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Treatment of mine wastewater by adsorption on fly ash
No full textBakar je jedan od najzastupljenijih metala u industriji zbog svoje najšire primene u poređenju sa ostalim obojenim metalima. Tokom procesa eksploatacije bakra stvara se velika količina rudničkih otpadnih voda. Zbog toga postoji sve veće interesovanje za rešavanje ekoloških pitanja industrije rudnika bakra. Hemijski sastav rudničkih otpadnih voda je složen i zavisi od hemijskog sastava rude koja se izlužuje tokom eksploatacije. Leteći pepeo je vrsta industrijskog otpada koji može da izazove višestruke ekološke probleme. S druge strane, zbog velike poroznosti i specifične površine, kao i drugih jedinstvenih karakteristika, leteći pepeo se takođe može koristiti kao jeftin i visoko efikasan adsorbens za prečišćavanje rudničkih otpadnih voda. U ovom radu leteći pepeo iz termoelektrane bez prethodnog tretmana i peletiziran korišćen je za sorpciju bakra iz otpadne vode. Rezultati su pokazali da je leteći pepeo efikasan sorbent bakra pri čemu su pelete imale tri puta veći adsorpcioni kapacitet u odnosu na mikronizirani pepeo.Copper is one of the most present industrial metals due to its wide application compared to other non-ferrous metals. During the mining process of copper exploitation, large amount of mine waste water is generated. Therefore, there is a growing interest in solving the environmental issues of the copper mine industry. The chemical composition of these mine waste waters is complex and depends on the chemical composition of the ore that leaches during the exploitation. Fly ash is a type of industrial waste that can cause multiple environmental problems. On the other hand, owing to its high porosity, large specific surface area, and other unique characteristics, fly ash can also be used as a low-cost and high efficient adsorbent for treatment of mine waste waters. In this paper, fly ash from a thermal power plant without prior treatment and pelletized was used for sorption of copper from wastewater. The results showed that fly ash was an efficient copper sorbent, whereby the pellets had three times higher adsorption capacity compared to micronized fly ash
Novi postupak sinteze amino i epoksi derivata taninske kiseline i lignina za proizvodnju epoksilnih smola na bioobnovljivoj osnovi
No full textLaboratorijski razvijena metoda zasnovana na veštačkim neuronskim mrežama za predikciju svojstava cementnih veziva na bazi mehano-aktiviranog pirofilita
No full textVermiculite enriched by Fe(III) oxides as a novel adsorbent for toxic metals removal
No full textExpanded vermiculite (EV) was modified by deposition of different spinel ferrite composites on the outer surface of EV 2:1 layers in order to improve its adsorptive properties. Modifications were made by deposition of: magnetite, manganese ferrite, cobalt ferrite and chromium oxide/hematite. The characterization of modified materials was performed by: scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) methodology, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), magnetization measurements, as well as determination of cation exchange capacity (CEC) and pH point of zero charge (pHPZC). Obtained samples were used as adsorbents for Pb2+, Ni(2+)and Cd2+ ions from an aqueous solution in a batch system. Results showed that adsorption capacity was strongly dependent on physical and chemical changes induced by specific chemical modification. Hydrothermally produced manganese and cobalt ferrites caused significant surface changes and altered the interlayer cation balance. Among the others, EV-Mn/Co-ferrite(s) samples possessed the highest adsorption capacity towards Ni2+ (33.06 mg g(-1)), along with an increase of the CEC. Freundlich's adsorption isotherm model provided the best fit of obtained experimental data, while kinetic studies showed that the adsorption rate follows the pseudo second-order model, implying heterogeneous adsorbents surface. Thermodynamic and kinetic parameters indicated that the mechanism of cations removal efficacy was dominantly followed by the ion exchange. This study confirmed that doped ferrites, produced by solvothermal method, improve surface properties of EV and increase adsorption potentials towards heavy metals
The Thermophysical Properties of Primary Phase in Lithium Germanium Phosphate Glass
No full textThe selected lithium germanium-phosphate glass was prepared by a conventional melt-quenching technique. The XRD method was employed to confirm the glass was obtained and to reveal crystalline phases during heat treatment. The dilatometry (DIL), differential thermal analysis (DTA), and differential scanning calorimetry (DSC) were used to determine the characteristic temperatures and enthalpies of crystallization and melting of the crystalline phase. The DTA and DIL were used to obtain the viscosity curves by applying the VogelFulcher-Tammann (VFT) equation
Application of Surfactant Modified Natural Zeolites for the Removal of Salicylic Acid-A Contaminant of Emerging Concern
No full textThis work aimed to test composites (surfactant modified zeolites prepared by treatment of natural zeolites-clinoptilolite (IZ CLI) and/or phillipsite (PHIL75)-rich tuffs with two different amounts of cationic surfactants: cetylpyridinium chloride (CPyCl) and Arquad(R) 2HT-75 (ARQ)) for the adsorption of salicylic acid (SA)-a common contaminant of emerging concern. Adsorption of SA was studied at different initial drug concentrations (in the range of 2-100 mg/L) in water solution. The Langmuir isotherm model showed the highest adsorption was achieved by bilayer composite of IZ CLI and CPyCl-around 11 mg/g. Kinetic runs were performed by using the initial drug concentration of 20 mg/L in the time interval from 0 to 75 min and pseudo-second order had good correlation with experimental data. The influence of the four different temperatures on the SA adsorption was also investigated and thermodynamic parameters suggested that the adsorption drug onto composites is an exothermic and nonspontaneous process, followed by the decrease of randomness at the solid/liquid interface during the adsorption. Zeta potential and Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) had been performed for the characterization of composites after adsorption of SA confirming the presence of the drug at composite surfaces
Structure and Strength of Isothermally Heat-Treated Medium Carbon Ti-V Microalloyed Steel
No full textIsothermal transformation characteristics of a medium carbon Ti-V microalloyed steel were investigated using light microscopy, scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), and by uniaxial compressive testing. Samples austenitized on 1100 degrees C were isothermally treated in the range from 350 to 600 degrees C and subsequently water quenched. The final microstructure of the samples held at 350 degrees C consisted of bainitic sheaves and had compressive yield strength, approximately from 1000 MPa, which is attributed to high dislocation density of low bainite. At 400 and 450 degrees C, acicular ferrite became prevalent in the microstructure. It was also formed by a displacive mechanism, but the dislocation density was lower, leading to a decrease of compressive yield strength to approximately 700 MPa. The microstructure after the heat treatment at 500 degrees C consisted of coarse non-polygonal ferrite grains separated by pearlite colonies, principally dislocation free grains, so that the compressive YS reached a minimum value of about 700 MPa. The microstructure of the samples heat-treated at 550 and 600 degrees C consisted of pearlite and both grain boundary and intragranular ferrite, alongside with some martensite. After 600 s, austenite became stable and transformed to martensite after water quenching. Therefore, the presence of martensite increased the compressive YS to approx. 800 MPa
Characterization of Tamnavaclay by X-ray powder diffraction method
No full textThe X-ray powder diffraction method on a polycrystalline sample is one of the basic methods used in the characterization of aluminosilicate minerals.The clay minerals represent a complex system, in which more than one phase is present.The main problems in analysis of clay minerals is weak crystallinity, preferential orientation, as well as the appearance of asymmetry.In this paper are presented the results of analysis of smectic type clay from Tamnava area. For investigation was use the method of X-ray powder diffraction and SEM analysis
Environmental-friendly modified natural zeolites as sorbents for in situ remediation of mercury-contaminated soil in Idria region, Slovenia
No full textToxicity Characteristic Leaching Procedure (TCLP) was applied to mercury- contaminated soil from the Idrija region, Slovenia to evaluate the potential soil toxicity. The
TCLP test was performed with and without the addition of natural zeolite, iron(III)-modified
zeolite or sulphur-impregnated zeolite. Results showed that the soil is extremely polluted and
represents hazardous waste. The addition of zeolites significantly reduces the concentration of
leached Hg, whereby the most satisfactory results being achieved with sulphur-impregnated
zeolite, making it as a potential sorbent for in situ remediation of mercury-contaminated soil
Thermal Decomposition and Kinetics of Pentlandite-Bearing Ore Oxidation in the Air Atmosphere
No full textThe roasting of sulfide ores and concentrates is one of the most important steps in pyrometallurgical metal production from primary raw materials, due to the necessity of excess sulfur removal, present in the virgin material. Pentlandite is one of the main sources for nickel pyrometallurgical production. The knowledge of its reaction mechanism, products distribution during oxidation and reaction kinetics is important for optimizing the production process. Raw pentlandite-bearing ore from the Levack mine (Ontario, Canada) was subjected to oxidative roasting in the air atmosphere. A chemical analysis of the initial sample was conducted according to EDXRF (Energy-Dispersive X-ray Fluorescence) and AAS (Atomic Adsorption Spectrometry) results. The characterization of the initial sample and oxidation products was conducted by an XRD (X-ray Diffraction) and SEM/EDS (Scanning Electron Microscopy with Energy Dispersive Spectrometry) analysis. Thermodynamic calculations, a phase analysis and construction of Kellogg diagrams for Ni-S-O and Fe-S-O systems at 298 K, 773 K, 923 K and 1073 K were used for proposing the theoretical reaction mechanism. A thermal analysis (TG/DTA-Thermogravimetric and Differential Thermal Analyses) was conducted in temperature range 298-1273 K, under a heating rate of 15 degrees min(-1). A kinetic analysis was conducted according to the non-isothermal method of Daniels and Borchardt, under a heating rate of 15 degrees min(-1). Calculated activation energies of 113 kJ mol(-1), 146 kJ mol(-1) and 356 kJ mol(-1) for three oxidation stages imply that in every examined stage of the oxidation process, temperature is a dominant factor determining the reaction rate