Luděk Jelínek - Academia.edu (original) (raw)

Papers by Luděk Jelínek

Solvent Extraction and Ion Exchange, 2021

ABSTRACT Polyoxometalates (POMs) represent a fascinating class of inorganic cluster compounds. Du... more ABSTRACT Polyoxometalates (POMs) represent a fascinating class of inorganic cluster compounds. Due to the almost unlimited possibilities to tailor size, shape and charge of this compound class and to perform various surface functionalization, they are discussed for different applications, especially in the fields of catalysis, material sciences, and biomedicine. In contrast, the systematic study of extraction and sorption properties of POMs has received relatively little attention so far. This review article provides a brief overview of relevant POM structures used for effective and selective phase transfer of metal ions from aqueous into organic media as well as for the development of efficient sorption processes. The use of inorganic-organic POM-based hybrid materials for extraction and sorption processes is also discussed.

Separation Science and Technology, 2017

ABSTRACT The aim of this article is to observe anomalous behaviour of strong acid cation (SAC) ex... more ABSTRACT The aim of this article is to observe anomalous behaviour of strong acid cation (SAC) exchanger in VVER and PWR power plants. This ion exchanger is a part of primary water coolant purification system and shows a non-standard operation in the end of the fuel cycle during high-performance effect. This behaviour consists in process’ changes of potassium cation capture from boric acid solution, which is a major chemical of primary cooling water. The experiments were conducted under laboratory conditions on ion exchanger type DOWEX HCR-S NG and the samples with different concentrations of analytes (K+, NH4+, Li+, H3BO3) were measured. The results confirmed the anomalous behaviour of ion exchanger during high-performance effect when the potassium ions are captured on SAC due to its size and the lack of boric acid in water coolant. Therefore, the potassium hydroxide must be dosed into the primary water to control the content of alkali metals.

Water Environment Research, 2004

The process of electrochemical treatment of a solution after strong basic anion exchanger regener... more The process of electrochemical treatment of a solution after strong basic anion exchanger regeneration was studied. The goal of the study was to reduce the nitrate content in the solution to allow its use in a closed loop. Diaphragmless, flow‐through cells in a recirculation mode with and without a fluidizing bed of inert particles in the interelectrode space equipped with copper (Cu) cathodes and activated titanium anodes were used. The temperature was maintained at 20 ° C. To assess the influence of recirculation of the regenerant solution on the quality of the treated water, the effect of the addition of copper ions to the solution, postelectrolysis cathode treatment, and enhanced mass transfer on the electrolysis results with respect to current efficiency and residual nitrate and nitrite concentration were investigated using an artificial solution. On the basis of the experimental results, a laboratory‐scale unit for selective nitrate removal was designed and constructed that in...

Solvent Extraction and Ion Exchange, 2017

Water contaminated with uranium can be purified by ion exchangers that can be regenerated and reu... more Water contaminated with uranium can be purified by ion exchangers that can be regenerated and reused. The study investigated how mechanical and chemical properties of selected anion exchangers change under the simulated operational conditions. Batch and dynamic column experiments were carried out to estimate the change of total capacity, breakthrough capacity, volume of purified water, pressure drop across the column and the regeneration efficiency. Observed changes include lowering of total capacity and increasing pressure drop because of the mechanical degradation of beads of anion exchangers. The later was confirmed by the measurement of particle size distribution.

Separation Science and Technology, 2016

Separation Science and Technology, 2014

Arsenate sorption onto inorganic and composite inorganic/organic selective sorbents based on ferr... more Arsenate sorption onto inorganic and composite inorganic/organic selective sorbents based on ferric oxide/oxohydroxide was tested under varying concentration of accompanying anions (chlorides, sulfates, phosphates, and silicates). Among the studied anions, phosphates showed the strongest influence on arsenic removal. Ferric oxide based sorbents were also compared to weak and strong base anion exchangers and other metal oxide (ceric oxide, zirconium oxide) based composites under the presence of accompanying anions (chlorides and sulfates). Their performance was comparable to ferric oxide composites. Ferric oxide/oxohydroxide based composites are able to take up arsenates (with capacity of tens of mmol·L−1) even at the presence of 100 mg·L−1 of chlorides and sulfates where the breakthrough capacities of weak and strong base anion exchangers dropped to less than 2% (units of mmol·L−1) of the values obtained in the absence of accompanying anions (hundreds of mmol·L−1).

Fundamentals and Applications of Anion Separations, 2004

The contamination of public drinking-water resources by oxoanions of metals such as Mo, V, W, Ge,... more The contamination of public drinking-water resources by oxoanions of metals such as Mo, V, W, Ge, and As is caused either by industrial activity (i.e., industrial waste waters penetrating without sufficient and proper treatment into surface and/or ground waters) or by the contact of water with metal-bearing ores1 or solid waste materials such as deposits of fly ash. These contaminated waters usually contain trace concentrations (low mg/L level) of metal oxoanions and a large concentration (200–1000 mg/L) of accompanying nonhazardous anions such as chloride, sulfate, and bicarbonate.

Solvent Extraction and Ion Exchange, 2007

ABSTRACT Eu(III) was selectively reduced to Eu(II) at three‐dimensional glassy carbon cathode in ... more ABSTRACT Eu(III) was selectively reduced to Eu(II) at three‐dimensional glassy carbon cathode in 0.01 mol · dm hydrochloric acid medium. Eu(III) reduction took place after all the dissolved oxygen was reduced and then proceeded steadily. Separation of Eu(II) from trivalent rare earths (La, Ce, Sm, Gd, Er, Yb) was carried out using a novel impregnated resin based on bis(2‐ethylhexy1)phosphoric acid. Eu(II) showed much lower affinity towards the resin than the trivalent rare earths and broke through the column readily. Eu of purity higher than 99.8% was yielded. The back‐oxidation of Eu(II) was observed during the sorption and Eu(III) was absorbed onto the resin. Adsorbed light and middle rare earths could be stripped from the loaded resin by 3M hydrochloric acid. Stripping of heavy rare earths (Er, Yb) was problematic.

Solvent Extraction and Ion Exchange, 2006

ABSTRACT Electro‐oxidation of Ce(III) to Ce(IV) in nitric acid media at different anode materials... more ABSTRACT Electro‐oxidation of Ce(III) to Ce(IV) in nitric acid media at different anode materials with high oxygen evolution overpotential was carried out. Ce(IV) nitrato complexes were adsorbed on a novel resin, based on porous silica beads with immobilized polystyrene/DVB copolymer, that was impregnated with tri‐n‐butyl phosphate (TBP). Under the studied conditions, Ce(IV) sorption increased with increasing nitric acid concentration (0.5–6 mol · dm). Oxidation of sorbent by adsorbed Ce(IV) species resulting in Ce(III) release to the solution was observed and thoroughly evaluated. In spite of problems with TBP leakage (12%), column separation of pure Ce(IV) from Y(III) and La(III) was achieved in 6 mol · dm HNO3 at 288 K. Ce(IV) breakthrough capacity was 0.48 mol · kg‐TBP. Column regeneration with 0.1 mol · dm nitric acid yielded Ce solution with purity higher than 99.99 wt.% with respect to La and Y impurities.

Separation Science and Technology, 2009

The possibility of mutual separation of V and W oxoanions from aqueous solution was investigated ... more The possibility of mutual separation of V and W oxoanions from aqueous solution was investigated by elecro-reduction of V(V) to V(IV) in a flow-type electrolyzer combined with column sorption on a selective resin having 1-deoxy-1-(methylamino)-glucitol functional groups. At pH 3, V(V) oxoanion () was reduced to V(IV) cation, which passed into the effluent, whereas W, existing as , was quantitatively

Separation Science and Technology, 2008

Two samples of chemically modified seaweed Ascophyllum nodosum (NS-1 and DS-1) were used for sele... more Two samples of chemically modified seaweed Ascophyllum nodosum (NS-1 and DS-1) were used for selective removal of metal (W, Mo, V, Ge, and Sb) oxoanions. All experiments were carried out by dynamic column sorption. The effects of pH, the concentration of the accompanying anions in the feed solution, and the effect of the flow rate were studied. Tungstate, molybdate, and vanadate were adsorbed extensively. Sorption of Sb(III) anion was notable but the sorption capacity was very low and the desorption was difficult. Sorption of Ge(IV) oxoanion was negligible. Stability of the NS-1 and DS-1 sorbents was limited by, 20 and 25 sorption cycles, respectively.

Separation Science and Technology, 2013

ABSTRACT

Separation Science and Technology, 2010

Two different composite sorbents of chemically modified dealginaded seaweed Ascophyllum nodosum (... more Two different composite sorbents of chemically modified dealginaded seaweed Ascophyllum nodosum (DS-2 and DS-3) were used for the selective removal of metal (W, Mo, and V) oxoanions. All experiments were carried out by dynamic column sorption. The effects of the pH, flow rate and the concentration of the accompanying anions in the feed solution were studied. Sorption of tungstate, molybdate

Reactive and Functional Polymers, 2007

Fibrous sorbents based on polypropylene and viscose fibers grafted with styrene or glycidyl metha... more Fibrous sorbents based on polypropylene and viscose fibers grafted with styrene or glycidyl methacrylate and functionalized with N-methylglucamine were compared with classical polystyrene/DVB bead sorbent with N-methylglucamine functional group. Tests were carried out in dynamic column mode. Model solution of reverse osmosis permeate containing 1.5 mg/L of boron was pumped through 5 mL of sorbent packed in glass column. Fibrous sorbents showed much faster sorption kinetics than bead sorbent, tolerating high specific flow-rates. Compared to bead sorbent, boron regeneration profiles of fibrous sorbents were narrower and they could be successfully regenerated with more diluted hydrochloric acid.

Journal of Rare Earths, 2007

Journal of Rare Earths, 2006

Electro-oxidation of Ce (m) to Ce (Iv) in parallel plate flow type electrolyzer divided with cati... more Electro-oxidation of Ce (m) to Ce (Iv) in parallel plate flow type electrolyzer divided with cation exchange membrane was carried out in nitric acid media at carbon felt anode under galvanostatic conditions. Carbon felt was used as an anode for its high specific surface area and high oxygen evolution overpotential. Pt coated Ti plates were used as cathode and anode current feeder. The oxidation of 1 mol-L Ce (1) solution in 2 mol * L-HN03 was proceeding with a high current efficiency (92%) until about 80% of Ce(1) was oxidized. Then, oxygen evolution, accompanied by terminal voltage jump, took place, lowering current efficiency. Ce(m) was oxidized up to 90% with current efficiency of 6 2 %. In this mode, strong carbon felt anode oxidation was observed. The wear out of carbon felt was 46% in six consequent runs (6 h of operation). After each run, carbon felt surface had to be renewed with slightly alkaline solution to remove carbon oxidation products and ensure regular operational conditions. When anode surface was blocked, oxygen evolution took place from the beginning of electrolysis due to higher actual current density. The wear out of carbon felt anode could be minimized by means of oxygen evolution prevention. In the case when electrolysis had been stopped before oxygen evolution started (at Ce(Iv) conversion of about 80%) , the wear out of anode was less than 2 % during 6 consequent runs (4 h of operation).

Journal of Ion Exchange, 2003

The selective uptake of above mentioned contaminant species was investigated and

Solvent Extraction and Ion Exchange, 2021

ABSTRACT Polyoxometalates (POMs) represent a fascinating class of inorganic cluster compounds. Du... more ABSTRACT Polyoxometalates (POMs) represent a fascinating class of inorganic cluster compounds. Due to the almost unlimited possibilities to tailor size, shape and charge of this compound class and to perform various surface functionalization, they are discussed for different applications, especially in the fields of catalysis, material sciences, and biomedicine. In contrast, the systematic study of extraction and sorption properties of POMs has received relatively little attention so far. This review article provides a brief overview of relevant POM structures used for effective and selective phase transfer of metal ions from aqueous into organic media as well as for the development of efficient sorption processes. The use of inorganic-organic POM-based hybrid materials for extraction and sorption processes is also discussed.

Separation Science and Technology, 2017

ABSTRACT The aim of this article is to observe anomalous behaviour of strong acid cation (SAC) ex... more ABSTRACT The aim of this article is to observe anomalous behaviour of strong acid cation (SAC) exchanger in VVER and PWR power plants. This ion exchanger is a part of primary water coolant purification system and shows a non-standard operation in the end of the fuel cycle during high-performance effect. This behaviour consists in process’ changes of potassium cation capture from boric acid solution, which is a major chemical of primary cooling water. The experiments were conducted under laboratory conditions on ion exchanger type DOWEX HCR-S NG and the samples with different concentrations of analytes (K+, NH4+, Li+, H3BO3) were measured. The results confirmed the anomalous behaviour of ion exchanger during high-performance effect when the potassium ions are captured on SAC due to its size and the lack of boric acid in water coolant. Therefore, the potassium hydroxide must be dosed into the primary water to control the content of alkali metals.

Water Environment Research, 2004

The process of electrochemical treatment of a solution after strong basic anion exchanger regener... more The process of electrochemical treatment of a solution after strong basic anion exchanger regeneration was studied. The goal of the study was to reduce the nitrate content in the solution to allow its use in a closed loop. Diaphragmless, flow‐through cells in a recirculation mode with and without a fluidizing bed of inert particles in the interelectrode space equipped with copper (Cu) cathodes and activated titanium anodes were used. The temperature was maintained at 20 ° C. To assess the influence of recirculation of the regenerant solution on the quality of the treated water, the effect of the addition of copper ions to the solution, postelectrolysis cathode treatment, and enhanced mass transfer on the electrolysis results with respect to current efficiency and residual nitrate and nitrite concentration were investigated using an artificial solution. On the basis of the experimental results, a laboratory‐scale unit for selective nitrate removal was designed and constructed that in...

Solvent Extraction and Ion Exchange, 2017

Water contaminated with uranium can be purified by ion exchangers that can be regenerated and reu... more Water contaminated with uranium can be purified by ion exchangers that can be regenerated and reused. The study investigated how mechanical and chemical properties of selected anion exchangers change under the simulated operational conditions. Batch and dynamic column experiments were carried out to estimate the change of total capacity, breakthrough capacity, volume of purified water, pressure drop across the column and the regeneration efficiency. Observed changes include lowering of total capacity and increasing pressure drop because of the mechanical degradation of beads of anion exchangers. The later was confirmed by the measurement of particle size distribution.

Separation Science and Technology, 2016

Separation Science and Technology, 2014

Arsenate sorption onto inorganic and composite inorganic/organic selective sorbents based on ferr... more Arsenate sorption onto inorganic and composite inorganic/organic selective sorbents based on ferric oxide/oxohydroxide was tested under varying concentration of accompanying anions (chlorides, sulfates, phosphates, and silicates). Among the studied anions, phosphates showed the strongest influence on arsenic removal. Ferric oxide based sorbents were also compared to weak and strong base anion exchangers and other metal oxide (ceric oxide, zirconium oxide) based composites under the presence of accompanying anions (chlorides and sulfates). Their performance was comparable to ferric oxide composites. Ferric oxide/oxohydroxide based composites are able to take up arsenates (with capacity of tens of mmol·L−1) even at the presence of 100 mg·L−1 of chlorides and sulfates where the breakthrough capacities of weak and strong base anion exchangers dropped to less than 2% (units of mmol·L−1) of the values obtained in the absence of accompanying anions (hundreds of mmol·L−1).

Fundamentals and Applications of Anion Separations, 2004

The contamination of public drinking-water resources by oxoanions of metals such as Mo, V, W, Ge,... more The contamination of public drinking-water resources by oxoanions of metals such as Mo, V, W, Ge, and As is caused either by industrial activity (i.e., industrial waste waters penetrating without sufficient and proper treatment into surface and/or ground waters) or by the contact of water with metal-bearing ores1 or solid waste materials such as deposits of fly ash. These contaminated waters usually contain trace concentrations (low mg/L level) of metal oxoanions and a large concentration (200–1000 mg/L) of accompanying nonhazardous anions such as chloride, sulfate, and bicarbonate.

Solvent Extraction and Ion Exchange, 2007

ABSTRACT Eu(III) was selectively reduced to Eu(II) at three‐dimensional glassy carbon cathode in ... more ABSTRACT Eu(III) was selectively reduced to Eu(II) at three‐dimensional glassy carbon cathode in 0.01 mol · dm hydrochloric acid medium. Eu(III) reduction took place after all the dissolved oxygen was reduced and then proceeded steadily. Separation of Eu(II) from trivalent rare earths (La, Ce, Sm, Gd, Er, Yb) was carried out using a novel impregnated resin based on bis(2‐ethylhexy1)phosphoric acid. Eu(II) showed much lower affinity towards the resin than the trivalent rare earths and broke through the column readily. Eu of purity higher than 99.8% was yielded. The back‐oxidation of Eu(II) was observed during the sorption and Eu(III) was absorbed onto the resin. Adsorbed light and middle rare earths could be stripped from the loaded resin by 3M hydrochloric acid. Stripping of heavy rare earths (Er, Yb) was problematic.

Solvent Extraction and Ion Exchange, 2006

ABSTRACT Electro‐oxidation of Ce(III) to Ce(IV) in nitric acid media at different anode materials... more ABSTRACT Electro‐oxidation of Ce(III) to Ce(IV) in nitric acid media at different anode materials with high oxygen evolution overpotential was carried out. Ce(IV) nitrato complexes were adsorbed on a novel resin, based on porous silica beads with immobilized polystyrene/DVB copolymer, that was impregnated with tri‐n‐butyl phosphate (TBP). Under the studied conditions, Ce(IV) sorption increased with increasing nitric acid concentration (0.5–6 mol · dm). Oxidation of sorbent by adsorbed Ce(IV) species resulting in Ce(III) release to the solution was observed and thoroughly evaluated. In spite of problems with TBP leakage (12%), column separation of pure Ce(IV) from Y(III) and La(III) was achieved in 6 mol · dm HNO3 at 288 K. Ce(IV) breakthrough capacity was 0.48 mol · kg‐TBP. Column regeneration with 0.1 mol · dm nitric acid yielded Ce solution with purity higher than 99.99 wt.% with respect to La and Y impurities.

Separation Science and Technology, 2009

The possibility of mutual separation of V and W oxoanions from aqueous solution was investigated ... more The possibility of mutual separation of V and W oxoanions from aqueous solution was investigated by elecro-reduction of V(V) to V(IV) in a flow-type electrolyzer combined with column sorption on a selective resin having 1-deoxy-1-(methylamino)-glucitol functional groups. At pH 3, V(V) oxoanion () was reduced to V(IV) cation, which passed into the effluent, whereas W, existing as , was quantitatively

Separation Science and Technology, 2008

Two samples of chemically modified seaweed Ascophyllum nodosum (NS-1 and DS-1) were used for sele... more Two samples of chemically modified seaweed Ascophyllum nodosum (NS-1 and DS-1) were used for selective removal of metal (W, Mo, V, Ge, and Sb) oxoanions. All experiments were carried out by dynamic column sorption. The effects of pH, the concentration of the accompanying anions in the feed solution, and the effect of the flow rate were studied. Tungstate, molybdate, and vanadate were adsorbed extensively. Sorption of Sb(III) anion was notable but the sorption capacity was very low and the desorption was difficult. Sorption of Ge(IV) oxoanion was negligible. Stability of the NS-1 and DS-1 sorbents was limited by, 20 and 25 sorption cycles, respectively.

Separation Science and Technology, 2013

ABSTRACT

Separation Science and Technology, 2010

Two different composite sorbents of chemically modified dealginaded seaweed Ascophyllum nodosum (... more Two different composite sorbents of chemically modified dealginaded seaweed Ascophyllum nodosum (DS-2 and DS-3) were used for the selective removal of metal (W, Mo, and V) oxoanions. All experiments were carried out by dynamic column sorption. The effects of the pH, flow rate and the concentration of the accompanying anions in the feed solution were studied. Sorption of tungstate, molybdate

Reactive and Functional Polymers, 2007

Fibrous sorbents based on polypropylene and viscose fibers grafted with styrene or glycidyl metha... more Fibrous sorbents based on polypropylene and viscose fibers grafted with styrene or glycidyl methacrylate and functionalized with N-methylglucamine were compared with classical polystyrene/DVB bead sorbent with N-methylglucamine functional group. Tests were carried out in dynamic column mode. Model solution of reverse osmosis permeate containing 1.5 mg/L of boron was pumped through 5 mL of sorbent packed in glass column. Fibrous sorbents showed much faster sorption kinetics than bead sorbent, tolerating high specific flow-rates. Compared to bead sorbent, boron regeneration profiles of fibrous sorbents were narrower and they could be successfully regenerated with more diluted hydrochloric acid.

Journal of Rare Earths, 2007

Journal of Rare Earths, 2006

Electro-oxidation of Ce (m) to Ce (Iv) in parallel plate flow type electrolyzer divided with cati... more Electro-oxidation of Ce (m) to Ce (Iv) in parallel plate flow type electrolyzer divided with cation exchange membrane was carried out in nitric acid media at carbon felt anode under galvanostatic conditions. Carbon felt was used as an anode for its high specific surface area and high oxygen evolution overpotential. Pt coated Ti plates were used as cathode and anode current feeder. The oxidation of 1 mol-L Ce (1) solution in 2 mol * L-HN03 was proceeding with a high current efficiency (92%) until about 80% of Ce(1) was oxidized. Then, oxygen evolution, accompanied by terminal voltage jump, took place, lowering current efficiency. Ce(m) was oxidized up to 90% with current efficiency of 6 2 %. In this mode, strong carbon felt anode oxidation was observed. The wear out of carbon felt was 46% in six consequent runs (6 h of operation). After each run, carbon felt surface had to be renewed with slightly alkaline solution to remove carbon oxidation products and ensure regular operational conditions. When anode surface was blocked, oxygen evolution took place from the beginning of electrolysis due to higher actual current density. The wear out of carbon felt anode could be minimized by means of oxygen evolution prevention. In the case when electrolysis had been stopped before oxygen evolution started (at Ce(Iv) conversion of about 80%) , the wear out of anode was less than 2 % during 6 consequent runs (4 h of operation).

Journal of Ion Exchange, 2003

The selective uptake of above mentioned contaminant species was investigated and