Chemistry. Ecology. Biotechnology – 2015

УДК 543

O.I. Bakhireva, D.A. Popov

SORPTION OF СD2+ IONS BY EXFOLIATED

VERMICULITE IN CONDITIONS

OF MICROORGANISMS FUNCTIONING

Perm National Research Polytechnic University

Nowadays there is a topical problem of treating wastewater from non-ferrous metallurgy and chemical industries, as well as remediation of soils and groundwater contaminated by waste rock ores often containing a wide variety of harmful components. One of the most efficient methods of water treatment is ionic exchange based on using different ionicexchange materials (natural and synthetic). Natural materials are cheap, available in the necessary amounts and innoxious. An example of natural sorbents is exfoliated vermiculite that refers to hydromica group and can be represented by approximate chemical formula R+R+2|AlSi3O10||OH|2 R+ means monovalent cations like potassium or lithium, R+2 – bivalent cations like magnesium, iron, calcium, manganese and etc. Exfoliating of vermiculite is a process of its calcination at about 900oC, which produces a tenfold increase of its volume and significant increase of specific surface area.

On the other hand, there is an important modern technology of removing heavy metals from water – biosorption that means using living organisms or their parts as sorbents. Microorganisms are able to accumulate high amounts of different ions from water.

We obtained a culture of microorganisms able to survive and grow into the nutrient contaminated by heavy metal ions and remove cadmium ions from solutions. Moreover, it was discovered that exfoliated vermiculite has a good adsorption ability in relation to cadmium ions, which was proved by proved by static and dynamic experiments in adsorption columns. Maximum adsorption capacity of vermiculite in relation to Cd2+ is 33.91 mg/g.

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It was found that microorganisms can form a biofilm on vermiculite surface, which noticeably affects its sorption properties. For evaluation of those effects the series of sequent experiments were made. It was sequent periodic microorganism immobilization on vermiculite, then cadmium adsorption, and then desorption. Sorption capacity in relation to microbial biomass and cadmium ions in each cycle was estimated. Immobilization of microbes was realized by irrigation of vermiculite with cultural solution; variation of the eluate’s optical density was measured. After calculating residual microbial concentration in mg/l, sorption output diagrams were plotted and maximal sorption capacities were estimated. Then, cadmium solution (50 mg/l) was filtered through vermiculite with microbes layer, sorption output diagrams were plotted, too. Finally, columns were regenerated by irrigation with 0.1 N nitric acid solution and distillated water. After that, process was repeated. Some cycles were made, results are shown in Table.

Properties of vermiculite sorbent in some working cycles

Those results show that vermiculite capacity in relation to Cd2+ increases from cycle to cycle, which is probably associated with growth of active biofilm on the surface. The first cycle compared with clean vermiculite without biofilm grants 15.6 % of additional capacity, the second 20.7 %, while the third only 4.4 %. Those sequences can be associated with the beginning of dense film formation which blocks ions transfer to the sorption sites. It is proved by biomass capacity data – it decreased from cycle to cycle when regeneration method was the same. The biofilm became more dense and stable. Further changes of vermiculite properties will be discovered by more cycles of cadmium adsorption.

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УДК 544

E.E. Alikina, E.A. Kasatkina, I.A. Permyakova. V.V. Vol’khin

THE DETERMINATION

OF GLYCEROL IN BIODIESEL

Perm National Research Polytechnic University

Biodiesel is the fuel made from vegetable and animal oil. Biodiesel is a methyl or ethyl esters of fatty acids produced by the interesterification reaction.

Furthermore, glycerol is one of the reaction byproducts. The amount of glycerol in biodiesel according to the European standard EN 14214 must not exceed 0.25 wt. %.

It is important to choose the right method for determining the content of glycerol in biodiesel. The method (Keppy N.K., Bain G., Allen M.W.) was used for determination of free glycerol in biodiesel, it is based on the interaction of glycerol with sodium periodate. Sodium periodate reacts with free glycerol in the sample to generate formaldehyde. Reaction between this formaldehyde and acetyl acetone produces the yellow complex, 3,5-diacetyl-1,4-dihydrolutidine. This yellow compound exhibits a maximum absorbance peak at 410 nm, where its concentration in the sample is measured.

However, experiments made by these methods have not yielded the required results because formaldehyde is an intermediate product of the interaction of glycerol with sodium periodate. Additional experiments were conducted to clarify the conditions of interaction of formaldehyde with acetylacetone. According to the Russian National Standard GOST R 55227-2012 formaldehyde interacts with acetylacetone in the Ammonium acetate stock solution. The stage with use of the Ammonium acetate stock solution was added into the method for the determination of glycerol in the biodiesel. The obtained results were satisfactory.

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The spectrophotometric analyses were carried out using the Unico 1201 spectrophotometer.

The calibration curve characterizes dependence of the absorbance at 410 nm against concentration of glycerol and the calculated R2 is 0.96. The control measurement of the content of glycerol in the sample showed the result of 9.48 mg/kg, with a relative deviation to 5.28 %.

УДК 541.183.12

A.U. Druk, D.А. Rozhina, А.S. Makoveev, S.U. Solodnikov, L.S. Pan

USING COMPOSITE MATERIALS BASED

ON SEA ALGAE AND HEXACYANOFERRATE

OF FERRUM AS ENTEROSORBENTS

Perm National Research Polytechnic University

Threats of the environmental pollution with radio nucleus have appeared with the development of nuclear energy, recycling of radio nucleus, accidents at the nuclear power plant and etc. Enterosorbents can be used in weakening the effects of ionizing radiation on human organism. They are used for prevention and treatment of radiation sickness. Enterosorbents bind exoand endogenous substances in digestive tract by adsorption, absorption, ion exchange and complex formation.

“Ferrotsin” is one of the most important pharmaceuticals, which was created on the basis of the iron ferrocyanide and can be used to bind radionuclides. “Ferrotsin” binds radioactive isotopes of cesium, rubidium and thallium in intestines, which accelerates their removal from an organism.

However, the known enterosorbents have many imperfections. Some toxic effects and limited duration of their protective action have initiated the research of biological nontoxic substances with radio protective properties. The ability of algae’s carrageenan and alginate to form salts with metals helps to use it as nontoxic and chelating agents in treat-

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ment of poisoning by heavy metals. Therefore, in this research the brown algae of the Black Sea Zostera Marina were investigated as a biological object with a radionuclide sorption ability.

To produce enterosorbents based on the sea algae's biomass they were processed by salt solutions of iron (III) ferrocyanide and (II) potassium. To avoid co-precipitation of iron hydroxide the sorbent was washed with hydrochloric acid in the final stage. Thus, on the algae surface the phase of iron ferrocyanide H0,6К0,2Fe1,07[Fe(CN)6] deposited.

The obtained biosorbents were tested on a series of 6 rats. Rats were exposed to certain amounts of cesium and the sorbent and then during the day urine and feces samples were analyzed for cesium.

It is shown that a major amount of cesium is taken out by urine (70 %) and feces (6 %). Low content of cesium in feces can be explained by a small amount of the introduced sorbent (0.03 g). For a complete determination of cesium it is necessary to analyze urine and feces samples in the second and third day. It is established that biosorbents based on sea algae have a better sorption ability per mmol of ferrocyanide component, than pure iron ferrocyanide.

УДК 579.66

L.N. Smirnova, O.N. Oktyabrskiy *

DEVELOPMENT OF A TEST SYSTEM FOR CONTROL OVER THE CONTENT OF HEAVY METALS IN NATURAL AND MAN-MADE WATERS.

Perm National Research Polytechnic University

* FGBUN Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences, Perm

One of the sources of water pollution are waste water factories, they comprise dilute solutions of heavy metals. Pollution leads to deterioration of water quality and habitat conditions in violation of these aquatic organisms. In the past decade an increasing interest in the use of microorgan-

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isms as test systems for the evaluation of environmental pollution. It is known that microorganisms may exist as free-floating planktonic cells and in the form of biofilms, which is characteristic of virulence increased resistance to antibiotics and other antimicrobial agents. Less is known about the stability of the biofilm to the salts of heavy metals.

In this work we studied the effect of ions cobalt, iron, nickel and zinc on biofilm formation by bacteria. As microbial test systems used bacterial strain E. coli BW25113 (wild-type). Bacteria were grown on mineral medium, M-9, with the addition of 0.4 % glucose, 0.2 % casamino acids and 10 g / ml thiamine on immunological plates at 37 °C. The culture was incubated without shaking for 22 hours and measured for absorbance planktonic culture (OD600) using a microplate spectrophotometer xMarkTM Bio-Rad. Biofilm were painted 0.1 % solution crystal violet after removal of plankton, washed from excess of dye, extracted 96 % alcohol and absorbance was measured at 540 nm. Specific biofilm forma-

tion was determined by dividing the OD540 to OD600.

At concentrations ranging from 1 μM to 10 cobalt sulfate, nickel sulfate and zinc sulfate had no significant effect on cell growth in plankton, while the iron sulphate induced a 17 % stimulation of growth. To eliminate the effect on bacteria sulfate anion, experiments were conducted in the presence of sodium sulfate. Shown that the sulfate anion has no significant effect on the growing culture.

At a concentration of 10 μM both salts (CoSO4 × 7H2O and FeSO4 × 7H2O) decreased the biofilm formation by 18 and 27 %, respectively. Thus specific biofilm formation in case of sulfate of iron decreased by 23 %. Thus, the tested saltse specially iron sulphate, can significantly inhibit the formation of biofilms grown on mineral medium and to stimulate plankton growth in culture. Our results show that the formation of microbial biofilms is sensitive to heavy metals and can serve as a basis for the creation of test systems for the evaluation of environmental pollution.

This work was supported by the grant of RFBR-Ural № 14-04-96031.

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УДК 544.034

A.V. Tsukanov, D.A. Kazakov, V.V. Vol’khin

PREPARATION OF MAGNETIC CATALYSTS FOR BIOCATALYTIC AND CHEMICAL SYNTHESIS

OF GLUCONIC ACID

Perm National Research Polytechnic University

Gluconic acid and its salts are important materials for pharmaceutical, food and textile industries. There are different approaches for the production of gluconic acid: chemical, electrochemical and biochemical. Biochemical and chemical methods are considered to be the most promising. Biochemical method is based on the use of glucose oxidase. This enzyme catalyzes the oxidation of glucose by oxygen. Application of free (not immobilized on the carrier) glucose oxidase for oxidation of glucose is not desirable because the purified enzymes are expensive and there is no possibility of re-using the enzyme. That is why obtaining biocatalysts based on immobilized microbial cells is a promising research avenue. For chemical oxidation of glucose solid catalysts based on supported palladium are used. After chemical or biocatalytic glucose oxidation fine catalysts particles must be removed from the aqueous phase. This stage complicates oxidation process. A feasible approach to solve this problem is development of magnetic catalysts which can be easily removed from the aqueous phase by magnetic separation. The aim of this study is to obtain magnetic catalysts for biocatalytic and chemical synthesis of gluconic acid. The objectives of the study are 1) isolation of microorganisms producing glucose oxydase, study of growth kinetics and glucose oxidase activity of isolated culture; 2) preparation of magnetic carrier for catalysts of chemical and biochemical oxidation of glucose; 3) preparation of biocatalyst by immobilization of microorganisms producing glucose oxidase on the magnetic carrier, study of the catalytic activity of the biocatalyst obtained; 4) preparation of magnetic Pd – containing catalyst for chemi-

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cal oxidation of glucose, the study of its catalytic activity; 5) comparative evaluation of prepared catalysts for biochemical and chemical oxidation of glucose.

A culture of fungi producing glucose oxidase was isolated. Isolated culture was identified as Penicillum. Magnetic solid carrier (fine composite particles with a core of magnetite (Fe3O4) and a shell of silica (SiO2)) for catalysts of chemical and biochemical oxidation of glucose was prepared. Using the prepared carrier, magnetic Pd – containing catalyst (Pd/SiO2/Fe3O4) for chemical oxidation of glucose was obtained. The effect of hydrodynamic conditions on the rate of glucose oxidation in the presence of catalyst Pd/SiO2/Fe3O4 was studied (table).

The effect of hydrodynamic conditions on the rate

of glucose oxidation in the presence of catalyst Pd/SiO2/Fe3O4 (catalyst concentration of 1 g/l)

It can be seen (table) that the rate of catalytic glucose oxidation increases with the growth of mixing rate of the liquid phase. These data indicate that the process is implemented in the diffusion mode.

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УДК 544.478-03

J.O. Gulenova, D.A. Kazakov, V.V. Vol’khin

OXIDATIVE MINERALIZATION OF 4-NITROPHENOL USING BIODEGRADATION AND CATALYTIC OZONATION

Perm National Research Polytechnic University

Concentration of nitrophenols in water in accordance with ecological norms should be between 0.002–0.300 mg/l, therefore pollution of environment by nitrophenols should be reduced as much as possible. Biodegradation of nitrophenols is slow because of their toxicity for microorganisms. It is known that the rate of biodegradation of toxic organic compounds can be increased by their pretreatment with strong oxidants. Fenton's reagent, hydrogen peroxide, UV – irradiation or ozone can be used as an oxidizing agent. One of the most promising methods for oxidative treatment of wastewater containing nitrophenol is ozonation. The catalysts can be used to improve the efficiency of ozonation. However, the effect of oxidative pretreatment with ozone on nitrophenols biodegradation rate was not investigated enough. Effectiveness of catalysts for nitrophenols mineralization with ozone was not enough studied too. The aim of this study is to investigate mineralization of 4-nitrophenol (4-NP) by biodegradation, non-catalytic and catalytic ozonation and biodegradation combined with oxidative pretreatment by ozone, comparative evaluation of these processes and selection of process for technology of wastewater purification from 4-NP.

Kinetics of 4-NP biodegradation was studied. It was shown that 4-NP biodegradation is more intensive under its low concentrations (less than 0.139 g/l). Increasing the concentration of 4-NP inhibits the growth of microorganisms and slows down the biodegradation process. Kinetics of non-catalytic mineralization of 4-NP during ozonation was studied. It was shown that the rate of 4-NP mineralization at non-catalytic ozona-

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tion depended on pH, temperature and initial concentration of 4-NP. Magnetic catalysts (fine composite particles with a core of magnetite (Fe3O4), and a shell of titanium dioxide (TiO2)) for 4-NP mineralization with ozone were prepared. The influence of obtained catalyst on the rate of organic carbon mineralization with ozone was studied (Table 1). It can be seen that catalyst TiO2(amorphous)/Fe3O4 increases the effective rate constant of organic carbon mineralization by a factor of 1.6.

Table 1 The influence of magnetic catalysts on effective rate constant (keff)

of 4-NP mineralization with ozone (catalyst concentration of 1,2 g/l, temperature 30 °C)

The catalyst TiO2(anatase)/Fe3O4 is not effective. It can be explained by a significant reduction in the specific surface area and the concentration of surface OH – groups during the heat treatment (600 °C) used for preparation of the catalyst. The optimal composition of catalyst TiO2(amorphous)/Fe3O4 was found. This composition corresponds to magnetite content of 30 % (wt.). It was shown that increased catalyst (TiO2(amorphous)/Fe3O4) concentration led to growth of 4-NP mineralization rate (Table 2).

Table 2

The influence of catalyst (TiO2 (amorphous)/Fe3O4) concentration on effective rate constant (keff) of 4-NP mineralization (30 °C)

It was found that mineralization of 4-NP in the presence of catalyst TiO2(amorphous)/Fe3O4 was more rapid in alkaline medium (pH 10).

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