DEEP EUTECTIC SOLVENTS AS AN ADDITIVE IN MODIFICATION OF MEMBRANEFOR NANO- AND ULTRA- FILTRATION: PHYSIC-CHEMISTRY CHARACTERISTICS, FTIR STUDY AND ELECTROCHEMICAL BEHAVIOR

Deep eutectic solvents (DESs) are a new class of solvents that can offset some of the primary drawbacks of typical solvents and ionic liquids. They are synthesized by simply mixing the components that interact with each other through hydrogen bonds, and form a eutectic mixture with a melting point much lower than each component individually. Deep eutectic solvents is usually liquid at temperatures below 100 °C. Thanks to these great advantages, deep eutectic solvents is attracting more and more attention in many areas of research. Very recently, great attention has been paid to new pioneering attempts aiming at deep eutectic solvents into the field of chemical engineering, including membrane science and technology. Even if just a same works have been currently reported in applying deep eutectic solvents in membranes, the consideration on this new type of solvents is continuously growing. New deep eutectic solvents based on choline chloride (ChCl)–lactic acid (1:2 M ratio) was obtained and its electrochemical characteristics was studied. The synthesis of deep eutectic solvents was confirmed by FA nuclear magnetic resonance (NMR) spectrometry method. FTIR study provided further details into hydrogen bonding upon mixing. FTIR results confirmed that H-bonds, occurring between two components in deep eutectic solvents, were the main force leading to the eutectic formation. The frequency at 3221 cm−1 can be attributed to the oscillations of the O-H bond in the formation of OH-Cl-ChCl. The main physicochemical characteristics of deep eutectic solutions (density, pH) are determined. The electrochemical behavior was investigated of choline chloride (ChCl)–lactic acid deep eutectic solvent (DES) by cyclic voltammetry. The method of cyclic voltammetry found that the oxidation of deep eutectic solvents is fixed at a potential of Ea1 = 0.54 V.

THE STUDY OF THE SORPTION PROPERTIES OF FILTERING MATERIALS BASED ON TITANIUM PHOSPHATE - POROUS TITANIUM COMPOSITION

Inorganic sorbents are more selective in comparison with commercial ion exchange resins towards of metal ions. However, inorganic sorbents characterized not high kinetic properties. One of the way to increase the kinetic rate of inorganic sorbents is to reduce the particle size of these materials, other way is synthesizing inorganic sorbents as porous products from powder materials. A sample of such inorganic sorbents is titanium phosphate of various compositions. Studying the properties of microfilters based on composition titanium phosphate - porous titanium has been developed. The sorbents based on acidic titanium phosphate Ti(HPO4)2∙H2O were used for filtering solution with Fe(II) content. It is found that the number of impregnations with inorganic sorbent modificator is important and influence filtration process. The obtained results demonstrated that after the first impregnation of porous material with a smaller pore size, it is possible to obtain such sorbent as a mass content of powder material. By varying the ionic form of titanium phosphate, the porosity of titanium, the amount of impregnation, it could be possible effect on the sorption Fe(II). The sorption properties of titanium-titanium phosphate microfilters were studied by potentiometric titration in the NaCl-NaOH system, as well as the sorption of Fe2+ ions. The degree of purification for Fe(II) from solution with a concentration of 10 mg/l is 64 %. Application an electric potential to the microfilter of porous titanium - phosphate titanium increases the degree of purification of Fe(II) to 88 %.

REMOVAL OF BERYLLIUM (Be2+) FROM WATER SAMPLES BY SORPTION PROCESS: A REVIEW

Beryllium (Be2+) is an important industrial metal because of its unusual material properties: it is lighter than aluminium and six times stronger than steel. Beryllium is a strategic metal due to its low density combined with its strength, low neutron absorption, high melting point and high modulus of elasticity. Beryllium is often alloyed with other metals such as copper and is an important component of materials used in the aerospace, automotive, energy, defense, medical, and electronics industries. However, beryllium and its compounds are very toxic, especially to the lungs, skin, and eyes. Beryllium compounds are known carcinogens based on sufficient evidence of carcinogenicity in humans from human studies. Toxic effects of beryllium include immunotoxic, allergic, mutagenic, and carcinogenic effects. Mammalian tissues do not excrete it, so the effects are cumulative and can lead to death at high concentrations. Therefore, removal of Be2+ is important. In this review, the removal of Be2+ from water samples by sorption processes using different sorbents was summarized. The effects of process parameters on the removal of Be2+ have been summarized. The work discussed showed that ion exchange resins, various modified biosorbents metal oxides can be used for the removal of Be2+. The results showed that the pH of the solution has an important effect on the removal rate. Sorption kinetics vary from 3 minutes to 48h. When the functional groups are on the surface of the sorbent, the sorption process is rapid. However, if the surface of the sorbent is covered with oxides such as magnetite, it takes longer to reach equilibrium. Published work shows that more than 99 % of Be2+ can be removed from solution.

CONCENTRATION OF SOLUBLE SALTS IN COOLING WATER OF POWER PLANTS WITH BLOW DOWN RECIRCULATION

The method for calculating the dynamics of concentration of soluble salts (tracers) using the assumption of their homogeneous distribution in the water volume of the circulated cooling system (CCS) under the conditions of recirculation of part of the purge water was proposed. The assumption of homogeneity of salt distribution is substantiated by the fact that the period of mixing of cold water (CW) in CCS is equal to several hours, and the period of setting the concentration limits is calculated in tens of days. In this approximation the law of change of concentration of tracers in time from the moment of their supply in CCS in modes without and with recirculation of a part of purge water and without any processing is received. It is shown that without recirculating treatment, recirculation of purge water increases the maximum salt concentration and the time to reach it. Attention is drawn to the fact that the flow rate consists of two parts: controlled and uncontrolled. When calculating the allowable amount of purge recirculation, it is necessary to use the value of the total purge flow. It is important to understand that the relative change in total purge is always less than the controlled one. To obtain the cost of full purge, it is necessary to calculate its uncontrolled part. The procedure for calculating the uncontrolled purge is given in the paper. Since there are restrictions for of maximum allowable concentration (MAC) on the concentrations of tracers in the CCS, the expressions obtained in this work are consistent with the requirements of the MAC and allow for a given degree of concentration of salts φ, to calculate the limit of recirculation flow. It is shown that the recirculation regime can be applied without additional measures for CCS with a low initial degree of salt concentration and low concentration in the feed water. The proposed algorithm is used to predict the results of recirculation in the case of a specific CСS for thermal power plants with an electrical capacity of 1200 MW and the ratio CMAC/C0 = 5. It is shown that in this case recirculation has significant economic and environmental effects. However, at high, concentrations of tracers C0, compared to MAC, feed water recirculation is meaningless. The calculation algorithm applies to tracers, i.e. salts that do not give deposits, but only limited by the MAC requirements and the risk of corrosion or environmental considerations. Therefore, the above technique cannot be directly used for sparingly soluble salts, such as calcium carbonate. In this case, it requires significant correction. Note the convenient use in calculations of the earlier introduced by us concept of regime (dynamic) factor φ, especially when comparing the real consumption of the main flows of ССS to calculated and in determining the evaporative capacity of cooling towers, or assessing the degree of salt concentration.

PROBLEM OF ANTIBIOTICS IN NATURAL WATER: A REVIEW

The paper is devoted for influence of antibiotics contamination of natural water on environment, aquatic biosystems and public health and possible solutions of this problem. Untreated or ineffectively treated wastewater is a source of different pathogenic microorganisms and toxic chemicals, including organic and inorganic compounds. A lot of organic contaminants are genotoxic, provoke endocrine disruption and have immune toxicity. In modern world people use a lot of diverse antibiotics for the treatment of various bacterial infections, but antibiotic overuse and insufficient removal by wastewater treatment plants are resulted in accumulation and biotransformation of these compounds in aquatic environment. Antibiotics are pollutants which are very harmful for environment. They cause reduction in microbial biodiversity, including bacterial communities with important ecological functions. It provokes changes in water and soil properties, including pH, nutrients content, soil moisture and many others. Low concentrations of antibiotics cause an occurrence of pathogenic microorganisms which are resistant to antibiotics. It has very negative influence on public health due to increasing of health risk and complication of a medication. Antibiotic type, water and sediment compositions, pH, organic matter, specific surface area and temperature and insolation level have very big influence on distribution and behavior of antibiotics in natural water-sediment systems. Many antibiotics are biodegradable; they are transformed in human organism or by aquatic ecosystem (various plants, algae, bacteria, fungi, etc.). But some antibiotics, including ciprofloxacin, are very stable. These persistent organics are dramatically more harmful for ecosystem stability. In case of ciprofloxacin antibiotics in surface water direct photolysis causes formation of organic compounds, which are more toxic and less photolabile than initial antibiotics. So, the toxicity of pollutants increases synergistically and it cannot be ignored. Nowadays antibiotics removal is very important in drinking water and wastewater treatment due to significant environment and health effects of these pollutants. There are a lot of approaches in antibiotic removal from water, including adsorption, nanofiltration, advanced oxidation processes, etc. All these methods have some advantages and disadvantages. Catalytic photodegradation is one of the most popular methods of antibiotic removal. This process is simple, highly effective and makes possible transformation of antibiotics into components with lower toxicity and environmental impact. Also photocatalysis do not produce a lot of wastes unlike coagulation (sludge) or nanofiltration (concentrate).

PREPARATION OF POLYACRYLONITRILE MEMBRANES WITH ANTIBACTERIAL PROPERTIES

We describe the method of formation of polyacrylonitrile membranes with antibacterial properties by addition into the casting solution casting of antibacterial polymeric compounds: polyhexamethyleneguanidine chloride, oligourethanesemicarbazide with terminal cationic pyridinium chloride groups, and the polyvinylpyrrolidone-iodine complex. We investigated the effect of the addition of antibacterial compounds to the casting solution casting on the physicochemical, transport and antibacterial properties of the obtained membranes. We show that increasing the concentration of the bactericidal additives in the casting solution to 3% (wt.) leads to a change in the investigated physicochemical characteristics, water flux and membrane rejection, of polyethyleneglycol and low molecular weight electrolyte type 2-1 (CaCl2). We found that membranes prepared from the casting solution with 3% (wt.) of antimicrobial substances are characterized by high antibacterial activity.

IMPROVEMENT OF GAS MONITORING METHODS IN WATER OF THE HYDROGEN-WATER COOLING SYSTEM OF NPP’S TURBINE GENERATOR

The relevance of research is to ensure and improve the reliability of turbine generators (TG) with a hydrogen-water cooling system by monitoring the content of dissolved gases in the water of a hydrogen-water cooling system with monoethanolamine (MEA) – C2H7NO and water vapor in the cooling hydrogen of the turbine. In this work, the influence of ultrasonic vibrations on the decomposition of a mixture of water and turbine oil, organic acids (acetic acid - С2Н4О2, formic acid - СН2О2, oxalic acid - С2Н2О4) or monoethanolamine was determined. The distribution coefficients values were definedd for the following dissolved gases Н2, О2, N2, СО, СН4, С2Н2, С2Н4, С2Н6, С3Н6, С3Н8, which are of degradation products of water mix components when exposed to ultrasonic oscillation in the following system: «dissolved gas – mixture «water + monoethanolamine» – extractant argon (Ar)». The obtained values of the Кі distribution coefficients for dissolved gases in systems «dissolved gas – mixture «water + С2Н7NО» – extractant argon (Ar)» at a temperature of 293 K and a concentration of С2Н7NО at the level of 1 g/dm3 are close to similar values for dissolved gases in deionized water. The principle flow chart of multichannel gas chromatograph for detecting dissolved gases in water and steam of water in hydrogen was developed. Developed flow chart of 4-chennel gas chromatographer for defining dissolved gases in water includes the one gas chromatographer with conductivity detector, methanator, flame ionization detector, argon gas-bearing and supplementary gases of hydrogen and air.

ELIMINATION OF ANTIBIOTICS BY PHOTOCATALYTIC METHODS

Antibiotics have been found in water bodies of different origin around the world, including natural waters. The presence of antibiotics in natural waters is already an important environmental problem, as they pose a potential threat to the environment. Analysis of the literature shows that photocatalytic methods are considered to be more promising than biological methods and adsorption processes for the treatment of water bodies contaminated with antibiotics and other pharmaceuticals. The aim of this study was to determine the efficiency of antibiotics removal (ciprofloxacin, sulfamethoxazole and trimethoprim) by photocatalytic methods over TiO2 photocatalyst modified with yttrium oxide. For this purpose, a commercial sample of TiO2 P25 (Evonik) was modified, which was further characterized by X-ray diffraction and X-ray fluorescence analysis methods. The obtained data indicate the presence of yttrium in commercial P25 sample after modification. Studies on the removal of antibiotics from aqueous solutions by photocatalytic methods were carried out in three ways: employing modified photocatalyst; combination of photocatalyst and hydrogen peroxide, and the combination of photocatalyst with hydrogen peroxide and ozone. The results of research demonstrate high efficiency of photocatalytic methods in the oxidation of antibiotics in aqueous solutions, among which the greatest oxidation is achieved using the combination of heterogeneous photocatalyst, hydrogen peroxide and ozone.

BIOLOGICAL WASTEWATER TREATMENT IN CONTEXT OF CIRCULAR ECONOMY

With the beginning of Anthropocene epoch, nature is facing a lot of environmental problems that drastically increased in the last century. On the current rate of resource consumption, soon nature will lose the ability for self-restoration. In order to avoid inevitable consequences of resources exploitation, new approaches should be developed in all areas of human life. Linear economy concepts that were utilized for a long time and were based on use and disposal of each separate resource depending on the purpose is not sufficient anymore. More holistic approach should be applied to overcome the challenges that we are facing now. Application of circular economy concepts for wastewater treatment facilities has a great potential to enhance sustainability of water management. This paper will focus on circular economy concepts applied for modern pilot installation that combines biological treatment and membrane separation and discusses the potential for the full-scale implementation. Since, pilot plant was operated without any chemicals addition it eases the use of the waste sludge that is received as a by-product for different purposes as agricultural application and biogas production.

ADSORPTION OF 4-CHLORPHENOL BY BROWN COAL ACTIVATED BY POTASSIUM HYDROXIDE

The purpose of work is to evaluate the 4-chlorophenol (CP) adsorption capacity of brown coal activated carbons (ACs) prepared at different temperature of KOH activation. ACs were obtained in three stages: 1) impregnation of coal with a KOH solution, 2) heating (4 deg/min) in argon to a given temperature t (400-800°C) and exposure for 1 h, 3) cooling, washing from KOH, drying. The samples are designated as AC(t). Based on the N2 adsorption-desorption isotherms, the ACs total pore volume (Vt, cm3/g) and specific surface area (S, m2/g) were determined. The ACs adsorption capacity were measured at 25°С, CP concentration ≤700 mg/L, АC dosage – 1 g/L. The alkaline activation temperature was found to be a key factor in forming porosity of ACs and ability to adsorb CP. The CP maximum capacity (ACP(m), mg/g) increases 6.6 times up to 307 mg/g for AC(800) having S=1142 m2/g. The specific adsorption capacity (ACP(S) = ACP(m)/S, mg/m2) sharply decreases in a sample range from AC(400) to AC(550) and weakly depends on temperature at 550-800°C. The kinetics of CP adsorption is best described by a pseudo-second order model. The rate determining stage is the interaction of CP molecules with AC surface. The CP adsorption isotherms are best described by the Langmuir model. The dependence of the ACP(m) from S can be approximated by three linear equations that probably correspond to the three regions of forming surface adsorbtion centers (AdCs). The first (S≤370 m2/g) is characterized by a small adsorption capacity increment (kS=0.103 mg/m2), but a significant (16.4 times) decrease in the specific capacity ACP(S). In the second region (S=370-770 m2/g, t=550-750°C), capacity increment is 10 times more (kS=0.985 mg/m2) and in the third region (S≥770 m2/g, t≥750°C) the increase in CP capacity is the smallest (kS=0.067 mg/m2). The thermoinitiated formation of AdCs is assumed to be not proportional to the increase in surface area, and their chemical structure and reactivity is determined by the alkaline activation temperature.