Home – Home – Jornals – Chemistry for Sustainable Development 2003 number 6

Perspective directions and results of the investigations of physicochemical transformations undergone by mineral and organic components of soil and natural water in the presence of heavy metal ions, which are among the most widespread pollutants of the biosphere, are considered. The mechanism of the indicated processes is discussed along with the effect of various factors on their kinetics (nature of heavy metals and substrate, pH of the medium, action of solar radiation, etc.).

Simple halogenated alkanes and their derivatives comprise relatively large group of natural compounds which were discovered in cyanobacteria, algae, phytoplankton, fungi and plants. The structures of more than 100 compounds are considered.

Halogenated complex phenols comprise several small groups of natural compounds. These compounds were detected in microorganisms, cyanobacteria, algae and invertebrates. The structures of about 150 compounds are considered and the data on their biological activity are reported.

A homopolymer of N,N'-bis(vinyloxyethyl)thiuramdisulphide was synthesized via cationic polymerization and investigated as a sorbent of the ions of mercury and precious metals. The effect of the nature and concentration of acid, phase contact time on the extraction of metals was revealed; sorption capacities of the polymer and metal partition coefficients were estimated. It was shown that the sorbent exhibits high sorption activity to metal ions in the cationic form: with respect to mercury (Hg²⁺) from 1 M HNO₃ solution - 1100 mg/g, 1M H₂SO₄ - 990 mg/g, 1 M HCl - 280 mg/g; with respect to silver (Ag⁺) from 1 M HNO₃ - 850 mg/g, from 1 M H₂SO₄ - 900 mg/g. A mechanism of the interaction of active groups of the sorbent with metal ions was proposed on the basis of IR spectroscopic data. The homopolymer of N,N'-bis(vinyloxyethyl)thiuramdisulphide sorbs mercury and silver ions selectively from a mixture of copper, nickel, iron and zinc salts. The possibility to use the sorbent for concentrating precious metals and for analytical purposes was demonstrated. A method of sorbent regeneration was developed.

Concentrations of 23 polycyclic aromatic hydrocarbons (PAH) were determined in the bottom sediments of the tributaries: the Selenga, the Turka, the Khaym, the Barguzin, which provide more than 70 % of the water drainage into the Baikal, and in the bottom sediments of the shallow water regions of the lake: the Zmeevaya bay (Chivyrkuy arm) and the Sor-Cherkalovo bay. It was discovered that the level of pollution with PAH is relatively low; the sum of PAH concentrations for the 23 individual compounds is within the range 1.4-5.2 mg/kg (for 5 compounds, the range is 0.15-1.11 mg/kg). The presence of PAH in the samples of bottom sediments is due to local sources of petrogenic and pyrolytic nature.

Chlorination of butyl rubber by molecular chlorine in solution relates to the class of fast chemical reactions. A new continuous method of obtaining chlorobutyl rubber in the industry is proposed on the basis of small-size tubular turbulent devices of the jet type; the method provides many ecological and technological advantages.

The problems concerning the application of natural zeolite of the Khonguruu deposit (Yakutia) to the sorption purification of oil-containing waste water are considered. Physicochemical and sorption properties of the zeolite are described. It is shown that khongurin can be used for the extraction of both molecularly dissolved and emulsified oil products. The curves of filtration of oil-containing natural sorbent are reported. The application of khongurin in water preparation processes and in waste water purification from oil products seems to be reasonable because of its large resources and low cost.

The experimental data are presented describing the processes of briquetted and granular smokeless fuels production from lignite with the use of heated die and cheap biobinders. The influence of moisture and bio-binder content, pressure, temperature, time of process on the properties of resulting fuels was studied. Briquettes and granules with calorific value 24-27 MJ/kg and with good mechanical properties were produced at the selected process parameters. They can be used  as smokeless fuels and reducing agents.

It is demonstrated experimentally that the application of freezing - unfreezing procedure for the purification of water from soluble amounts of CaCO₃ under the conditions recommended for obtaining water from melted ice (freezing ~0.2 l of water at -17 ^oC) is ineffective. An explanation is the fact that salt freezes into the ice. It is concluded that changes in the concentrations of inorganic impurities cannot be a decisive physicochemical factor for distinguishing between the melted water and the initial one.

On the basis of simultaneous gamma spectroscopic determination of radionuclides of the uranium series (²³⁸U, ²²⁶Ra, ²²²Rn, ²¹⁰Pb) and isotopes arriving from the atmosphere (²¹⁰Pb_atm and ¹³⁷Cs) in rocks and bottom sediments, radiogeochemical background of land sediments represented mainly by granitoid weathering products was obtained (35-55 Bq/kg), along with evidences of the hydrodynamic mode of sediment formation within the recent century. Three types of radioactivity anomalies exceeding the background by one-two orders of magnitude were revealed on the southern bank of the lake: natural uranium and radium anomalies; industry-related radium anomalies (ash obtained from burning uranium-bearing coal); industry-related uranium anomalies. Sedimentation rate was estimated in the deep water region using the decay of ²¹⁰Pb_atm activity to be 0.2-0.4 mm/year during the recent century. On the basis of uranium to radium ratio, it was established that the fraction of uranium in deep water sediments arriving from the lake water is 1.5-2 times higher than the fraction arriving with the suspension. One of the sources of uranium in the lake water was erosion of uranium-bearing coal within the geological time scale. A layer enriched with radium was discovered near the bank at the depth of 5 to 20 cm. The presence of high-temperature mineral mullite in the sediment is an evidence of the penetration of industry-related radioactive ash into the lake in amounts that can hardly be dangerous for the biogeosystem of the lake Ysyk-Kul.

The state of surface waters, which are polluted with the waste of the lead-zinc enriching factory in Salair city (Kemerovo Region), is described. The total salt composition, total content of elements and their distribution in surface water downstream the river, in suspension and bottom sediments, and also the amount and fractions of mobile forms are studied. It is noted that Zn, Cd migrate in water generally in the truly dissolved form, Ba, Fe, Pb in the sorbed one, Cu, As are distributed approximately equally between these forms. It is shown that the elements are accumulated and fixed in bottom sediments, but they can become a cause of secondary pollution with the acidification of the medium. For the given region, the metals Ba, Zn, Cu, Cd are the most dangerous ones in the ecological aspect.

The results of experimental work on lead extraction with nitric solutions of Fe(NO₃)₃ from PbS lead concentrate after its mechanical activation are reported.

Hydrogen for the needs of industry is obtained by thermo-chemical transformation of the natural hydrogen-containing raw material - coal, natural gas, biomass - at high temperature or by electrolysis of water. A large number of works has been published indicating that hydrogen has not been consumed yet as a free element of the Earth; its outflow to the Earth's surface goes on. Gas accumulations containing from 10 to 50 % of hydrogen by volume have been discovered. It may be assumed that hydrogen still can be the major gas component at a definite depth; however, due to its high reactivity it reacts with oxygen and carbon to form water, and also hydrogenates carbon inclusions to form hydrocarbon fluids. Because of this, hydrogen outflow in the free state to the Earth's surface cannot be intensive. In the present review, an attempt is made to estimate the strategic, technological and economical reasonableness of search, production and concentrating natural hydrogen, as well as ecological advantages of the use of hydrogen of natural origin as the mean to decrease the emission of carbon dioxide.

The distribution of natural radioactive elements (uranium, radium, thorium and potassium) in the soils of the Priobskoye plateau and the eastern part of the Kulunda plain depicting different physical geographical zones is presented. The most evident radiogeochemical zoning is revealed for uranium and potassium in the autonomous landscapes. The concentrations of radium and thorium remain at the same level without any noticeable redistribution. A method is proposed to estimate uranium carry-over during Holocene (12