The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform

Pawel Kościelniak - One of the best experts on this subject based on the ideXlab platform.

  • seven approaches to elimination of the inherent systematic errors in determination of electrophoretic mobility by capillary electrophoresis
    Analytical Chemistry, 2017
    Co-Authors: Pawel Mateusz Nowak, Michal Woźniakiewicz, Pawel Kościelniak
    Abstract:

    Electrophoretic mobility is a basic parameter that describes the electromigration of an ionized particle, which is used in many fields of analytical and physicochemical science. Its determination by capillary electrophoresis (CE), using a routine method, is intrinsically affected by the generation of Joule heating, entailing a drop in viscosity and possible alteration of the degree of ionization, and also by other commonly overlooked effects: axial electric field distortion and voltage ramping. The objective of this work was to provide the first theoretical overview and experimental comparison of all accessible methods that could be used to prevent these sources of inaccuracy. We have discussed seven independent approaches: (i) extrapolation of mobility to the zero power, (ii) initial buffer resistance-based correction, (iii) rational cooling adjustment, (iv) elimination of the nonthermostated capillary part, (v) inter/extrapolation to the Nominal Temperature, (vi) internal standard-based correction, and ...

Ille Johannes - One of the best experts on this subject based on the ideXlab platform.

  • low Temperature pyrolysis of graptolite argillite dictyonema shale in autoclaves
    2015
    Co-Authors: Galina Sharayeva, Laine Tiikma, Hans Luik, Ille Johannes
    Abstract:

    The results of the systematic experimental study obtained in this work on the effects of Temperature (340–420 °C) and exposure time (0–8h) at Nominal Temperature on the yield of pyrolysis products from Estonian graptolite argillite (GA) generated in autoclaves without any solvent are described. The yields of solid residue (SR), gas, pyrogenetic water (W) and extractable with benzenemix ofthermobitumen and oil (TBO) were estimated. The compound groups of TBO were assessed. The highest yield of TBO, 2.18% on dry GA basis and 13.2% of organic matter (OM) was obtained at Temperature of 420 °C and duration 0.5 h. The main compound groups in TBO obtained at 400 ᵒC are polar hetero-atomic compounds and polycyclic hydrocarbons surpassing 45% and 30% of TBO. The shares of aliphatic and monocyclic hydrocarbons are below 15% of TBO. The yield of W from GA is – about 10-15% of OM. The quantity of OM left in SR after pyrolysis is high, about 65% of OM. The yield of pyrolysis products from GA and the composition of its TBO are compared with those obtained under similar conditions from different oil shales: Estonian Kukersite, US Utah Green River, and Jordanian Attarat.

  • synergy in co pyrolysis of oil shale and pine sawdust in autoclaves
    Journal of Analytical and Applied Pyrolysis, 2013
    Co-Authors: Ille Johannes, Laine Tiikma, Hans Luik
    Abstract:

    Abstract Synergistic effects (Δ) in low Temperature co-pyrolysis of Kukersite oil shale and pine ( Pinus sylvestris ) sawdust were studied in autoclaves in the ranges of blend composition x i  = 0–1 g/g, Nominal Temperature 360–400 °C and duration 2–4 h. The value of Δ was estimated as the difference between the actual yield of pyrolysis products (gas, pyrogenetic water, subsequent extracts into hexane, benzene and tetrahydrofurane, and organic solid residue) and the additive value calculated as linearly proportional to the contributions of the individual components. The amplitude of Δ was explained based on the stability of a new cross-compound A n B formed between the liquid and solid decomposition products of the components. An equimolar synergy reaction ( n  = 1) was proved to result synergies in the yields of the co-pyrolysis products. The extent of synergy was quantitatively evaluated by means of positive and negative values of a new characteristic, synergy factor ( δ ) expressing proportionality between the synergy and product of the shares of the components in the blend (Δ =  δx A x B ). The maximum synergistic increase in the yield of total oil (sum of hexane and benzene extracts), by 21.6%, was revealed for x i  = 0.5 g/g when the primary thermal decomposition of kerogen was not completed (360 °C, 2 h). Lack of synergy prevailed under the optimum conditions for thermobituminization (380 °C, 2–4 h). A decrease in the oil yield from the additive value by 9% was evident when the secondary coke formation from thermobitumen and oil took place (400 °C, 2–3 h).

  • kinetics of kukersite low Temperature pyrolysis in autoclaves
    Journal of Analytical and Applied Pyrolysis, 2009
    Co-Authors: Ille Johannes, Laine Tiikma, Aleksei Zaidentsal, Lea Luik
    Abstract:

    Abstract A systematic experimental study of the effect of reaction time on the low-Temperature pyrolysis of Baltic oil shale (kukersite) in autoclaves at Nominal Temperatures 340–380 °C was carried out. The results show an increase in the yields of gas and coke in time, whereas the yield of the target product, soluble in benzene fraction, has a maximum value (ca. 90%) and the yield of solid residue has a minimum value at a reaction time depending on the Nominal Temperature and heating rate. The process kinetics is described approximately by the first order parallel-consequent decomposition of initial kerogen and thermobitumen formed. A mathematical model is deduced for estimation of the rate coefficients and apparent kinetic constants for formation of gas, soluble in benzene phase, and coke at the low-Temperature pyrolysis and for prediction of the current yields of the products. The experimental and calculated yields of gas, soluble in benzene phase (thermobitumen and oil) and solid residue (coke and not decomposed kerogen) obtained under non-linear increase of Temperature agree satisfactorily.

Lea Luik - One of the best experts on this subject based on the ideXlab platform.

  • kinetics of kukersite low Temperature pyrolysis in autoclaves
    Journal of Analytical and Applied Pyrolysis, 2009
    Co-Authors: Ille Johannes, Laine Tiikma, Aleksei Zaidentsal, Lea Luik
    Abstract:

    Abstract A systematic experimental study of the effect of reaction time on the low-Temperature pyrolysis of Baltic oil shale (kukersite) in autoclaves at Nominal Temperatures 340–380 °C was carried out. The results show an increase in the yields of gas and coke in time, whereas the yield of the target product, soluble in benzene fraction, has a maximum value (ca. 90%) and the yield of solid residue has a minimum value at a reaction time depending on the Nominal Temperature and heating rate. The process kinetics is described approximately by the first order parallel-consequent decomposition of initial kerogen and thermobitumen formed. A mathematical model is deduced for estimation of the rate coefficients and apparent kinetic constants for formation of gas, soluble in benzene phase, and coke at the low-Temperature pyrolysis and for prediction of the current yields of the products. The experimental and calculated yields of gas, soluble in benzene phase (thermobitumen and oil) and solid residue (coke and not decomposed kerogen) obtained under non-linear increase of Temperature agree satisfactorily.

Pawel Mateusz Nowak - One of the best experts on this subject based on the ideXlab platform.

  • seven approaches to elimination of the inherent systematic errors in determination of electrophoretic mobility by capillary electrophoresis
    Analytical Chemistry, 2017
    Co-Authors: Pawel Mateusz Nowak, Michal Woźniakiewicz, Pawel Kościelniak
    Abstract:

    Electrophoretic mobility is a basic parameter that describes the electromigration of an ionized particle, which is used in many fields of analytical and physicochemical science. Its determination by capillary electrophoresis (CE), using a routine method, is intrinsically affected by the generation of Joule heating, entailing a drop in viscosity and possible alteration of the degree of ionization, and also by other commonly overlooked effects: axial electric field distortion and voltage ramping. The objective of this work was to provide the first theoretical overview and experimental comparison of all accessible methods that could be used to prevent these sources of inaccuracy. We have discussed seven independent approaches: (i) extrapolation of mobility to the zero power, (ii) initial buffer resistance-based correction, (iii) rational cooling adjustment, (iv) elimination of the nonthermostated capillary part, (v) inter/extrapolation to the Nominal Temperature, (vi) internal standard-based correction, and ...

Laine Tiikma - One of the best experts on this subject based on the ideXlab platform.

  • low Temperature pyrolysis of graptolite argillite dictyonema shale in autoclaves
    2015
    Co-Authors: Galina Sharayeva, Laine Tiikma, Hans Luik, Ille Johannes
    Abstract:

    The results of the systematic experimental study obtained in this work on the effects of Temperature (340–420 °C) and exposure time (0–8h) at Nominal Temperature on the yield of pyrolysis products from Estonian graptolite argillite (GA) generated in autoclaves without any solvent are described. The yields of solid residue (SR), gas, pyrogenetic water (W) and extractable with benzenemix ofthermobitumen and oil (TBO) were estimated. The compound groups of TBO were assessed. The highest yield of TBO, 2.18% on dry GA basis and 13.2% of organic matter (OM) was obtained at Temperature of 420 °C and duration 0.5 h. The main compound groups in TBO obtained at 400 ᵒC are polar hetero-atomic compounds and polycyclic hydrocarbons surpassing 45% and 30% of TBO. The shares of aliphatic and monocyclic hydrocarbons are below 15% of TBO. The yield of W from GA is – about 10-15% of OM. The quantity of OM left in SR after pyrolysis is high, about 65% of OM. The yield of pyrolysis products from GA and the composition of its TBO are compared with those obtained under similar conditions from different oil shales: Estonian Kukersite, US Utah Green River, and Jordanian Attarat.

  • synergy in co pyrolysis of oil shale and pine sawdust in autoclaves
    Journal of Analytical and Applied Pyrolysis, 2013
    Co-Authors: Ille Johannes, Laine Tiikma, Hans Luik
    Abstract:

    Abstract Synergistic effects (Δ) in low Temperature co-pyrolysis of Kukersite oil shale and pine ( Pinus sylvestris ) sawdust were studied in autoclaves in the ranges of blend composition x i  = 0–1 g/g, Nominal Temperature 360–400 °C and duration 2–4 h. The value of Δ was estimated as the difference between the actual yield of pyrolysis products (gas, pyrogenetic water, subsequent extracts into hexane, benzene and tetrahydrofurane, and organic solid residue) and the additive value calculated as linearly proportional to the contributions of the individual components. The amplitude of Δ was explained based on the stability of a new cross-compound A n B formed between the liquid and solid decomposition products of the components. An equimolar synergy reaction ( n  = 1) was proved to result synergies in the yields of the co-pyrolysis products. The extent of synergy was quantitatively evaluated by means of positive and negative values of a new characteristic, synergy factor ( δ ) expressing proportionality between the synergy and product of the shares of the components in the blend (Δ =  δx A x B ). The maximum synergistic increase in the yield of total oil (sum of hexane and benzene extracts), by 21.6%, was revealed for x i  = 0.5 g/g when the primary thermal decomposition of kerogen was not completed (360 °C, 2 h). Lack of synergy prevailed under the optimum conditions for thermobituminization (380 °C, 2–4 h). A decrease in the oil yield from the additive value by 9% was evident when the secondary coke formation from thermobitumen and oil took place (400 °C, 2–3 h).

  • kinetics of kukersite low Temperature pyrolysis in autoclaves
    Journal of Analytical and Applied Pyrolysis, 2009
    Co-Authors: Ille Johannes, Laine Tiikma, Aleksei Zaidentsal, Lea Luik
    Abstract:

    Abstract A systematic experimental study of the effect of reaction time on the low-Temperature pyrolysis of Baltic oil shale (kukersite) in autoclaves at Nominal Temperatures 340–380 °C was carried out. The results show an increase in the yields of gas and coke in time, whereas the yield of the target product, soluble in benzene fraction, has a maximum value (ca. 90%) and the yield of solid residue has a minimum value at a reaction time depending on the Nominal Temperature and heating rate. The process kinetics is described approximately by the first order parallel-consequent decomposition of initial kerogen and thermobitumen formed. A mathematical model is deduced for estimation of the rate coefficients and apparent kinetic constants for formation of gas, soluble in benzene phase, and coke at the low-Temperature pyrolysis and for prediction of the current yields of the products. The experimental and calculated yields of gas, soluble in benzene phase (thermobitumen and oil) and solid residue (coke and not decomposed kerogen) obtained under non-linear increase of Temperature agree satisfactorily.