Role of Interfaces in Environmental Protection

Water is continually moving around, through, and above the earth as water vapor, liquid water, and ice. In fact, water is continually changing its form. The Earth is essentially a “closed system”, like a terrarium. That means that the Earth neither, as a whole, gains nor loses much matter, including water. This means that the same water that existed on Earth millions of year ago is still here. Thanks to the water cycle, the same water is continually being recycled all around the globe. It is entirely possible that the water you drank for lunch was once used by some other person for bathing.

All processes for particle removal in potable water treatment require proper design and control of solution and interfacial chemistry and of interparticle collisions. This is also true for most processes used to remove particle-reactive pollutants such as natural organic matter (NOM) and arsenic. The treatment processes involved span a range from conventional plants with coagulation, flocculation, sedimentation and packed bed filtration through direct filtration, flotation, solids contact systems and microsand facilities and on to various membrane technologies. The “collisions” provided by each of these technologies differ in important ways. It follows that the “chemistry” most appropriate to each of them can also differ significantly and substantially. Similarly, the aggregation and settling of particles in rivers, lakes, estuaries and the ocean and also the deposition of colloidal particles in ground waters depend on surface and solution chemistry and on collisions of suspended particles with each other or with other media such as aquifer materials. This paper presents a discussion of the similarities and the differences in the chemistry and the collisions appropriate to some of these aquatic systems. It includes a focus on the colloid chemical role of natural organic matter in potable water treatment and in natural waters.

In the field of environmental separation and remediation, many submicron inorganic particles offer favorable properties in regard to selective separation and/or chemical transformation of target contaminants. For example, i) hydrated Fe(III) oxides or HFO particles can selectively sorb dissolved heavy metals like zinc, copper or metalloids like arsenic oxyacids or oxyanions; ii) Mn(IV) oxides are fairly strong solid phase oxidizing agents; iii) Magnetite (Fe₃O₄) crystals are capable of imparting magnetic activity; iv) elemental Zn° or Fe° are excellent reducing agents for both inorganic and organic contaminants (1-6). Extremely high surface area to volume ratio of these tiny particles offers very favorable kinetics for selective sorption and oxidation-reduction reactions. Nevertheless, these particles cannot be used in fixed-bed columns, in underground reactive barriers or in any plug flow type configuration due to excessive pressure drops and poor durability. On the contrary, many commercially available porous polymeric beads are very durable and offer excellent hydraulic properties in regard to pressure drops. The prices of these polymeric particles are quite competitive and the trend around the globe indicates that they will further decrease in the future. Ideally, it would be very desirable to develop a new class of polymeric/inorganic materials that combine the excellent hydraulic characteristics of spherical polymer beads with favorable sorption/redox/magnetic properties of inorganic nanoparticles. There remain many possibilities and new opportunities to effectively apply these hybrid particles for environmental separation and control.

The lyophilic structure-mechanical barrier formed by the interfacial adsorption layer is considered as a factor of strong stabilization of disperse systems with respect to high concentrations of disperse phase and electrolyte. Such barrier must possess two principal features: intrinsic mechanical strength of the layer — preventing coalescence, and high affinity of the external side of the layer and dispersion medium — opposing coagulation; independent experimental approaches for their quantitative characterization are presented.

Mixing of dry powders with oil or liquid binder is often done to minimize segregation and dust pollution during handling and transport. The amount of binder required is determined empirically due to inadequate models. Oil as a binder forms capillary bridges between particles. In the present study, theoretical expressions are developed for the calculation of the capillary force at different oil interlayer thickness between particles. Experimental measurements using AFM were conducted to validate the theory for particle/particle and particle/wall interactions.To initiate flow in a cohesive powder, the work of shear stress is primarily utilized to break the oil bridges. The mechanical work done due to shear is compared with the energy of breakage of the oil bridges. Using the capillary energy approach, a theoretical expression is developed for the calculation of the unconfined yield strength of the powder. This expression was validated experimentally by measuring the unconfined yield strength of silica powder in a Schulze’ cell with different oil concentrations.

In concentrates of natural and drinking waters of Dnieper river basin in Kiev region with enrichment factor of 1,80-105–3,47.105 PCB (PCB524, PCB664, PCB1015, PCB1185, PCB1055, PCB1536, PCB1386, PCB1807, PCB2008) have been identified and their isomeric-specific composition (tetrachloro-— heptachloroisomers) has been determined at MDL for total concentration of PCB at level as low as 0,19–0,38 ng/L and 0,19–0,36 ng/L calculated by the mean value in groups of pentachloro—and hexachloroisomers respectively.

Current considerable application of atomic energy along with the Chornobyl Shelter problems makes the ecology of the nuclear energy of great importance in Ukraine. Therefore the elaboration of advanced dosimetric materials for radiation monitoring in the wide energy of ionizing radiation (IR) and dose ranges is highly requested.During last years we have been studying luminescent dosimetric materials — europium (Eu) incorporated into solid oxide, phosphate, fluorohalide lattices [1]. Recently we have extended our studies including Cu- and Eu- doped tetraborates. Interest in these materials is connected with their tissue equivalency and very promising properties in the personal and environmental dosimetry.Dosimetric characteristics are obtained on the basis of time-resolved radioluminescence (RL) and three-dimensional thermoluminescence (3DTL). This presentation includes the following: Radioluminescence and dosimetric properties in the high dose-rate region (105–106 Gy/s)Thermoluminescence and dosimetric properties in the low dose region (10−3–10−1 Gy)The main RL characteristics of tested materials: high conversion efficiencyradiation and thermal stabilitylinear dependence of RL and TL properties in the wide dose range: 10−3–106 Gy allow considering them as promising materials for extreme and environmental dosimetry.

The largest environmental pollution in the past few years was the cyanide pollution coming from mines of non-ferrous metals in Romania polluting the rivers Tisza and Szamos in the beginning of 2000. In addition to the direct damage at the time of pollution, there arises the question whether cyanide adsorbs in the settling of the river or in the surrounding soil. If it adsorbs, then it can reappear in the river water or in the soil solution, then from there getting to the source of drinking water it can have long-lasting effects. Therefore our aim was to determine whether the cyanide ion can adsorb in the settling of river Tisza, or in the soil near the shore as free cyanide ion or in the presence of Zn- and Cu ion coming together with cyanide pollution.

The speciation of Uranium fission product (particulate, dissolved organie and dissolved inorganic matter) in the waters of the Dnieper and PrypyatRivers was studied after the Chernobyl accident. The initial contamination of surface waters consisted predominantly of “bot” particle borne 90Sr, 95Nb, 95Zr, l03Ru, l06RU, 134CS, 137CS, 140La, 141Ce, and 144Ce. Over 15 years tbe total radioactivity in water decreased due to sedimentation and radioactive decay. At the same time the fraction of dissolved 90Sr and 137CS increased. This fraction bas now reaches 99% and about 80% of 137CS and >95& of 90Sr in river water occurs as cationic species. Tbe remainder is distributed equally between suspended and dissolved organic matter. The transfonnation of suspended particle borne radionuclides into dissolved species is described by the equation: k _t = exp(-kt), where k is the transformation rate constant. Values of k were 0.126 y−1 for 137CS and 0.241 y−1 for 90Sr. The specific activity of the suspended particulate matter in river waters reacbed 15 kBq kg−1 for 137CS and 700 kBq kg−1 for 90Sr. The cationic species represent tbe main part of the fission products that are transported into the Black Sea. 6·1011 Bq for 137CS and 7·1012 Bq for 90Sr are transported as dissolvedspecies from the ExclusionZone into the Black Sea. From the geochemicalpoint of view we presentlyface the most dangerous period of radionuclide mobilizationby the fonnation of dissolved ionic species.

The accident at the Chernobyl Nuclear Power Plant (ChNPP) 4th Unit on 26 April 1986 was accompanied by the destruction of a reactor core and the release of solid and gaseous radioactive products. As a result of the accident, a part solid radioactive materials of the 4th Unit was dispersed by the explosion. The hot particles released settled on the surface of soil hundreds kilometers from ChNPP in the Sweden [1], Germany [2,7], Poland [2,3,7], Belorussia [4] and in particular, Ukraine [5,6,8]. The size of hot particles vary from one to hundreds microns. The bulk radioactivity of a single particle based on the initial activity calculated for 26th April 1986 might differ by hundreds of kBq. While particle size tends to decrease with increasing distance from the 4th Unit, some relatively large particles of 100–300 micron in size were collected 12 km West of ChNPP. Phase, chemical and radionuclide compositions of hot particles are essentially heterogeneous [1–8]. We have suggested dividing all hot particles into two main groups: 1) fuel particles — with relatively homogeneous matrix consisted of uranium oxides, UO_2+x; 2) fuel-constructional particles — with a complex chemical matrix and/or multi-phase composition that is a result of high-temperature interaction between nuclear fuel, (UO_2+x), and cladding materials such as zircaloy and stainless steel composed of Fe-Gr-Ni. The temperature could have exceed 2600°C. In some places of Western Plume in Chernobyl region these particles achieve up to 40 % of all hot particles [8]. Radionuclide composition of hot particles depends on the chemical and phase composition of their matrices [1,2,7,8].

Linear relationships including molecular deformation polarizability and acid-base hydrogen bonding parameters of Abraham’s scale are proposed to connect the adsorption thermodynamic functions (adsorption enthalpy, entropy, free energy, or related to later value, the logarithms of gas-particle partition coefficient or gas Chromatographic specific retention volume) with contributions of nonspecific and specific interactions between volatile organic compounds (VOCs) and adsorption sites of different natural solid and liquid surfaces. The model sufficiently describes adsorption thermodynamics of VOCs on surface of various carbonaceous materials, minerals, inorganic oxides, water, air/water interface, wet soils and plants. The coefficients of the model show high dependence of adsorption characteristics on the surface chemistry. Relations between the models’ coefficients and the surface characteristics determined by inverse gas chromatography (dispersive component of surface free energy, donor and acceptor numbers of solid surface) are derived. This approach was employed to predict high enrichment factors for different VOCs identified in samples of young ice from Western coastal Antarctica.

Volatile compounds in ice blocks sampled from warm glacier in Western coastal Antarctica were analyzed. The dating of the young ice and air in aged ice probes was performed using quantitative analysis of radioactive isotopes 210Pb and 14C in CO₂. The age of the samples varied from 20 to 4,700 years. The greenhouse (CO₂ and N₂O), sulfurcontaining gases (COS, CS₂), 1-propene and halocarbons of natural origin (CF₄, CH₃Cl, C₂H₅C1, CH₂=CHCl, CH₃Br, CH₂Br₂, CHBr₃, CH₃I, CH₂=CHI and C₂H₅I) were identified in these samples. All these compounds, except CF₄, demonstrate high mixing ratios in comparison with their content in present air. A tendency for the enhancement of the enrichment factors with increasing Henry’s law coefficient of the gases was observed for all samples. Possible reason of the enrichment in the warm glacier may be dissolution of the gases in meltwater percolating through the underlying firn layers, subsequent refreezing of the enriched solution during cold season and repeating of the melt-freeze cycles. This study suggests that increased amounts of naturally produced halocarbons, sulfur-containing gases and their resultant halogen and sulfur species may be released to the atmosphere by possible future global warming or by El Nino. This increase may result in a greater contribution by natural halocarbons and sulfur-containing gases to Antarctic tropospheric ozone chemistry and stratospheric ozone depletion.

It has been estimated that 10 m people die each year from drinking contaminated water [1]. Contaminants include heavy metal ions, such a Pb(11) and Cd(11) (principally from sewage waste), fertilisers, pesticides and surfactants (from detergents and other household and personal cleaning products). Many options for their removal are available, including the use of such materials as activated carbon and ion-exchange resins [2]. Colloidal microgel particles offer a novel, alternative method for water purification. Microgel particles are essentially cross-linked, polymer latex particles, which swell in a good solvent environment for the polymer concerned [3]. The degree of swelling is controlled by the extent of cross-linking. These types of particles may be prepared by conventional latex polymerisation routes, such as dispersion or inverse-microemulsion polymerisation. The cross-linking is achieved by the use of low levels of a bifunctional co-monomer. The main feature which makes microgel particles suitable for the absorption of species for aqueous media is the facility to build-in ”binding” groups into the interior of the particles, which associate with the species to be removed. This is often achieved by copolymerising, with the matrix monomer, an additional monomer having the required functionality. In this paper the potential use of microgel particles as water clean-up agents will be illustrated by three specific examples.

In practice of water treatment by membrane filtration, fouling of membranes is the dominant cause for the decline of permeate flux. Different techniques, such as water pretreatment, improved hydrodynamics, membrane treatment, are used to control fouling [1–4]. Membrane treatment (or pre-treatment) by appropriate surfactants, polymers or colloids is applied to increase homogeneity and/or hydrophilicity of the membrane, and this way to reduce fouling [3,4].

Syndiotactic polystyrene (sPS) is liable to produce polymer-solvent compounds with a large variety or organic solvents. The solvent molecules can be removed while keeping the original crystalline lattice unchanged, thus producing emptied chlathrates which are nanoporous and possess the propensity of absorbing again solvent molecules in water even to very low amounts. So far these materials were obtained as powders. Here it is shown how membranes possessing both subnanoporosity and microporosity can be prepared. Several approaches have been used: gel formation5 or exposure of the solid sPS to liquid or vapour solvent. These polymer membranes might be of interest for ultrafiltation processes used in water purification. The thermodynamic of preparation of such systems as well as their structure and morphology are discussed.

In order to better understand and predict the influence of main solution parameters (pH and ionic strength) on aggregation/adhesion of “hairy” colloids mimicking bacteria, a simple interaction model is proposed. In this model, the van der Waals interaction energy between two spheres is combined with the electrosteric interaction energy between brush layers of flexible polyelectrolyte chains end-grafted on the spheres. The latter interaction energy component is expressed using simple asymptotic scaling approximations (omitting their numerical prefactors) derived earlier (Pincus, P.: Colloid stabilization with grafted polyelectrolytes, Macromolecules, 1991, 24, 2912-2919) for the mean thickness L and interaction force P of planar polyelectrolyte brushes in the so-called strong charging limit (SCL) and the strong screening limit (SSL) on the assumption that the distribution of monomers throughout the brushes is uniform. Any other interaction components (double-layer, structural or acid-base, hydrophobic, bridging, etc.) are neglected. The nonelectrostatic (excluded volume) interactions are also omitted. Both quenched and annealed polyelectrolyte types (with the constant and pH-dependent charge, respectively) of brushes are considered. The number of monomers per chain N, grafting density σ and the monomer size a* are proposed as brush parameters. The fraction of elementary charged monomers f is the next parameter which however may depend on the solution conditions for annealed brushes. The above parameters can be estimated by identifying them with the known molecular parameters and/or from the fixed charge density — a parameter obtainable from the soft particle electrophoretic analysis (Ohshima, H.: Electrophoretic mobility of soft particles, J. Colloid Interface Sci., 1994, 163, 474-483). Three sets of the brush parameters are used to model the effect of ionic strength and/on the interaction energy between Gram-negative bacteria in the SSL regime where the quenched and annealed polyelectrolyte brushes are expected to behave identically. Generally, a step-like interaction energy-vs-separation profile is obtained with a pseudosecondary minimum (no maximum), being in line with the conception of secondary minimum aggregation and adhesion of bacteria. An opposite influence of increasing/ and ionic strentgh on the pseudosecondary minimum depth (decrease and increase, respectively) is found which is expected but not predictable by the DLVO-based or steric interaction models. Dramatic changes in the position and depth of that minimum also indicate a necessity of proper evaluation of the brush parameters but, at the same time, reveal a possibility of accounting the wide variability in the bacterial cell wall structures (also inferred from the soft-particle electrophoretic analysis).

An overview of current trends in the application and characterization of new environmental sorbents is presented. These sorbents can take a broad spectrum of chemical forms and different geometrical surface structures. This is reflected in the wide range of their applications. The main types of adsorbents of practical environmental importance contain carbon adsorbents (active carbons, activated carbon fibers, carbon molecular sieves, mesocarbon microbeads, carbonaceous nanomaterials), mineral adsorbents (silica gels, activated alumina, oxides of metals, hydroxides of metals, zeolites, clay minerals, pillared clays, porous clay heterostructures, inorganic nanomaterials) and such solids as synthetic polymers, metallorganic microporous and mesoporous materials, composite adsorbents and the so-called mixed adsorbents. Strong efforts are also directed on the development and broader application of the ion-exchange method that deals with the production of novel organic and inorganic ion exchangers of suitably chosen physicochemical properties. Main trends in the development of new selective materials referred to great ion-exchange capacity achievement as well as improvement of chemical, thermal and mechanical resistance is discussed in perspective of their impact on adsorption for environment (e.g., selective removal of relatively low levels of toxic or noble metal ions). Application of solid sorbents requires their many — faceted characterization and achievements in this field accelerate their synthesis and applications. The two groups of methods most commonly used are direct physical techniques and indirect methods such as sorption, chromatography, and thermal analysis. The former group of methods comprises electron and scanning microscopy, atomic force microscopy (AFM), X-ray diffraction, X-ray spectroscopy, small-angle X-ray spectroscopy (SAXS), solid-state NMR, Raman spectroscopy, etc. that provides direct information about physicochemical properties of solids sorbents. On the other hand, the second group of methods is very important because classical adsorption/desorption measurements are unavoidable to collect information on the adsorption behavior of a solid with regard to a given pollutant. This lectures presents the overview referring to a brief description and classification of modern environmental adsorbents, summarizes the adsorption / desorption methods aimed at their characterization and demonstrates various theoretical approaches to evaluate the adsorption energy and micropore-size distributions from the gas / solid and liquid / solid adsorption isotherms. Moreover, a special emphasis is placed on the molecular simulations of adsorption processes that include the understanding the synthesis of the novel adsorbents through simulation techniques and improved methods for their characterization.The main types of adsorbents of practical environmental importance contain carbon adsorbents (active carbons, activated nanomaterials), minerals adsorbents (silica gels, activated alumina, oxides of metals, hydroxides of metals, zeolites, clay minerals, pillared clays, porous clay heterostructures, inorganic nanomaterials) and such solids as synthetic polymers, metallorganic microporous and mesoporous materials, composite adsorbents and the so-called mixed adsorbents.Strong efforts are also directed on the development and broader application of the ion-exchange method that deals with the production of novel organic and inorganic ion exchangers of suitably chosen physicochemical properties. Main trends in the deveoplment of new selective materials referred to great ion-exchange capacity achievent as well as improvement of chemical, thermal and mechanical resistance is discussed in perspective of their impact on adsorption for environment (e.g., selective removal of relatively low levels of toxic or noble metal ions).Application of solid sorbents requires their many - faceted charaterization and achievements in this field accelerate their synthesis and applications. The two groups of methods most commonly used are direct physical techniques and indirect methods such as sorption, chromatography, and thermal analysis. The former group of methods comprises electron and scanning microscopy, atomic force microscopy (AFM), X-ray diffraction, X-ray spectroscopy, small-angle X-ray spectroscopy (SAXS), solid-state NMR, Raman spectroscopy, etc. that provides direct information about physicochemical properties of solids sorbents. On the other hand, the second group of methods is very important because classical adsorption/desorption measurements are unavoidable to collect information on the adsorption behavior of a solid with regards to a given pollutant.This lectures presents the overview referring to a brief description and classification of modern environmental adsorbents, summarizes the adsorption/desorption methods aimed at their characterization and demonstrates various theoretical approaches to evaluate the adsorption energy and micropore-size distributions from the gas/solid and liquid/solid adsorption isotherms. Moreover, a special emphasis is placed on the molecular simulations of adsorption processes that include the understanding the synthesis of the novel adsorbents through simulation techniques and improved methods for their characterization.

Optimisation of the biosorption process of waste water purification from surfactants and development of a biosorber construction on this basis require substantial preliminary research and technological studies.

This work presents different methods of adsorbents characterisation. Their use towards improved removal of malodorous compounds is considered. These methods are applied to different modified silica gels. At first, the synthesis conditions were optimised using aminopropylsilanes. Afterwards the stability of the samples against ethanol and water was examined. The modified silica gels are suggested to be selective adsorbents in the field of odour control.

In our previous papers methods of synthesis and properties of synthetic activated carbons of spherical granulation with SCN and SCS trade marks [1–3], as well as the advantages of the use of these adsorbents in haemoperfusion, i.e. adsorptive cleaning the blood of patients from toxic and harmful substances in the extracorporeal circle have been described [4, 5]. The technology of obtaining these activated carbons and haemosoibents on their basis are protected in Ukrainian and Russian patents [6, 7]. In this paper the interrelation between physico-chemical and medico-biological parameters of the specified adsorption materials is considered. Obviously, these parameters of the adsorbent directly determine its therapeutic efficiency and spheres of its application in the medical practice.

The removal of copper, zinc and nickel from aqueous solutions by biosorption using grapestalks and cork biomasses is reported. The adsorption isotherms were determined and the uptake capacity for copper with grape stalks and cork was, respectively, 19.9 mg/g and 16.5 mg/g, while for zinc was 18.3mg/g with grape stalks and 13.4 mg/g with cork and for nickel was 11.1 mg/g with cork. The kinetics of copper biosorption in both biomasses was studied and a second order model was fitted to the experimental data. Copper biosorption is a fast process and within the first 5 minutes 80% of the maximum capacity was attained. The calculated activation energy for the biosorption reaction of copper was 28±3 KJ/mol for grape stalks and 6±2 KJ/mol for cork biomass. These low values indicate that the metal diffusion inside the particles is the rate controlling step of the reaction.

The equilibrium of heavy metals adsorption on activated carbons is still in its infancy due to the complexity of operating mechanisms of metal ions binding to carbon with ion exchange, complexation, and surface adsorption as the prevalent ones [1]. Furthermore, these processes are heavily affected by the pH of the aqueous solution [1– 4]. The influence of pH was generally attributed to the variation, with pH, in the relative distribution of the metal and carbon surface species, in their charge and proton balance, as well [4, 5]. Therefore, the equilibrium constants of each type of the species on each type of the activated sites seem to be very important for the controlling of metals ions capture by activated carbons [2, 4, 6]. Unfortunately, there is currently no way to determine these quantities from experimental data directly, and it has been proposed [2, 4, 6 ] to develop and/or perfect state-of-the art theoretical predictive tools for the modelling of the adsorption process, when the equilibrium constants are treated as adjustable parameters. In general, such approach appears to be promising, although only few studies have been published in this area until now.

Activated carbons are the most commonly employed adsorbents. Their versatility stems from the geometrical and chemical heterogeneity of their surface. The notion of geometrical heterogeneity encompasses pores of different sizes and shapes as well as cracks, pits, and steps. Nowadays, activated carbons of a wide range of desired surface areas and pore structures are available commercially. It was only in the ′80s that the previously neglected but important subject of carbon surface chemistry was first analyzed in depth, since neither the surface area nor the pore structure was sufficient to explain many of the properties of carbon-supported catalysts.

In aqueous systems the interactions between clay mineral and metal oxide particles are generally governed by a local electrostatic field developing around particles. An electrified interface develops due to the formation of a multitude charged surface sites and the accumulation of countercharges in order to preserve electroneutrality. The composition of aqueous solution influences both the surface charging and the charge neutralization. The surface acquires an electrical potential different from the solution in which it is immersed. The distribution of charges in the electrical double layer and the potential decay from surface to bulk solution depends on the quality and quantity of dissolved species. Ionic species in the solid-liquid interfacial layer are situated closer to or further from the surface, depending on their size, charge, and ability to form chemical bonds with the surface sites. These may be specifically adsorbed species, which can bind to the surface through covalent interactions in addition to the pure Coulombic contributions [1], The presence of these ionic species has a direct influence on the surface charge. The formation of inner sphere complexes occurs, when ions bind directly to the surface while outer-sphere complexes form through water bridges [2,3,4]. Several dissolved organic compounds occurring in most aquatic environments have ability to form various complexes on the surface active sites. A chemically heterogeneous mixture of dominantly acidic products from microbial degradation and many other processes (e.g. oxidative polymerization of phenolic compounds in plants and soils, photolytic degradation) is called as natural or dissolved organic matter (abbreviated NOM or DOM) [5]. These small and macromolecular organic compounds (e.g. non-v olatile phenolic compounds, humic and fulvic acids) are rich in anionic functional groups, can be truly dissolved, associated with immobile phases or associated with mobile particles (e.g. colloidal clays and oxides), and so have an inherent influence on the surface charge state of inorganic mineral particles. The particle aggregation in aqueous dispersions of clay minerals and metal oxides is mainly determined by the pH and ionic strength of solution as well as the presence of multivalent inorganic ions and polyionic organic compounds, like humic substances.

TiO₂ nanosol particles were prepared by acidic hydrolysis of titanium tetraisopropoxide, and the incorporation of the anatase nanoparticles was next carried out between the layer silicate sheets by heterocoagulation method. TiO₂/montmorillonite nanocomposites with high specific surface areas (as_BET = 130-284 m2 g-1) were characterized and tested as photocatalysts by mineralization of phenol. Self-assembled multilayer films from Zn(OH)₂/ZnO nanoparticles and hectorite were prepared and the optical and structural properties were investigated. Significant photodegradation of β-naphtol and kerosene was found in the presence of the nanofilms, in the flow photocatalytic experiments. The degradation of 2-chlorophenol was investigated by a combination of TiO₂based photocatalysis and adsorption. The differently prepared adsorbent-photocatalyst systems were characterized by X-ray diffraction measurements. The most advantageous situation was found when the hexadecylpyridinium chloride-treated montmorillonite was used as adsorbent and Degussa P25 TiO₂ as photocatalyst, for which the highest rate of oxidation of 2-chlorophenol was observed. In this case the photocatalytically recovered adsorbent may be re-used without further regeneration.

A variety of individual and mixed fumed oxides based on silica, alumina, and titania was studied in the gas phase and aqueous suspension by means of XRD, NMR, IR, UV, optical and photon correlation spectroscopies, electrophoresis, potentiometric titration, adsorption of metal cations, nitrogen, water, low-molecular drugs, and polymers (polyvinylpyrrolidone (PVP), proteins (bovine serum albumin (BSA), gelatine)) and microorganisms (Proteus mirabilis).

The problem of obtaining high quality drinking water is a world-wide acute task. This is due to increased contamination of surface waters, which serve as main source of drinking water supply, by antropogenic pollutants. The most dangerous pollutants of surface waters are biological substances that cause serious infection diseases of the population. According to the WHO report, a substantial part of epidemics in different parts of the world is caused by consumption of poor quality drinking water. The use of strong oxidation agents as disinfectants is not always efficient because some of the biological contaminants like viruses, spore, cysts of protozoa are resistant to these agents [1,2]. That is why the use of water treated by these sorts of agents appears quite dangerous due to the presence of high quantities of chloration or ozonation products and to the insufficient purification from biologically dangerous compounds.

Subsurface contamination with petroleum products (oil) is one of the most important environmental problems. The paper presents two directions in studying the subsurface contamination with oil: 1 — research to assess contaminated sites including searching, observations, exploration, and remediation; 2 — investigations to design objects — potential contamination sources, principal goals of which are to estimate protective properties of the unsaturated zone and to determine the term of starting protective actions.

Inorganic cation-exchangers with phosphate functional groups have been synthesized for further using in ion-exchange-assisted electrodialisys. The ion-exchange and electric conductive properties of ion-exchangers containing Na+, K+, Cs+, Cu2+cations were studied. Migration of cations adsorbed by the ion-exchangers into the cathod compartment of the electrodialisys cell of has been investigated. A linear dependence of the cation transport on the time has been found. The Nernst-Planck and the Nernst-Einstein equations were used to estimate the apparent diffusion coefficients for cations in the bed of the ion-exchanger. It was shown that the mobility of sorbed cation depends on the radius and chemical composition of the ion-exchanger.

Flotation, traditionally applied in mineralogy, has been used more recently in wastewater treatment, soil and sediment remediation and paper de-inking. The latter types of application may differ from mineral separation by the fact that the particles that should be floated are often partially hydrophobic and this will have consequences for the use of collectors and frothers. It is shown that the effect of collector and/or frother addition on the Gibbs energy of particle-bubble (PB) attachment differs for high-energy and low-energy surfaces. With low-energy surfaces collector and frother addition will, in general, impair PB attachment and improve PB detachment. To illustrate the effects in practice, results on the remediation of three sandy sludges contaminated with soot and/or coal-tar particles with a high concentration of poly aromatic hydrocarbons are presented. The focus is on sludge flotation because large quantities of contaminated harbor sludge or polluted soil require treatment and remediation by flotation is a potential alternative for classification. The results show that in two of the three cases studied collector addition has a negative effect.

In the modern society a great amount of food, water, fuel etc. flows into human dwellings from outer environmental and in the form of waste is discarded to the outer environmental again. Among these substances water is consumed in largest amount in cities. The modern period based upon the rapid volume transportation with a large scale simple production way is about to be ended by environmental restrictions. It can be concluded, that all water systems are now in crisis.

At Azgir test site (earlier named “galit”) situated at the salt-dome height Bolshoi Azgir there were carried out 17 out of more than total 40 underground nuclear tests performed in Kazakhstan. This dome occupies the western part of the salt-carrying province to the north of the Caspian Sea between the Volga-river and the Emba-river [1].

The problem of soil contamination by heavy metals and radionuclides (HMR) is important at the present time for many countries. One of the most promising new fields of the remediation of soils contaminated by heavy metals is the development of the processes of bacterial transformation of metals from bound form into mobile forms that are accessible to extraction [1-4]. Natural remediation of soils contaminated by heavy metals (HMs) proceeds very slowly. For example, the half-removal of lead, copper, and cadmium is equal to 740-5900, 310-1500 and 13-110 years, respectively [5]. Therefore, the problem of the intensification of HMRs removal from the soils is urgent.

The problems of recycling iron, nickel and cobalt bearing fine particle wastes are discussed. This work was primarily done with Alnico type alloys. Laboratory and industrial melts were carried out in specialty metallurgy furnaces for the purpose of the recovery of the metal content in the wastes. Using the traditional electric arc furnace and the electro-slag crucible type-melting furnace smelting operations for this waste was tested. The use of the electroslag type furnace for metal recovery is unusual in Western countries. It was found that using this non-traditional type of furnace significantly increases the yield of metal. The possibility of combining the waste smelting operation by electro-slag technology with oxidizing refinement was confirmed.