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Chelate-assisted phytoremediation
No full textPhytotechnologies have showed potential for sustainable and low-cost use in remediation of contaminated lands. In order to increase effectivness of the phytoremediation process on contaminated sites assisted phytoremediation techniques are developed. One of such procedures is use of chelating agents, able to effectively mobilize metals into the soil solution and bioavailable forms, where they can consequently be uptaken by selected plant species. Various types of chelates, both synthetic and natural, can be used in this process. Chelate-assisted phytoremediation process includes interactions between soil, targeted element(s), chelate and plant in complex processes of solution and transport of elements from soil and their uptake and translocation in plants. Different researches acknowledged efficient element uptake from contaminated soils into selected plant species accompanied with use of adequate chelating agents, especially for sites with low initial mobility of contaminants
Microstructure as an essential aspect of EN AW 7075 aluminum alloy quality influenced by electromagnetic field during continuous casting process
No full textMicrostructure assessment is crucial for the design and production of high-quality alloys such as cast aluminum alloy ingots. Along with the effect of a more homogeneous microstructure to result in much better mechanical properties, better as-cast alloy quality indicates a higher efficiency of the aluminum alloys production process. During the aluminum alloy solidification process many microstructural defects can occur, which deteriorate the mechanical properties and hence decrease the usability of such an ingot. Application of the electromagnetic field during the vertical continuous casting process significantly reduces occurrence of these defects. In the present study, EN AW 7075 alloy samples were cast with and without application of an electromagnetic field and examined regarding the microstructure, electrical conductivity, and changes in the phase composition. The obtained results clearly show that it is possible to decrease or avoid casting defects by the electromagnetic field application as verified by the microstructure characterization and quantification, electrical conductivity tests and differential thermal analysis (DTA)
The clay preliminary testing from municipality area of Rekovac
No full textOn the territory of Rekovac municipality, geological research has discovered clay deposit "Oparić". The sample was taken from the well core with 9m depth, then stirred with water and sifted by wet process on a sieve with 0,063mm opening. It was obtained 71% of reflections (class + 0,063mm) and 29% of sieves (class -0,063mm). The chemical and X-ray analysis of the class -0,063mm was done. The results showed there is increased content of iron in the form of Fe2O3, which reduces the clay quality. Further research should focus on finding the iron removing possibility by magnetic concentration
Adsorption of ibuprofen by surfactant modified kaolin
No full textIn this paper, results of ibuprofen (IBU) adsorption by organokaolins obtained by modification of the natural kaolin (KR) with surfactant - hexadecyltrimethyl ammonium bromide (H) are presented. Two different amounts of surfactant were used for modification of KR (50 and 90% of kaolin’s cation exchange capacity). Samples are denoted as HKR-50 and HKR-90. Adsorption of IBU on organokaolins was investigated with different initial drug concentrations (2 – 20 mg/L) in phosphate buffer at pH 7. Compared with KR which has no affinity to adsorb IBU, modification of KR with H improved adsorption of this drug. Results showed that adsorption of IBU increased with increasing of the amount of surfactant in organokaolins as well as with increasing of the initial concentration of the drug in solution. Adsorption of IBU by both adsorbents followed nonlinear isotherms and from the Langmuir model, the maximum adsorption capacities were 2.05 mg/g for HKR-50 and 3.12 mg/g for HKR-90
Thermodynamic Data Analysis of Sodium Carbonate to Bicarbonate Conversion Reaction
No full textDuring mechanical activation, the energy of treated material is raised to a higher level that
can lead to the chemical transformation of the activated material. This is the point that should
be considered as a phenomenon of the mechanochemical transformations appearing as a
result of mechanical activation. Sodium carbonate as a substance that is often subjected to
mechanochemical synthesis was mechanically activated in this study.Sodium carbonate is
also a well-known material for being used as a good sorbent of carbon dioxide from the
atmosphere, and as such has gained increasing importance in environmental protection. The
conversion reactions of sodium carbonate to sodium bicarbonate under the specified
environment of carbon dioxide and moisture were studied, and the thermodynamic data such
are changes in enthalpy, entropy, and Gibbs energy at the temperature range of 0-160 ° C are
given
Valorization of miscanthus biomass for the production of effective adsorbent materials through hydrothermal carbonization
No full textHydrothermal carbonization (HTC) of biomass takes place in a closed reactor at temperatures between 180 - 260° C and self-sustained pressure using the influence of subcritical water as a reaction medium. In most cases, treatment duration is within the range of 1-24 h. The outcomes of the process are, a solid material with a higher carbon content, called hydrochar and the residual HTC wastewater. Due to their surface structure and tunable properties, hydrochars have been applied as been applied as solid fuels, soil conditioners and adsorbents1).
Miscanthus giganteus, a perennial purpose-grown crop, has been primarily used as an energy source. However, with low bulk density and moisture and significant transportation costs, thermochemical pretreatment of this feedstock has been suggested as the best way to overcome these issues and to increase its use-value. Besides, miscanthus is characterized by a very low ash content and this attribute is advantageous for HTC2).
The scope of this work was to offer new insights into the application of miscanthus hydrochars as adsorbent materials. The main objectives were the following: a) valorization of Miscanthus giganteus for the production of an added-value material (adsorbent) at different HTC temperatures and a short residence time b) application of the 'as produced' hydrochars in the adsorption of Cu2+ and NH4+ c) investigation of the influence of the production temperature and correlation of the process severity to the properties and adsorption behaviour of the samples
Efficient adsorption of lead ions from aqueous solution using Fe/Mg modified grape pomace hydrochar
No full textWithin this study, the potential application of grape pomace hydrochar as a potential adsorbent of lead ions from aqueous
solutions will be investigated for the first time. For preparation of hydrochar, the grape pomace was hydrothermally carbonized in aqueous medium at 220 °C within 1 h. Obtained material was further modified with Mg and Fe salts in order to improve its adsorption properties. Preliminary adsorption results showed that the modified hydrochar exhibited significantly higher adsorption capacity (139.5 mg g-1) compared to the unmodified one (27.8 mg g-1). Further examination of the effects of different adsorption parameters (initial pH value and contact time) using modified and unmodified hydrochar, defined
their optimum values for the most effective lead removal. The obtained results showed that the most efficient removal of lead ions occurs in solutions with pH 5. Furthermore, the examination of the influence of time on the adsorption processdemonstrated that in the beginning the adsorption takes place quickly. The reason for this is the large number of availableactive centres on the hydrochar surface that can bind lead ions. However, as the number of these centres is occupied by a longer contact time, the binding rate decreases and after 240 minutes the equilibrium is reached. Kinetic models of pseudo-first and pseudo-second order were applied to the results of the influence of contact time. The kinetic study implied that the removal of lead ions on modified hydrochars follows pseudo-second order model. This model assumes a chemical interaction between
lead ions and groups on the surface of hydrochar as the main binding mechanism. Based on the above it can be concluded thatthe hydrothermal carbonization is very efficient technology for conversion of waste biomass into highly valuable products. In order to examine in more detail the binding mechanism and the process of metal adsorption using modified hydrochars, additional analyzes will be part of our future research
Microplastics in wastewater
No full textMasovna upotreba plastike u konzumerističkom životnom stilu prouzrokovala je problem koji izumitelji ovih polimera nisu mogli predvideti. Otkriće mikroplastike kao polutanta prisutnog u životnoj sredini postalo je globalna briga i rezultiralo intenzivnom istraživanju u ovoj oblasti. Mikroplastika je definisana kao bilo koji deo plastike sa pre čnikom od 100 nm do 5 mm. Mikroplastika je svuda oko nas, ima je u kozmetičkim proiz vodima, vlaknima odeće, vodi i hrani, a pronađena je čak i u artičkom ledu. U ovom pre glednom radu biće opisano zašto se sumnja da su postrojenja za prečišćavanje otpadnih voda (PPOV) značajni tačkasti izvori ispuštanja mikroplastike u vodenu sredinu.The frequent usage of plastics in the consumer lifestyle has caused a problem that
inventors of these polymers could not have foreseen. The discovery of microplastics as a pollutant present in the environment has become a global concern and has resulted in intensive research in this area. Microplastic is defined as any part of plastic with a diameter of 100 nm to 5 mm. Microplastics are all around us, in cosmetics, fibers of our clothes, water, and food, and it is even found in arctic ice. This review will describe why wastewater treatment plants (WWTPs) are suspected to be significant point sources of microplastic discharges into the aquatic environment
