Vol 41, No 6 (2019)

Principles of the world origin and structure in relation to the Mendeleev’s periodic law are presented in this paper. Our Universe consisting of hydrogen (88.6%), helium (11.3%), and other chemical elements (0.1%) has created very favorable conditions for life on the Earth, including the much-needed water—a unique substance with all its anomalies. Special attention is given to hydrogen, the first element of the periodic table, from which the formation of our solar system began. Moreover, hydrogen is a basic building material for all the other elements. It is shown that a fundamentally important fact implies that all the worlds consist of the same chemical elements of the periodic table; today the total number of the known elements in this table amounts to 118, including the artificially produced ones. There are no new elements in the Universe. And herein lies the genius of Mendeleev as the author of the periodic law and the whole grandeur of the law of understanding the world, in which the humanity lives, making it possible to predict the existence of new planets and the existence of unknown chemical elements in the periodic table that were not discovered earlier. The second unique substance on planet Earth is water, because it can simultaneously exist in three phase states: liquid, solid and gaseous with a multitude of various physical, biological and other anomalies violating the generally accepted laws of nature, but owing to which life exists on our planet. Indeed, it is just the entropy changes of the process that make a decisive contribution to all energy characteristics of transformation of some substances into others. The essence of all chemical processes occurring on earth in accordance with the laws of non-equilibrium thermodynamics consists in an infinite sequence of self-organization processes. Due to these laws, new types of structures can spontaneously arise that are characterized by a transition from chaos and disorder to the order and strict organization. Despite an enormous progress in the study of the Universe, its structure remains to be no less mysterious. It remains to find scientific evidence that there is a Supreme Being that generates the intellect inherent only to Human Being.

Organic pollutants in water have been the main contaminations of concern for man. 2,4,6-Trichlorophenol (TCP), is a toxic carcinogen phenolic derivative which exists in effluents of chemical industries and the removal of this pollutant is critical. As the removal of TCP from industrial effluents is important, various techniques have been applied such as adsorption, chemical oxidation, chemical coagulation, and anaerobic biodegradation. In adsorption technique, nanobentonite is considered as a suitable adsorbent due to the low cost, small size of particles, large surface area, naturally available, and intense adsorption capacity. To separate adsorbent particles easily through an external magnetic field, magnetic nanomaterials, such as Fe₃O₄, can be fixed on nanobentonite. In this research, magnetized bentonite nanocomposite was synthesized for fast adsorption of TCP from aqueous solutions. The adsorbent was characterized by a Vibrating-Sample magnetometer (VSM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared spectroscopy (FTIR), X-Ray diffraction (XRD) and Zetasizer Nanoparticle analyzer and the effect of adsorbent dose; pH and contact time parameters on the adsorption process of TCP were evaluated. Moreover, the isotherms and adsorption kinetics were studied. The pH 5 was considered as the optimal pH. The results of kinetic experiments showed that by increasing the contact time, the adsorption efficiency was increased and the equilibrium contact time was found to be about 60 minutes. In optimal pH and equilibrium time (60 min) conditions with the adsorbent dose of 1 g/L, the percentage of adsorption by magnetized nanobentonite was achieved 96.777% while unmodified bentonite adsorbed 68.25% of TCP in equilibrium time of 3 h. The experimental data of adsorption indicated more conformity with the pseudo-second-order and Langmuir isotherm models. As a deduction, nanobentonite with high adsorption capacity was prepared from bentonite mines of Iran and magnetized by Fe₃O₄ leading to easy and fast separation of nanocomposite TCP from the solution.

A new biodegradtion method for removal of phenol and its derivatives has been considered. In this study the biochemical pathway involved in degradation of phenol through Pseudomonas aeruginosa bacterial cells which are immobilized on graphene oxide (GO) has been investigated. Since phenol is a toxic substance and eliminating it through a biological method is difficult, the phenol removal ability of the bacterial cells of P. aeruginosa has been considered in comparison with phenol adsorption on graphene oxide as a nanostructured adsorbent and P. aeruginosa supported on GO as a new biochemical adsorbent. For this purpose, graphene oxide was initially synthesized using the modified Hummer’s method and the bacterial strain was supported on GO. Scanning electron microscopy was employed to identify their morphology and structure. Also surface functional groups were initially analyzed by FTIR. The variables involved in the phenol removal process including phenol initial concentration, adsorbent dosage, temperature. The best removal efficiency of the bacteria was carried out at optimum conditions of pH 7, biosorbent dose of 0.01 g and phenol initial concentration of 3 ppm after 45 min of contact time at 25°C and up to 55% of phenol was removed. Using 0.01 g of GO and using 0.01 g of P. aeruginosa/GO attained to this removal efficiency at pH 7 after 60 and 45 min. of contact time, respectively, whereas the removal efficiency of the modified biochemical adsorbent of P. aeruginosa/GO was up to 92% at pH 3 after 45 min. of contact time. At the same condition phenol degradation using free cells of P. aeruginosa and using GO nanoparticles were 10.15 and 88.63%, respectively. Pseudo-second order kinetics described the biodegradation of phenol by P. aeruginosa supported on GO.

The high efficiency of the process of water purification from Fe(III) hydroxo-compounds by microfiltration tubular ceramic membrane based on clay minerals has been shown. This water purification process was developed by Dumanskii Institute of Colloid and Water Chemistry (ICWC), National Academy of Science of Ukraine. The effect of the initial solution concentration, its pH, working pressure, the process duration, and the presence of Cl, SO₄²⁻ HCO₃⁻, Ca²⁺ and Na⁺ ions on the separation properties of membrane was studied. The total salt content of the solution did not exceed the maximum permissible concentration (MPC) of the total mineralization of drinking water. It was established that Fe(III) solutions with Fe(III) initial concentration of up to ∼170 mg/dm³ could be purified to the Fe(III) MPC level in drinking water at pH_ini 5.0–7.5 and P = 1.0 MPa during the whole process when the membrane specific performance varied in the range 0.28–0.43 m³/(m²·h). As a result of dynamic modification by Fe(III) hydroxo-compounds at the minimum solution pH_ini 2.8, the membrane retained 33.8% of Ca²⁺ ions, i.e. acquired the ultrafiltration properties. The presence in solution of Cl⁻, SO₄²⁻, and HCO₃⁻ ions, each in the amount of 200 mg/dm³, and Ca²⁺ and Na⁺ ions in the amount of 150 and 236 mg/dm³, respectively, practically did not affect the retention of Fe(III) hydroxo-compounds by ceramic membrane. Since such membranes are cheaper than similar membranes based on oxide ceramics and not inferior to them in terms of the efficiency and can work in most severe conditions, they can be used in practice for the purification of the surface and underground natural waters from Fe(III) hydroxo-compounds, including compounds of various classes, such as chloride, sulfate, hydrocarbonate (carbonate), and mixed type. In addition, they can be applied in local installations for pretreatment of drinking water.

Increasing demands to the quality of drinking water necessitate the search for environmentally friendly and effective methods of its disinfection and purification. The purpose of this work was to study the disinfecting activity of chitosan (ChTS) obtained from natural polymer chitine in relation to E. coli and C. albicans depending on the physicochemical parameters of medium. It has been established that the degree of inactivation of E. coli culture does not depend on the type of ChTS used in this study: high-molecular ChTS₁ (molecular weight (Mw) = 100–300 kDa) and low-molecular ChTS₂ (Mw = 50–60 kDa) with the deacetylation degree of 95 and 75–85%, respectively. In the case of C. albicans, high-molecular weight ChTS with deacetylation degree of 95% is a more effective disinfecting agent. The highest degree of C. albicans inactivation by using ChTS₁ is achieved in a weak acid medium (pH 5.0), while at pH 8.5 the disinfecting effect is negligible. For the first time, a significant contribution of the process of flocculation of microorganisms by chitosan to the total effect of water disinfection has been shown that is especially pronounced at relatively short contact periods (< 1 h) of the culture with chitosan. It is shown that the presence of impurities of an organic and inorganic nature in water reduces both the disinfecting and flocculating effects of polysaccharide in relation to the microbiological objects. It is, probably, associated with the competing activity of these impurities on the interaction of ChTS molecules with microorganisms. The attained results confirm that C. albicans is a more reliable test object of disinfection processes as compared to E. coli that is of practical importance.

The dynamics of sea water self-purification processes in the water area of the Karadag Nature Reserve during five years after the emergency discharges of sulfur and oil products to the Black Sea has been studied. The toxicity of aquatic environment was estimated by the biotesting method based on using saltwater crustaceans: Artemia salina species from the Branchiopoda order. The rate of self-purification processes in surface and deep levels of sea water was established. The ecological significance of self-purification for restoring the quality of marine aquatic environment was specified. The sea water self-purification mechanisms occurring as a result of mechanical, physicochemical and biological processes are studied. It has been revealed that the incoming pollutants are diluted by marine water of the Black Sea, suspended substances gradually settle down to the bottom, while the organic substances are subjected to oxidation at the expense of oxygen dissolved in water. These processes result in organic substances gradually being mineralized by their disintegration into simpler substances. It must be underlined that a complex of biocenoses formed by different hydrobionts takes part in self-purification processes. The majority of them are also directly involved in decontamination of sea from bacterial contaminants, including pathogenic microbes. The mechanism of antibacterial action of hydrobionts is sufficiently diversified. Some of them absorb bacteria for feeding, others cause the cell lysis, and the third release the antibacterial agents into environment. Different type relationships are formed between the bacterial population and other hydrobionts. The predominant types, besides trophic, are metabiosis and antagonism. The biochemical activity of hydrobionts is a dominant process in self-purification of marine ecosystem. The conclusions are made about the need of monitoring the sea water quality by using the methods of biotesting on animal and plant test-organisms of different trophic levels.

The purification of wastewater through the use of the plants (phytoepuration) was used in different areas and under various climates; it was tested successfully for organic pollution, for the elimination of phosphorus pollution, nitrogen pollution, metals, and for the destruction of the pathogenic germs. This study reports the monitoring of purifying performances of three plants, which show a good acclimatization in arid climate: Typha latifolia, Juncus effusus and Cyperus papyrus. The monitoring was carried out during one year from December to November in the southern Algeria. The experimental pilot set-up consists of four plastic barrels capacity of 130 L, filled from the bottom upwards to 45 cm thickness by gravel and 10 cm by sand, with opening located at 5 cm below the sand to avoid any overflow of water. Three barrels were planted with young stems of the studied species with the coverage of 36 stems/m², and the fourth barrel remained unplanted to serve as reference object. 30 L of wastewater which have undergone primary treatment at the purification station of Kouinine (north the town of El-Oued) was supplied to each barrel once a week. The flow occurred by percolation through the substrate. The residence time of water is 5 days. Treated water is recovered by a tap placed in bottom of the barrel. With the three tested plants, very satisfactory outputs were obtained for particulate and organic pollution, where the decrease rates of reached 96% for suspended matter (SM), 89% for the Chemical Oxygen Demand (COD), and 87% for the Biological Oxygen Demand (BOD₅). The elimination of nitrogen and phosphorous pollution resulted in decreasing rates of 94% for nitrates and 95% for orthophosphates. The planted bed of Juncus effusus gives the best outputs for the elimination of organic and nitrogen pollution. However, the planted bed of Cyperus papyrus is the most appropriate for the phosphorous pollution. In addition, the elimination of the organic pollutants decreases in summer; never the less the output of purification remains higher than 68% for all seasons.