Chemistry. Ecology. Biotechnology – 2015

The mineralization of 4-NP by biodegradation combined with oxidative pretreatment with ozone was studied. It was shown that pretreatment of water containing 4-NP with ozone reduced the rate of organic carbon mineralization during biodegradation.

УДК 549.755.211

E.L. Nosenko, G.V. Leontjevа, V.V. Vol’khin

LOWERING THE BIOAVAILABILITY OF HEAVY METALS IONS IN CONTAMINATED SOILS USING PHOSPHATE STABILIZERS-AMELIORATORS AND THE RESULT EVALUATION BY BIOTESTING

Perm National Research Polytechnic University

Heavy metals (HM) nowadays have the second highest degree of danger, making room for pesticides and leaving behind the well-known pollutants such as carbon dioxide and sulphur. The pollution by HM is conditioned by their wide use in industrial production. Due to the imperfect systems of cleaning and emergency situations HM are released into the environment, especially the soil and causing major pollution there. The soil is a source of secondary pollution because waters get into the World ocean. From the soil HM are absorbed by plants which then get into the food.

In this work the task is to lower bioavailability of Ni2+ ions in the soil, as typical elements of industrial waste.The magnesiumammoniumphosphate acts as an ameliorator-stabilizer of Ni2+. This compound is not dangerous for the soil. Ions Mg2+, NH4+ and PO43– are used by plants and ground organisms as energy sources and PO43– ions can lower a concentration of free nickel ions, Ni2+, due to the formation of sparingly soluble phosphates.

The X-ray analysis was carried out on samples of MAP and nickel sorption products. From the analysis it was found out that the structure of struvite in nickel sorption remained.

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An analysis of the particle size of the starting materials and sorption products was made by the use of fan automatic device sieving the powders with laser registration. The results show that the particles of magnesiumammoniumphosphate increased at all stages of the process. Such a process should facilitate the absorption of ions Ni2+, while it is shown that nickel salts of anions affect the recrystallization process of phosphate. It can be expected that the anions will affect the sorption of the magnesiumammoniumphosphate ions Ni2+.

A series of samples were made and a study was performed to evaluate the NO3–, Cl–, SO42– anions effects on uptaking MAP ions Ni2+. The experiments confirmed that the adsorption of Ni2+ ions increases in accordance with the sequence of anions Cl-< NO3-< SO42–.

The activity of soil enzymes is a sensitive indicator of the state of soil fertility. The source of the enzymes in the soil are microorganisms and higher plants, therefore, the better the conditions for their lives are, the more enzymes are in the soil. Of all the enzymes the activity of catalase is one of the most sensitive, so its activity can be used as a criterion for assessing recovery functions of soils. Catalase catalyses decomposition of hydrogen peroxide to water and molecular oxygen.

At this stage of the study suppression of the bioavailability of Ni2 + ions through MAP was controlled by the enzymatic activity of the soil. The determination method of catalase activity in the soil is based on measuring the decay rate of hydrogen peroxide during its interaction with the soil according to the volume of evolved oxygen determined by the activity of catalase. On administering 0.5 g MAP/kg in the soil catalase activity increases by 67 %. On administering 0.1 g Ni2+/kg in the soil, catalase activity decreases by 38.1 %. On administering the same dose of MAP contaminated with nickel in the soil catalase activity increased by 23.5 %, meaning that nickel toxicity was not shown; this can be attributed to its stabilization by magnesiumammoniumphosphate.

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УДК 544

A.S. Averkina, V.V. Vol’khin

EFFECTS OF FILMS OF HYDROPHOBIC PARTICLES ON THE TRANSPORT OF OXYGEN THROUGH THE AIR – WATER INTERFACE IN PROCESSES OF BIOCATALYTIC OXIDATION OF GLYCEROL

Perm National Research Polytechnic University

Dust and aerosols are major sources of air and water pollution. Annual emission of these pollutants reaches 1,670 megatons (G. Fellenberg). These pollutants are formed by anthropogenic and natural processes, and have mineral and biogenic origin. Mineral contaminants include particles of dust from the soil, smoke, soot, ash, and finally, polycyclic aromatic hydrocarbons.

Particles exhibiting hydrophobic properties mainly accumulate on the surface of water. They can form their own films and stabilize emulsions or foams, due to being concentrated at water-air or water-oil interfaces.

Hydrophobic particles have a similar effect on the interfacial transport of oxygen during cultivation of aerobic microorganisms and biocatalytic oxidation of organic substances, requiring the constant presence of oxygen in the liquid phase. In this case, we can expect not only a manifestation of a negative effect in the presence of hydrophobic films, but also an acceleration of interfacial transport (if the particles act as a catalyst masstransfer).

When planning the experiment main objectives consisted of determining the effect of particles of silicagel (10 microns); the surface of these particles is hydrophobic due to marked radicals – C16 (Diasorb – 130 – S16T). The considered hydrophobic particles of silicagel form at the interface air-water two-dimensional structures (films), wherein the relationship between the particles has a dynamic character. Experimentally

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(with the optimum frequency mixing at 200 rpm) the values of oxygen masstransfer’s enhancement factor (E) were obtained by adding various electrolytes at a concentration of 2 mmol/l. The results are shown in the table.

Comparison of the area occupied by the particles (S), and values of oxygen masstransfer’s enhancement factor

with added electrolytes

Diasorb – 130 – S16T (10 microns); concentration of electrolyte (C), 2 mmol/l; speed 200 rpm

The results showed that under these conditions, the hydrophobic particles act as an activator of oxygen transport, while the speed of a phase transfer increases in the series: MgCl2 < Na2SO4 < LiCl < NaCl < < RbNO3 < KCl < Cs2SO4. In this series of salt cations play a decisive role: the values of E increase with decreasing energy of hydration of cations, which may be due to the weakening of the strength at the airwater interface.

In order to determine the effects of films of hydrophobic particles on the oxygen masstransfer into the aqueous phase, a process of oxidative biotransformation of glycerol into carboxylic acid was applied. The conditions of cultivation of Aspergillus niger fungi are selected. During cultivation, glucose (carbon source) was replaced by glycerol. Replacing the source did not cause inhibition of growth of the culture, so the inhibitory effect of glycerol on the culture was investigated. Even regardless of the dosage of the substrate, the culture quickly adapted and there was no expressed inhibitory effect. Measurements of the growth were taken using photocolorimeter and pH-meter. The experimental results show the possibility of glycerol biotransformation. The culturing conditions and results of the studies are being evaluated, analyzed and detailed.

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УДК 544.478-03

M.N. Obirina, D.A. Kazakov, V.V. Vol’khin

MINERALIZATION OF OXALIC ACID

BY BIODEGRADATION AND CATALYTIC OZONATION

Perm National Research Polytechnic University

Oxalic acid (OA) is widely used in the chemical, textile and leather industries, as well as in the production of detergents. It leads to intensive pollution of wastewater by OA. The concentration of OA in water in accordance with ecological standards should not exceed 0.5 mg/l. Biodegradation of OA to CO2 and H2O is slow because of its strong acidic properties. Taking into account negative effect of low pH on microorganismsdestructors it can be expected that the rate of OA biodegradation will increase with its decreased concentration in water. Ozonation is considered as one of the most effective ways to reduce OA concentration in wastewater. However, this process is very expensive because it requires large amount of energy. Therefore, to reduce energy consumption for wastewater treatment from OA, ozonation can be applied only as the first stage of the process to reduce the OA concentration to a level acceptable for further biodegradation. The influence of OA concentration decrease by preliminary oxidation with ozone on OA biodegradation rate remains unexplored. It can be assumed that the pre-oxidation of OA with ozone can be intensified by use of catalysts. However, data on the effectiveness of catalysts application for OA mineralization with ozone is not sufficient. The aim of this study is to investigate mineralization of oxalic acid by biodegradation, non-catalytic and catalytic ozonation and biodegradation combined with preliminary ozonation.

Mixed cultures of oxalic-acid-degrading microorganisms from different sources (activated sludge from sewage treatment plant, sludge from river and river water) were isolated. It was shown that the culture isolated from activated sludge degrades OA most intensively. Biodegradation of

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OA is more intensive at low OA concentrations (less than 0.005 M). Increase of OA concentration inhibits the growth of microorganisms and slows down biodegradation.

Kinetics of non-catalytic ozonation of OA was studied. It was shown that the rate of OA mineralization at non-catalytic ozonation depended on pH, temperature and initial concentration of OA.

Investigation of the influence of catalysts (activated carbons BAU-A and AG-3) on OA mineralization rate was carried out. The results are presented in table.

The influence of catalysts (activated carbons) on effective rate constant of OA mineralization (keff)

It can be seen (see table) that mineralization of OA with ozone without catalyst is very slow. Mineralization rate of OA is significantly increased in the presence of activated carbons which act as catalysts. It was shown that catalytic activity of activated carbons grew as specific surface area increases. It was found that the effective rate constant of OA mineralization (keff) increased from 6.5·10–3 min–1 to 18.5·10–3 min–1, with catalyst concentration (AG-3) increasing in the range of 0.2–2.4 g/l. Reducing the particle size of the catalyst (AG-3) leads to significant increase in its catalytic activity.

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УДК 546.46’185

L.I. Ismagzamova, G.V. Leont'yeva

THE DETERMINATION OF SYNTHESIS CONDITIONS

FOR HYDRATE Mg3(PO4)2·22H2O

Perm National Research Polytechnic University

Magnesium forms certain phosphates which are distinguished by composition, properties and structure. The most important of them are Mg3(PO4)2, Mg3(PO4)2·8H2O, Mg3(PO4)2·22H2O and MgHPO4·3H2O. Among them Mg3(PO4)2·22H2O has an increased chemical activity. Only in this phosphate all cations and anions are completely surrounded by molecules H2O, which predetermines the increased lability of this structure. At the same time, the structure of Mg3(PO4)2·22H2O is characterized by metastability, which hampers the synthesis of this super-hydrate.

The task of this investigation is to determine the synthesis conditions of Mg3(PO4)2·22H2O with the minimum admixture of other phases. The phase composition of solid-phase synthesis products is carried out by X-ray analysis. The conventional procedures were used (Method of powder). The morphology of the formed crystals was also controlled. Microphotographs of sediments were obtained with the aid of the optical microscope, connected to a computer via a digital camera.

The results of this investigation showed that interaction of the solutions of 0.1M MgCl2 and 0.1M Na3PO4 in the stoichiometric ratio with pH > 9.5 leads to the formation of Mg3(PO4)2·22H2O. The solution’s temperature is important. A cooling of the solution is preferable. At the temperatures of 25 °C and above it is possible to form more thermodynamically steadier structure of Mg3(PO4)2·8H2O. Maintaining Mg3(PO4)2·22H2O in the mother liquor at room temperature proves to be sufficient for the gradual loss of crystallization water by magnesium phosphate, which can lead to the direct coordination of groups PO43- with the ions Mg2+ in the solid phase. The complete dehydration of crystal hy-

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drate happens when heat-treated of sediment is used. A decrease of pH in the synthesis solution leads to the formation of MgHPO4·3H2O.

The method of freezing was used for the preparation of the granulated sediments of Mg3(PO4)2·22H2O. The suspension of synthesized magnesium phosphate was washed by the method of sequential decantation by the distilled water and maintained in the freezer in the range from –5 to –7 °C during 12 hours. After defrosting the powder with the particle sizes from 80 to 170 micron was obtained, which makes it possible to use it as a sorbent in the column under dynamic conditions.

УДК 549.755.21

A.V. Shutova, G.V. Leont’eva

INFLUENCE OF SURFACTANT ON THE MORPHOLOGY

OF STRUVITE IN ITS PRECIPITATION

FROM AQUEOUS SOLUTIONS

Perm National Research Polytechnic University

Struvite, MgNH4PO4·6H2O, is recommended for use as a soil improver – stabilizer of ions of heavy metals (HM) in soils, aiming at decreasing bioavailability of toxicants for plants. However, soils contain surface-active agents (surfactants) of both biological and synthetic origin which due to adsorption on the growing crystal edge can affect morphology of solid phase materials and their processes of mass exchange with the environment. These phenomena have not been sufficiently studied.

In this paper, the task was to determine the effects of surfactants on the morphology of struvite, including conditions of struvite interaction with ions Ni2+. As the object of the study model surfactants were selected: anionic sodium dodecyl sulfate (SDS), cationic hexadecyltrimethylammonium bromide (STAV) and nonionic polioksoetilen (20) sorbitan monolaurate (TWEEN 20). Struvite morphology was examined by optical microscopy, a microscope connected with a digital camera.

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It is shown that in the presence of these types of surfactants the size of the struvite particles formed reduces, which may imply their adsorption on the surface of the growing crystal edges. This result is manifested in the formation of struvite under conditions of supersaturated solution. However, the surfactant additives do not hinder struvite recrystallization process in solutions containing ions Ni2+. Crystals increase in size in recrystallization process, which confirms a possibility of metabolic processes of the solid and liquid phases, at least under conditions of low surfactant concentration (5·10–4 M). More detailed conclusions will require further study of appropriate systems.

УДК 544

I.Y. Zorichev, I.A. Permjakova, V.V. Volkhin.

INTENSIFICATION OF TRANSESTERIFICATION IN LOW-WASTE TECHNOLOGY OF SECOND GENERATION BIODIESEL

Perm National Research Polytechnic University

During the research of the conditions for obtaining biodiesel using alkaline catalyst KOH ethyloleate was used as a homogenizer of the oilethanol mixture. In doing so, dependence of the transesterification rate on the system transition into homogeneous state was investigated. The study established that the temperature of the system homogenization depends on concentration of ethyloleate in the reaction mixture.

In general when choosing temperature and concentration of ethyloleate, we had to solve the following tasks:

1) The reaction products of the transesterification of oil with ethanol at room temperature should be in a heterogeneous system, wherein the upper phase is a mixture of ethyl esters of fatty acids in the form of triglycerides in the starting oil.

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2)The components of the reaction mixture should be in a homogeneous state at the temperature of 70 °С.

3)The composition of the upper phase containing biodiesel must comply with European standard EN14214, or be close to it. The components that do not comply with the standard, should be easily removed.

During the experiments it was found that the upper phase has a high content of esters. This phase also contains a small amount of ethanol, which can easily be removed by evaporation. It has been established that at high concentration in a mixture of KOH, in contrast, a decrease in output of ether was observed. This is due to the fact that KOH is not a catalyst by itself, the latter being a product of the reaction of KOH and ethanol – potassium ethoxide. This reaction proceeds with water formation, which may lead to the hydrolysis products of the transesterification of ethyl alcohol and triacylglycerides.

The simultaneous occurrence of these processes can lead to further biodiesel contamination with impurities, in particular glycerol.

It is worth noting that in the production of biodiesel glycerol is produced in large quantities, and its processing is a serious problem. We plan to solve this problem by using soil microorganisms. For this purpose we will use a medium in which glycerol is used as a carbon source.

УДК 623.19.47

A.S. Makoveev, A.Y. Druk, L.S. Pan

OBTAINING BIOSORBENTS BY MODIFYING ALGAE BIOMASS FOR ADSORPTION OF IODINE FROM THE GAS-AIR PHASE

Perm National Research Polytechnic University

Relevant to modern society is the problem of environmental safety. During the production of medical products, nuclear waste disposal and accident elimination at nuclear facilities, the environment receives vari-

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