycol complex (competition with polyethylene glycol complexed Cs⁺ and Ba²⁺ ions) is recorded. The possibility of the regeneration of the organic phase after stripping of Cs⁺ and Ba²⁺ ions with methylammonium cations has been investigated.     

On Lipschitz property of solutions of functional equations

In this work it is proved that under certain conditions the continuous vector-valued solutionsf of the functional equation

Electrochemical behaviour of a series of Fe(III) complexes with tetradentate Schiff base ligands

Summary The electrochemical reduction of the Fe(III) complexes with a series of substituted N,N-Ethylenebisacetonimines was investigated by cyclic voltammetry in acetonitrile solution at a platinum electrode. The substituent does not significantly influence the redox properties of the studied complexes. The symmetry of the redox orbital is responsible for the observed behaviour of the complexes.

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Elektrochemisches Verhalten einer Reihe von Fe(III)-Komplexen mit vierzähnigen Schiffschen Basen als Liganden

Zusammenfassung Die elektrochemische Reduktion der Fe(III)-Komplexe einer Reihe von substituierten N,N-Ethylenbisacetoniminen wurde mittels cyclischer Voltammetrie in Acetonitril an einer Platinelektrode untersucht. Der Substituent beeinflußt die Redoxeigenschaften der untersuchten Komplexe nicht signifikant. Das beobachtete Verhalten der Komplexe wird von der Symmetrie des Redoxorbitals bestimmt.

     

Comparative voltammetric study of 2,4-dinitrophenol (DNP), albumin and DNP-albumin as an analytical approach to the use of DNP as a universal label in immunoelectrochemical assays

A comparative electrochemical study of 2,4-dinitrophenol (DNP), albumin and DNP-albumin has been carried out at a hanging mercury drop electrode, in order to use DNP as a universal label in immunoelectrical assays. Several electrochemical techniques have been used. Differential pulse voltammetry has proved to be the most suitable. Wide dynamic linear ranges (more than three orders of magnitude for DNP-albumin) and low detection limits have been achieved (5 x 10(-10)M, 2 x 10(-10)M, 3 x 10(-12)M for DNP, albumin and DNP-albumin, respectively). Good reproducibility has been obtained in all cases (R.S.D. < 2.2%).     

The relative importance of temperature and isotope effects on the dipole oscillator strength distribution of H2

Summary The calculation of the effects of temperature and isotopic composition on the energy weighted moments of the dipole oscillator strength distribution of H₂ in the random phase approximation to the polarization propagator are reported. It is seen that the effect of isotopic composition is small, while that of temperature is of an order accessible to experiment. We find that all the mean excitation energiesI , for =–1, 0, 1, decrease with temperature as does the dipole oscillator strength momentS() for >0, while the opposite is true for <0. These effects are interpreted in terms of the bond length dependence of the excitation energies.     

Periodic solutions of dry friction problems

Dry friction problems lead to discontinuous differential equations, e.g. to