Utilization of α-olefins obtained by pyrolysis of waste high density polyethylene to synthesize α-olefin-succinic-anhydride based cold flow improvers

A new route of utilization of α-olefin rich hydrocarbon fractions obtained by waste polymer pyrolysis was investigated. α-olefin-succinic-anhydride intermediate-based pour point depressant additives for diesel fuel were synthesized, in which reactions needed α-olefins were obtained by pyrolysis of waste high-density polyethylene (HDPE). Fraction of α-olefins was produced by the de-polymerization of plastic waste in a tube reactor at 500℃ in the absence of catalysts and air. C_17~22 range of mixtures of olefins and paraffins were separated for synthesis and then, these hydrocarbons were reacted with maleic-anhydride (MA) for formation of α-olefin-succinic-anhydride intermediates. The olefin-rich hydrocarbon fraction contained approximately 60% of olefins, including 90%~95% α-olefins. Other intermediates were produced in the same way by using commercial C₂₀ α-olefin instead of C_17~22 olefin mixture. The two different experimental intermediates with number average molecular weights of 1850g/mol and 1760g/mol were reacted with different alcohols: 1-butanol, 1-hexanol, 1-octanol, i-butanol, and c-hexanol to produce their ester derivatives. The synthesized ten experimental pour point depressants were added in different concentrations to conventional diesel fuel, which had no other additive content before. The structure and efficiency of experimental additives were followed by different standardized and non-standardized methods. Results showed that the experimental additives on the basis of the product of waste pyrolysis were able to decrease not only the pour but also the cloud point and cold filter plugging point (CFPP) of diesel fuel, whose effects could be observed even if the concentration of additives was low. Furthermore, all additives had anti-wear and anti-friction effects in diesel fuel.     

An alternating direction scheme on a nonuniform mesh for reaction-diffusion parabolic problems

In this paper we develop a numerical method for two-dimensionaltime-dependent reaction-diffusion problems. This method, whichcan immediately be generalized to higher dimensions, is shownto be uniformly convergent with respect to the diffusion problems.This method, which can immediately be generalized to higherdimensions, is shown to be uniformly convergent with respectto the diffusion parameter.     

X-ray fluorescence determination of As, Bi, Co, Cu, Fe, Ni, Pb, Se, V and Zn in natural water and soil extracts after preconcentration of their pyrrolidinedithiocarbamates on cellulose filters

A simple method for the elements preconcentration on thin-layer paraffin-treated cellulose filters was proposed. It was found that pyrrolydinedithiocarbamates of As(III), Bi, Cd, Co, Cu, Fe(III), Ni, Pb, Se(IV), V(V) and Zn obtained after mixing of sample (3-5 ml min⁻¹) and reagent (0.7-1.0 ml min⁻¹) streams were quantitatively recovered from 100 ml sample. The sample acidity was adjusted to pH 4.8-5.2 for preconcentration of Cd, Co, Cu, Fe(III), Ni, Pb, V(V) and Zn, and to 2 M HCl for preconcentration of As, Bi and Se. The optimum reagent concentration was found to be 0.1%. The elements were determined on the filters by X-ray fluorescence spectrometry. The detection limits achieved were 0.1-4.0 μg of element on the filter. Relative standard deviation (R.S.D.) was not higher than 0.08 while determining 5-50 μg of elements on filter. Accuracy and precision of the technique proposed were evaluated by the analysis of spiked natural samples.     

Gradient HPLC Separation of Alkylphosphonic Acids on a Hypercarb Porous Graphitic Carbon Adsorbent with an Aqueous Formic Acid Solution as the Mobile Phase

An approach to the gradient HPLC separation of alkylphosphonic acids on a Hypercarb porous graphitic carbon adsorbent with an aqueous formic acid solution as a mobile phase is proposed. Analytes were detected using a quadrupole mass spectrometer. To increase the retention of the analytes, the chromatographic column was washed with water before the injection of a sample solution. This procedure results in a three- to fourfold increase in the retention factors of alkylphosphonic acids in comparison with the analogs described in the publications.     

Synthesis and Study of the Properties of Magnetic Adsorbents Based on Hydrophobized Silica

Moscow University Chemistry Bulletin - We proposed a method for producing magnetic nanocomposite adsorbents, based on the adsorption of Fe3O4 magnetic nanoparticles (MNPs) on hydrophobized silicas...     

Crucible atomizer for determining dissolved and suspended forms of elements in natural waters

A model of a specialized microcolumn has been proposed and tested, namely, a crucible atomization microcolumn for electrothermal atomic absorption analysis of natural waters in which the zone of isolation of suspended matter and the zone of dynamic preconcentration of dissolved forms of elements are separated. A direct independent analysis of solid suspended matter and DETATA concentrate is possible upon completion of preconcentration. Such an approach is used to determine suspended and dissolved forms of cadmium and lead in river water and soil groundwater.     

X-ray fluorescence determination of lanthanum,cerium, praseodymium,and neodymium in technological solutions after preconcentration on DETATA cellulose filters

Sorption of some rare earth elements on filters with immobilized diethylenetriaminetetraacetate (DETATA) groups was studied. It was shown that the elements are quantitatively extracted from solutions with volume of 20–500 mL at pH values ranging between 3.5 and 5.5 and a flow rate from 1 to 8 mL/min. It was proposed to use masking agents such as sulfosalicylic acid and 1,10-phenanthroline for extracting elements from iron-containing solutions. The elements were determined directly on filters by X-ray fluorescence spectroscopy. The calibration dependences were shown to be linear in the concentration range from 2 to 100 μg of rare earth element per filter. The limits of detection of La, Ce, Pr, and Nd calculated on the basis of the 3s criterion in the case of extraction from 100 mL solutions were 0.03, 0.03, 0.01 and 0.01 μg/mL, respectively.     

Methods of the preconcentration of trace components: Development in Russia (1991–2010)

The main achievements of Russian scientists in recent decades in the fields of adsorption, solvent extraction, and other methods of the analytical preconcentration of inorganic and organic microcomponents are presented.