Home – Home – Jornals – Chemistry for Sustainable Development 2015 number 3

A brief review dealing with the application of ionic liquids as potential reaction media and catalytic systems in the synthesis of polymers is presented. The best known directions of polymer synthesis with the use of ionic liquids are described. Advantages of polymerization in ionic liquids in comparison with conventional solvents are demonstrated: high polymer yield, improved characteristics of polymers, simplicity of polymer isolation from the reaction medium.

Results of the studies of thermolysis products of black coal from the Tavantolgoy deposit (Mongolia) are reported: the solid residue from thermal decomposition of coal, tarry fraction, liquid condensate of sublimates and the organic fraction isolated from the condensate.

Technology of processing the industrial wastes from the production of linear polyethylene obtained through the liquid-phase polymerization technology in the presence of Ziegler-Natta catalysts was developed. The technology implies separation of wastes by centrifuging and simple distillation centrifugate leading to the low molecular mass polyethylene, low-boiling hydrocarbon fraction (130–210 °C) and the bottoms. The major technological characteristics and application areas for the products of waste processing were established.

Rare zeolite levynite was obtained for the first time on the basis of natural minerals halloysite, obsidian and dolomite. The mineral was studied using derivatographic, X-ray phase, X-ray spectral and electron microscopic analysis methods. Dehydration-rehydration and cation exchange characteristics were studied; the oxygen volume of the resulting product was calculated.

The structural-group composition of natural petroleum emulsifying agents was studied. It is shown that an increase in water content in emulsions causes a substantial increase in the fraction of pyrobitumen in the interfacial layer and a decrease in the concentration of tarry components. It was established that among n- alkanes of the interfacial layers of emulsions with demineralized and oil field water, the fraction of low- and high molecular mass n- alkanes increases.

Features of pyrometallurgical processing of rare metal, practically undressable ores from the Chuktukon deposit (Krasnoyarsk Territory) are considered. It is proposed to use deep reductive melting of ore with brown coal as a reducing agent for rare earth metal (REM) concentrating. During reductive melting, the separation of the melt into the metal part and foamed silicate enriched with REM was carried out. The distribution of iron, manganese, niobium, titanium and REM in the metal and slag parts of the melt was analyzed. The features in the behaviour of iron during reductive melting were marked. It was shown that enrichment of the silicate part of the melt with rare earth metal oxides occurs in complete agreement with thermodynamic calculations. A correlation of lanthanum with cerium and neodymium was analyzed using the TM-3000 electron microscope, by means of mapping. The formed lanthanum-cerium associates (nuclei) are observed both in the vitreous phase and in foamed material (foamed silicate) as separate phases. The possibility of leaching rare earth metals with a weak solution of sulfuric acid was demonstrated; leaching becomes complicated due to the formation of silicic acid gel.

Mechanochemical and ceramic synthesis of calcium molybdate from calcium hydroxide and ammonium heptamolybdate were studied. It was established that CaMoO₄ is formed in the mechanochemcial synthesis; it does not require further thermal treatment. The use of ceramic method requires baking at a temperature of 650 °C.

Sorption of indium, iron (III) and zinc ions from multicomponent solutions within a broad range of acidity (4-500 g/dm³ H₂SO₄) on weakly acidic cationites with functional groups Purolite S955 (diphosphonic (-PO₃H₂) ₂, sulphonic (-SO₃H), carboxylic (-СООН)), Lewatit TP260 (CH₆NO₃P - aminomethylphosphonic), Lewatit TP272 (bis-(2,4,4)trimethylpentylphosphinic - C₁₆H₃₅O₂P) was studied. It was established that the sorption value for indium and iron (III) ions is always high (88-99 %), the degree of zinc ion recovery (4-350 g/dm³ H₂SO₄) decreases within the ranges 87.0-2.0 % (S955) and 56.0-0.1 % (TP260), while iron (II) ions (4-150 g/dm³ H₂SO₄) - from ~100 to ~50 %. From the multicomponent solution (C₀ = 4.4 mmol/dm³; 100 g/dm³ Н₂SO₄; L/S = 8; t = 25 min), indium is best separated from iron (D_р = 2.8) and zinc (D_р = 7.2) on Purolite S955 ionite - recovery degree reaches 95 %. Due to this, weakly acidic cationite Purolite S955 can be used for selective isolation of indium by sorption from acidic solutions from leaching of zinc concentrates.

Zinc extraction from hydrochloric solutions by trialkylphosphine oxide (TAPO) in toluene was studied. It is demonstrated that the dependence of zinc extraction into organic phase on the concentration of hydrochloric acid has an extreme: an increase in zinc extraction with an increase in acid concentration is due to an increase in the fraction of extractable zinc chloro complexes, while a decrease is due to the competitive effect of hydrochloric acid. The compositions of extracted compounds were determined: for the low concentration of hydrochloric acid (≤1.35 mol/L), zinc is extracted into the organic phase in the form of neutral molecules of zinc chloride having the composition [ZnCl₂ × 2TAPO], while with an increase in acidity it is extracted in the form of complex metal halide acids like HZnCl₃ and H₂ZnCl₄. Because of high zinc distribution coefficients, its re-extracted with water is strongly hindered. The introduction of para-tert- butylphenol (AP) into the organic phase containing TAPO simplifies zinc re-extraction and creates prerequisites for the development of extraction-based technological flowsheet allowing efficient recovery of zinc and its separation from admixtures (Fe, Cu, Mn и Pb), including reagent concentrations, flows of aqueous and organic phases, number of extraction steps. The coefficient of zinc separation from the major admixture (iron) is β_Zn/Fe = 15-25. The flowsheet includes zinc extraction with a mixture of TAPO and alkylphenol, removal of admixtures by washing the extract with diluted hydrochloric acid (~0.5 mol/L) and zinc re-extraction with water. Further zinc concentrating and its conversion into sulphate solution are carried out with the help of extraction with di(2-ethylhexyl)phosphoric acid (D2EHPA). The high degree of zinc recovery (~99 %) is achieved after only 11-13 extraction steps. The developed process may be used for efficient isolation of zinc from chloride and chloride-sulphate solutions from leaching zinc ores and concentrates.

It is demonstrated that the structure of tar of the natural bitumen from the Ashalcha deposit (Tatarstan). The composition of these fragments was studied using chemical destruction, liquid adsorption chromatography and gas chromatography-mass spectrometry. It was established that the ether and sulphide bridges in the molecules of tar in bitumen from the Ashalcha deposit bind bind normal and branched alkanes, alkyl cyclopentanes and alkyl cyclohexanes, phenyl alkanes with different positions of phenyl substituent, mono-, di-, tri- and tetraalkyl benzenes, alkyl substituted naphthalenes and phenanthrenes, benzo- and dibenzothiophenes, aliphatic acids and esters, cyclic alcohols and bicyclic terpenoid sulphides. Binding between saturated and aromatic hydrocarbons, dibenzothiophenes, sulphides and aliphatic acids is realized through ether and sulphide bridges. Aliphatic ethers are bound only by sulphide bridges, while cyclic alcohols are bound only by ether bridges. Among the identified compounds, predominant are saturated hydrocarbons, mainly normal alkanes. The presence of С₂₀ and higher hydrocarbons is the evidence that long aliphatic chains are present in the structure of tarry substances in Achalcha bitumen. Among aromatic hydrocarbons, dominating are n- alkylbenzenes, naphthalenes and phenanthrenes, while among heteroatomic compounds alkyldibenzothiophenes are prevailing.

Thermodynamic and kinetic foundations of the interaction between components in the system CuSO₄–Na₂CO₃–WO₃ in the heterogeneous medium were studied. On the basis of the data obtained, a method of the synthesis of copper (II) tungstate with the high yield of the target product was developed. This method is optimized in comparison with the known versions of solid-phase synthesis of CuWO₄.

New Pd-catalysts based on fiberglass materials were prepared, characterized and tested in the selective hydrogenation of acetylene. In spite of extremely low palladium content, the catalysts exhibit high activity and selectivity due to the ability of glass to stabilize fine dispersed Pd particles 1 nm in size in the surface layers and to adsorb selectively only readily polarizable molecules (acetylene), in spite of the large excess of ethylene. As a result, when complete conversion of acetylene is achieved, an increase in ethylene reaches almost 60 %, which exceeds the selectivity of modern industrial catalysts.

The effect of inhibitor additives of different chemical nature on the composition of paraffin deposits of gas condensate at the Urengoy field was determined. It was established that the most efficient additives are those based on polyalkylmetacrylates. The use of highly efficient additives leads to concentrating high-molecular paraffin hydrocarbons and to a decrease in the fraction of naphthene aromatic hydrocarbons in the deposits.

The Decade of Education for Sustainable Development declared by the United Nations Organization came to the end in 2014. Preliminary results of the Decade are presented in the paper. The work that was carried out during the Decade at the Institute of Chemistry and the Problems of Sustainable Development, of D. Mendeleev University of Chemical Technology of Russia is described.