The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform
E. Suoninen - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the Ethyl Xanthate adsorption layer on galena (PbS) by synchrotron radiation excited photoelectron spectroscopy
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999Co-Authors: I. Kartio, K Laajalehto, E. SuoninenAbstract:Abstract Utilization of synchrotron radiation excitation in photoelectron spectroscopy (SR-XPS) of solid surfaces provides a significant improvement in surface sensitivity of the method. It has recently been shown that almost an order of magnitude increase in relative intensity of the sulfur 2p signal from the very first atomic layer of a sulfide can be achieved by using SR instead of conventional AlKα or MgKα X-rays for photoelectron excitation. In this work, SR-XPS was applied to characterize the Xanthate layer adsorbed on galena in 10−4 M Potassium Ethyl Xanthate solution (pH 9.2) in equilibrium with air. Chemisorption of Xanthate radicals rather than formation of bulk lead Ethyl Xanthate was observed. Prolonged irradiation of the sample by the SR beam was observed to decompose the adsorption layer. Means to avoid radiation damage during the SR-XPS measurement is discussed.
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Surface analysis of pyrite applying ESCA
Fresenius' Journal of Analytical Chemistry, 1993Co-Authors: R. Szargan, S. Karthe, E. SuoninenAbstract:X-ray photoelectron spectroscopy (ESCA) has been applied to investigate the adsorption of Xanthate on pyrite immersed in Potassium Ethyl Xanthate solution at different pH values. The Xanthate adsorption complex on the pyrite surface was confirmed as the precursor of dixanthogen.
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XPS studies of Xanthate adsorption on pyrite
Applied Surface Science, 1992Co-Authors: R. Szargan, S. Karthe, E. SuoninenAbstract:Abstract X-ray photoelectron spectroscopy (XPS) studies have been carried out on the reactions between natural pyrite with Cu(II) and Xanthate ions in air-saturated solutions. The Cu 2p binding energies point out that Cu(II) ions are inserted into the pyrite surface during the activation changing their oxidation state to Cu(I). Chemical shifts and intensity variations of the C 1s, O 1s and Fe 2p spectra provide evidence that a Xanthate surface species on pyrite is formed in Potassium Ethyl Xanthate solutions with 6 ≤ pH
Paolo Plescia - One of the best experts on this subject based on the ideXlab platform.
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study of galena Potassium Ethyl Xanthate system by x ray diffractometry and scanning electron microscopy
Applied Surface Science, 1993Co-Authors: Paolo PlesciaAbstract:Abstract The mechanism of fixation of Potassium Ethyl Xanthate at low concentration on lead sulphide has been investigated with X-ray diffraction and scanning electron microscopy. The results show that from the first moment of reaction there is nucleation and crystallization of Pb-Ethyl-Xanthate salts and this phenomenon starts from small areas on the surface of PbS. The kinetics of reaction depends on some parameters, like concentration of solution and temperature, but also on PbS surface state, in particular on oxidation state.
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Study of galena/Potassium Ethyl Xanthate system by X-ray diffractometry and scanning electron microscopy
Applied Surface Science, 1993Co-Authors: Paolo PlesciaAbstract:Abstract The mechanism of fixation of Potassium Ethyl Xanthate at low concentration on lead sulphide has been investigated with X-ray diffraction and scanning electron microscopy. The results show that from the first moment of reaction there is nucleation and crystallization of Pb-Ethyl-Xanthate salts and this phenomenon starts from small areas on the surface of PbS. The kinetics of reaction depends on some parameters, like concentration of solution and temperature, but also on PbS surface state, in particular on oxidation state.
Wiesław Wójcik - One of the best experts on this subject based on the ideXlab platform.
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Influence of Ethyl Xanthate on the wettability and surface free energy of galena
Applied Surface Science, 1997Co-Authors: Bronisław Jańczuk, Anna Zdziennicka, Wiesław WójcikAbstract:Abstract The contact angles of water (W), glycerol (G), formamide (F), diiodomethane (D) and 1,1,2,2-tetrabromoethane (T) were measured on a non-oxidized and oxidized surface of galena previously covered with a Potassium Ethyl Xanthate film formed from aqueous solutions at different concentrations. Then, using the obtained values of the contact angle, the Lifshitz–van der Waals component and electron-acceptor and electron-donor parameters of the Lewis acid–base component of the surface free energy of galena covered with Ethyl Xanthate film were calculated from the modified Young equation. It was found that the surface free energy of the galena/Ethyl Xanthate film depends on the way of galena surface treatment after adsorption of Ethyl Xanthate on its surface and results from both apolar and polar intermolecular interactions. The contribution of these interactions in the surface free energy of galena depends on the concentration of Potassium Ethyl Xanthate solution used for film formation and the state of the galena surface (non-oxidized or oxidized). With the increase of Ethyl Xanthate concentration in the solution from which the film was formed, the Lifshitz–van der Waals component increases or decreases a little depending on whether or not the surface galena, after adsorption of Ethyl Xanthate, was washed by Ethyl ether. In all cases, the electron-acceptor parameter of the acid–base component is considerably smaller than the electron-donor one and practically does not depend on the concentration of the Potassium Ethyl Xanthate solution in contact with galena. The changes of the electron-donor parameter of the acid–base component depend on the state of the galena surface, the concentration of the Potassium Ethyl Xanthate solutions and the way of galena surface treatment after adsorption. It is interesting that the total surface free energy, both of non-oxidized and oxidized galena, does not practically depend on the concentration of Potassium Ethyl Xanthate in aqueous solution from which the film was formed.
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Correlation between surface free energy and floatability of galena with Potassium Ethyl Xanthate
Journal of Adhesion Science and Technology, 1996Co-Authors: Bogdan Biliński, Wiesław WójcikAbstract:From the maximal extrapolated film pressure πmax values for n-octane and n-propanol, the dispersion and non-dispersion components of the surface free energy of galena precoated with Potassium Ethyl Xanthate (collector) were estimated and they were then correlated with the floatability of galena. The collector layer deposited by methanol evaporation did not produce any significant changes in the surface free energy of galena. Polymolecular adsorption of the collector occurred from aqueous solution. The adsorbed collector layer of ~8 statistical monolayers in thickness produced a considerable decrease in the dispersion component of the surface free energy and complete disappearance of non-dispersion interactions. At this surface coverage, a certain change in the properties of the adsorbed layer appeared which was probably connected with the formation of polymolecular layers containing dixanthogen. The work of the water adhesion being significantly lower than the work of water cohesion appeared insufficient ...
Bogdan Biliński - One of the best experts on this subject based on the ideXlab platform.
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Correlation between surface free energy and floatability of galena with Potassium Ethyl Xanthate
Journal of Adhesion Science and Technology, 1996Co-Authors: Bogdan Biliński, Wiesław WójcikAbstract:From the maximal extrapolated film pressure πmax values for n-octane and n-propanol, the dispersion and non-dispersion components of the surface free energy of galena precoated with Potassium Ethyl Xanthate (collector) were estimated and they were then correlated with the floatability of galena. The collector layer deposited by methanol evaporation did not produce any significant changes in the surface free energy of galena. Polymolecular adsorption of the collector occurred from aqueous solution. The adsorbed collector layer of ~8 statistical monolayers in thickness produced a considerable decrease in the dispersion component of the surface free energy and complete disappearance of non-dispersion interactions. At this surface coverage, a certain change in the properties of the adsorbed layer appeared which was probably connected with the formation of polymolecular layers containing dixanthogen. The work of the water adhesion being significantly lower than the work of water cohesion appeared insufficient ...
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An investigation of the properties of hydration layers on the surface of galena precoated with Potassium Ethyl Xanthate
Powder Technology, 1991Co-Authors: Bogdan BilińskiAbstract:Abstract Hydration layers on the surface of galena precoated with Potassium Ethyl Xanthate were investigated by differential thermal analysis. The thickness of the hydration layers, their enthalpy and entropy, and the activation energy of adsorbed water were calculated. It was shown that a thick Xanthate coating results in hydration layers with properties very similar to those in bulk water. These properties seem closely correlated with an elimination of non-dispersive interactions of galena surface caused by the Xanthate coating. Comparison of these results with floatability of galena showed that apart from the loosening of the hydration layer structure, another factor played an important role in effective flotation of galena, which may be connected with the presence of dixanthogen at the triple phase interface.
Zs. Szakacs - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Determination of Some Optical and Electrical Properties of Galena Natural Mineral: Potassium Ethyl Xanthate Solution Interface
Russian Journal of Physical Chemistry A, 2017Co-Authors: D. Todoran, R. Todoran, E. M. Anitas, Zs. SzakacsAbstract:This paper presents results concerning optical and electrical properties of galena natural mineral and of the interface layer formed between it and the Potassium Ethyl Xanthate solution. The applied experimental method was differential optical reflectance spectroscopy over the UV–Vis/NIR spectral domain. Computations were made using the Kramers–Kronig formalism. Spectral dependencies of the electron loss functions, determined from the reflectance data obtained from the polished mineral surface, display van Hove singularities, leading to the determination of its valence band gap and electron plasma energy. Time dependent measurement of the spectral dispersion of the relative reflectance of the film formed at the interface, using the same computational formalism, leads to the dynamical determination of the spectral variation of its optical and electrical properties. We computed behaviors of the dielectric constant (dielectric permittivity), the dielectric loss function, refractive index and extinction coefficient, effective valence number and of the electron loss functions. The measurements tend to stabilize when the dynamic adsorption-desorption equilibrium is reached at the interface level.
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Optical luminescence studies of diffusion times at the Potassium Ethyl Xanthate adsorption layer on the surface of sphalerite minerals
IOP Conference Series: Materials Science and Engineering, 2016Co-Authors: R. Todoran, D. Todoran, Eugen Mircea Anitas, Zs. SzakacsAbstract:We propose reflectance measurements as a method for the evaluation of the kinetics of adsorption processes, to compute the diffusion times of the adsorption products at the thin layers formed at the sphalerite natural mineral-Potassium Ethyl Xanthate solution interface. The method is based on the intensity measurement of the reflected monochromatic radiation obtained from the mineral-Xanthate thin layer as a function of time. These determinations were made at the thin layer formed between the sphalerite or activated sphalerite natural minerals with Potassium Ethyl Xanthate, for different solutions concentrations and pH values at constant temperature. Diffusion times of desorbed molecular species into the liquid bring important information about the global kinetics of the ions in this phase during adsorption processes at interfaces. Analysing the time dependence of this parameter one concluded on the diffusion properties of the Xanthate molecule in the solution depending on its concentration and pH, knowing that at the initial time these molecules had a uniform spread. This method enabled us to determine that, in time interval of approximately 35 minutes to achieve dynamic equilibrium in the formation of the interface layer, one had three different kinetic behaviours of our systems. In the first 5-8 min one had highly adsorbent character, the state of equilibrium is followed by low adsorbent properties. Gaining information on the adsorption kinetics in the case of Xanthate on mineral surface leads to the optimization of the industrial froth flotation process.
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Optical luminescence studies of the Ethyl Xanthate adsorption layer on the surface of sphalerite minerals
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2015Co-Authors: R. Todoran, D. Todoran, Zs. SzakacsAbstract:Abstract In this work we propose optical luminescence measurements as a method to evaluate the kinetics of adsorption processes. Measurement of the intensity of the integral optical radiation obtained from the mineral–Xanthate interface layer, stimulated with a monochromatic pulsating optical signal, as a function of time were made. The luminescence radiation was obtained from the thin interface layer formed at the separation surface between the sphalerite natural mineral and Potassium Ethyl Xanthate solution, for different solution concentrations and pH-es at the constant industry standard temperature. This method enabled us to determine the time to achieve dynamic equilibrium in the formation of the interface layer of approximately 20 min, gaining information on the adsorption kinetics in the case of Xanthate on mineral surface and leading to the optimization of the industrial froth flotation process.