Marco Wenzel - Academia.edu (original) (raw)
Papers by Marco Wenzel
Chemistry – A European Journal, 2021
Abstract The reaction of UO2(OAc)2 ⋅ 2H2O with the biologically inspired ligand 2‐salicylidene gl... more Abstract The reaction of UO2(OAc)2 ⋅ 2H2O with the biologically inspired ligand 2‐salicylidene glucosamine (H2 L1) results in the formation of the anionic trinuclear uranyl complex [(UO2)3(μ3‐O)(L1)3]2− (1 2−), which was isolated in good yield as its Cs‐salt, [Cs]2 1. Recrystallization of [Cs]2 1 in the presence of 18‐crown‐6 led to formation of a neutral ion pair of type [M(18‐crown‐6)]2 1, which was also obtained for the alkali metal ions Rb+ and K+ (M=Cs, Rb, K). The related ligand, 2‐(2‐hydroxy‐1‐naphthylidene) glucosamine (H2 L2) in a similar procedure with Cs+ gave the corresponding complex [Cs(18‐crown‐6)]2[(UO2)3(μ3‐O)(L2)3 ([Cs(18‐crown‐6)]2 2). From X‐ray investigations, the [(UO2)3O(Ln)3]2− anion (n=1, 2) in each complex is a discrete trinuclear uranyl species that coordinates to the alkali metal ion via three uranyl oxygen atoms. The coordination behavior of H2 L1 and H2 L2 towards UO2 2+ was investigated by NMR, UV/Vis spectroscopy and mass spectrometry, revealing the in situ formation of the 1 2− and 2 2−dianions in solution.
ACS Omega, 2021
Developing biosorbents derived from agro-industrial biomass is considered as an economic and sust... more Developing biosorbents derived from agro-industrial biomass is considered as an economic and sustainable method for dealing with uraniumcontaminated wastewater. The present study explores the feasibility of oxidizing a representative protein-rich biomass, brewer's spent grain (BSG), to an effective and reusable uranyl ion adsorbent to reduce the cost and waste generation during water treatment. The unique composition of BSG favors the oxidation process and yields in a high carboxyl group content (1.3 mmol/g) of the biosorbent. This makes BSG a cheap, sustainable, and suitable raw material independent from pretreatment. The oxidized brewer's spent grain (OBSG) presents a high adsorption capacity of U(VI) of 297.3 mg/g (c 0 (U) = 900 mg/L, pH = 4.7) and fast adsorption kinetics (1 h) compared with other biosorbents reported in the literature. Infrared spectra (Fourier transform infrared), 13 C solid-state nuclear magnetic resonance spectra, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis were employed to characterize the biosorbents and reveal the adsorption mechanisms. The desorption and reusability of OBSG were tested for five cycles, resulting in a remaining adsorption of U(VI) of 100.3 mg/g and a desorption ratio of 89%. This study offers a viable and sustainable approach to convert agro-industrial waste into effective and reusable biosorbents for uranium removal from wastewater.
Dalton Transactions, 2021
Single crystal X-ray analyses, solution NMR and EXAFS studies of a series of f-elements metal(iv)... more Single crystal X-ray analyses, solution NMR and EXAFS studies of a series of f-elements metal(iv) complexes of a 4-phosphoryl pyrazolone ligand show essentially the same coordination of the metal ions in solution and in the solid state.
Chemistry Letters, 2021
Recent advances in guanidinium-based receptors are summarized emphasizing the high affinity of th... more Recent advances in guanidinium-based receptors are summarized emphasizing the high affinity of the guanidinium moiety towards certain anions in highly competitive aqueous media. Particularly the in...
Journal of Hazardous Materials, 2021
Spent hydrodesulfurization (HDS) catalysts, containing considerable amount of pollutants and meta... more Spent hydrodesulfurization (HDS) catalysts, containing considerable amount of pollutants and metals including vanadium (V), molybdenum (Mo), aluminum (Al), and nickel (Ni), are considered as hazardous wastes which will result in not only ecosystem damage but also squandering resource. Herein, a process featuring blank roasting-alkaline leaching is proposed to recover spent HDS catalyst. During roasting, low-valence compounds convert to high-valence oxides which can be leached out by NaOH solution. Afterwards, leaching solution is subjected to crystallization to separate metals. The results show that for samples roasted at 650 °C, 97% V, 96% Mo, and 88% Al are leached out at optimal condition; for samples roasted at 1000 °C, selective leaching of 91% V and 96% Mo respectively, are realized, with negligible Al being dissolved. NiO is insoluble in strong alkali leaving in residue. The advantages of this process are that first, the leaching of V, Mo, and Al can be manipulated by controlling roasting conditions, providing flexible process design. Second, leaching solution can be fully recycled. Finally, mild leaching condition and clean separation of V, Mo, and Al is achieved, proving fundamental information for peer researches to facilitate their future research on the development of more efficient and cleaner technologies.
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2017
This micro review covers recent advances in anion recognition, such as selective developments in ... more This micro review covers recent advances in anion recognition, such as selective developments in the receptor design. Applications to which anion receptors can be applied, for example anion extraction and transport, are highlighted.
Minerals Engineering, 2018
In Vietnam, Dzung Quat Refinery disposes about 7300 tonnes of spent fluid catalytic cracking (SFC... more In Vietnam, Dzung Quat Refinery disposes about 7300 tonnes of spent fluid catalytic cracking (SFCC) catalysts per year. The recovery of rare earth metals (La(III), Ce(III),…) contained in SFCC catalysts using acid leaching process has attracted much attention of scientific community. In this study, the effect of alkaline pre-treatment of spent catalysts prior to the acid leaching process on the leaching yield of La(III) was investigated. The results showed that alkaline pre-treatment caused zeolite destruction, which had a positive effect on the leaching of La (III). High leaching yields of La(III), 80% and 86%, were achieved when the SFCC catalysts were pre-treated with NaOH and NH 3 , respectively, before leaching with 2 M HNO 3 solution at 50°C. These results were comparable with the one obtained from the sample that was leached by 7 M HNO 3 at 50°C without the initial alkaline pretreatment. NH 3 pre-treatment significantly enhanced the zeolite destruction in the SFCC catalysts and increased La(III) leaching yield compared to the NaOH pre-treatment. It is likely due to NH 3 interactions with contaminant metals (e.g. Ni, V, and Fe), which were deposited on catalysts during cracking process.
Korean Journal of Chemical Engineering, 2018
Acid leaching and a two-step solvent extraction procedure were developed to produce high purity ... more Acid leaching and a two-step solvent extraction procedure were developed to produce high purity mixture of La and Ce from iron-rich spent FCC catalyst discharged from Dzung Quat refinery (Vietnam). Acid leaching of the spent catalyst with 2 M HNO 3 and a solid-to-liquid ratio of 1/3 at 80 o C in 1 h dissolved almost 90% of La while 12% of Al and 25% of Fe were transferred to the leachate. The extraction of RE metals and main impurities such as Al and Fe by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) was investigated. Experiments showed that it was necessary to remove Fe before extracting RE and the optimum extraction conditions for a high recovery of RE while 0% of Al extraction were pH1, contact time=10 min, and D2EHPA/TBP volume ratio= 4 : 1. At these conditions, the extraction yields of La(III) and Ce(III) were 72% and 89%, respectively. A two-step solvent extraction was developed to achieve a high purity of RE mixture, which included (1) the removal of impurity Fe by 25% (v/v) diisooctyl phosphinic acid (DiOPA) in n-octane for 140 min, (2) the extraction of rare earths by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) in n-octane for 10 min without the need for adjusting the pH of the leaching solution.
International Symposium on Microelectronics, 2013
Aluminum and silicon nitride ceramics show high potent as substrate materials for thick film- / h... more Aluminum and silicon nitride ceramics show high potent as substrate materials for thick film- / hybrid applications in the field of power electronics and microwave technology. A main advantage of AlN is its very high thermal conductivity. Si3N4 has also a thermal conductivity comparable to AlN but higher thermal shock resistance and fracture toughness. Nevertheless, the use of Si3N4 in power electronic packages or heater applications is not achieved due to the lack of suitable connection technology such as thick film pastes. The main challenge for the respective pastes is the adhesion on the substrate. The low thermal expansion (CTE) of about 2.8 ppm/K of Si3N4 and material interactions with the thick film components must be considered in the paste development. Therefore, new glasses and glass-ceramic composites are required. Reason development was performed towards AgPd based thick film heater pastes for Si3N4. The pastes consists of AgPd in a 1:1 ratio, an inorganic filler and a g...
Australian Journal of Chemistry, 2015
Two tripodal ligands, each derived from 1,1,1-tris(hydroxymethyl)ethane and terminated respective... more Two tripodal ligands, each derived from 1,1,1-tris(hydroxymethyl)ethane and terminated respectively by 4-pyridyl (L1) and 2-pyridyl groups (L2), have been synthesised. Competitive seven-metal extraction studies (H2O/CHCl3) incorporating equal concentrations of cobalt(ii), nickel(ii), copper(ii), zinc(ii), silver(i), cadmium(ii), and lead(ii) in the aqueous phase and L1 or L2 in the organic phase showed selective extraction of silver(i) in each case. A parallel solvent extraction experiment involving a related tripodal tris-pyridyl ligand (L3) based on a 1,3,5-substituted aryl ring scaffold and incorporating thioether sulfurs in each tripod arm also showed extraction selectivity for silver(i); extraction efficiencies towards this metal ion fall in the order L3 > L1 > L2. Physical data are in accord with L1 forming a capsule-like complex of type [Ag3L12]3+ in which silver ions link pairs of pyridyl groups from different ligands. In contrast, L2 yields a complex of type [Ag2L2(NO...
Ion Exchange and Solvent Extraction Series, 2013
Solvent extraction provides the basis for important separation and concentration processes that a... more Solvent extraction provides the basis for important separation and concentration processes that are widely used in hydrometallurgy, waste treatment, e ffluent purification, and material preparation 1– 3 . In a typical extraction process, the complexing agent, the extractant, plays a key role and is responsible for the phase transfer of one or more species of interest between the particular liquid– liquid phases employed. At present, four categories of metal extractants are used in industry: acidic and chelating cation exchanging reagents as well as solvating and anion exchanging reagents. An aim of this review is to show how supramolecular concepts may play a role in influencing extraction processes with the focus placed on the more recent work. Since both calixarene-derived extractants and metal salt extractants are treated in other chapters of this book, these areas have been given less emphasis in the discussion that follows
Chem. Sci., 2014
The transmembrane transport of anions by small synthetic molecules is a growing field in supramol... more The transmembrane transport of anions by small synthetic molecules is a growing field in supramolecular chemistry and has focussed mainly on the transmembrane transport of chloride. On the other hand, the transport of the highly hydrophilic sulfate anion across lipid bilayers is much less developed, even though the inability to transport sulfate across cellular membranes has been linked to a variety of genetic diseases. Tris-thioureas possess high sulfate affinities and have been shown to be excellent chloride and bicarbonate transporters. Herein we report the sulfate transport abilities of a series of tris-ureas and tristhioureas based on a tris(2-aminoethyl)amine or cyclopeptide scaffold. We have developed a new technique based on 33 S NMR that can be used to monitor sulfate transport, using 33 S-labelled sulfate and paramagnetic agents such as Mn 2+ and Fe 3+ to discriminate between intra-and extravesicular sulfate. Reasonable sulfate transport abilities were found for the reported tris-ureas and tris-thioureas, providing a starting point for the development of more powerful synthetic sulfate transporters that can be used in the treatment of certain channelopathies or as a model for biological sulfate transporters.
Chemical Science, 2013
The transport of anions across biological membranes by small molecules is a growing research fiel... more The transport of anions across biological membranes by small molecules is a growing research field due to the potential therapeutic benefits of these compounds. However, little is known about the exact mechanism by which these drug-like molecules work and which molecular features make a good transporter. An extended series of 1-hexyl-3-phenylthioureas were synthesized, fully characterized (NMR, mass spectrometry, IR and single crystal diffraction) and their anion binding and anion transport properties were assessed using 1 H NMR titration techniques and a variety of vesicle-based experiments. Quantitative structure-activity relationship (QSAR) analysis revealed that the anion binding abilities of the mono-thioureas are dominated by the (hydrogen bond) acidity of the thiourea NH function. Furthermore, mathematical models show that the experimental transmembrane anion transport ability is mainly dependent on the lipophilicity of the transporter (partitioning into the membrane), but smaller contributions of molecular size (diffusion) and hydrogen bond acidity (anion binding) were also present. Finally, we provide the first step towards predictable anion transport by employing the QSAR equations to estimate the transmembrane transport ability of four new compounds.
New Journal of Chemistry, 2008
... Marco Wenzelab, Kerstin Gloea, Karsten Gloe*a, Gert Bernhardb, Jack K. Cleggc, Xue-Kui Jic an... more ... Marco Wenzelab, Kerstin Gloea, Karsten Gloe*a, Gert Bernhardb, Jack K. Cleggc, Xue-Kui Jic and Leonard F. Lindoy*c. a Department ... 10, (a) K.-S. Jeong, K.-M. Hahn and YL Cho, Tetrahedron Lett., 1998, 39, 3779 Article ChemPort ; (b) A. Arduini, G. Giorgi, A. Pochini, A. Secchi ...
Journal of the American Chemical Society, 2011
The Journal of Organic Chemistry, 2013
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2011
... bis-b-diketones Jack K. Clegg Bianca Antonioli David J. Bray Karsten Gloe Kerstin Glo... more ... bis-b-diketones Jack K. Clegg Bianca Antonioli David J. Bray Karsten Gloe Kerstin Gloe Katrina A. Jolliffe Olga N. Kataeva George V. Meehan Marco Wenzel Received: 9 March 2011 / Accepted: 21 March 2011 Ó Springer Science+Business Media BV 2011 ...
Inorganic Chemistry, 2008
Two new mixed aza-thia crowns 5-aza-2,8-dithia[9]-(2,9)-1,10-phenanthrolinophane (L 4) and 2,8-di... more Two new mixed aza-thia crowns 5-aza-2,8-dithia[9]-(2,9)-1,10-phenanthrolinophane (L 4) and 2,8-diaza-5-thia[9]-(2,9)-1,10-phenanthrolinophane (L 7) have been synthesized and characterized. The coordination behavior of L 4 and L 7 toward the metal ions Cu II , Zn II , Pb II , Cd II , Hg II , and Ag I was studied in aqueous solution by potentiometric methods, in CD 3 CN/D 2 O 4:1 (v/v) by 1 H NMR titrations and in the solid state. The data obtained were compared with those available for the coordination behavior toward the same metal ions of structurally analogous mixed donor macrocyclic ligands L 1-L 3 , L 5 , L 6 : all these contain a phenanthroline subunit but have only S/O/N(aromatic) donor groups in the remaining portion of the ring and are, therefore, less water-soluble than L 4 and L 7. The complexes [Cd(NO 3) 2 (L 5)], [Pb(L 7)](ClO 4) 2 • 1 / 2 MeCN, [Pb(L 4)](ClO 4) 2 • MeCN, and [Cu(L 7)](ClO 4) 2 • 3 / 2 MeNO 2 were characterized by X-ray crystallography. The efficacy of L 1-L 7 in competitive liquid-liquid metal ion extraction of Cu II , Zn II , Cd II , Pb II , Ag I , and Hg II was assessed. In the absence of Hg II , a clear extraction selectivity for Ag I was observed in all systems investigated.
Dalton Transactions, 2008
Uncharged complexes, formulated as trimeric metallocycles of type [M 3 (L 1) 3 (Py) 6 ] (where M ... more Uncharged complexes, formulated as trimeric metallocycles of type [M 3 (L 1) 3 (Py) 6 ] (where M = cobalt(II), nickel(II) and zinc(II) and L 1 is the doubly deprotonated form of a 1,4-phenylene linked bis-b-diketone ligand of type 1,4-bis(RC(O)CH 2 C(O))C 6 H 4 (R = t-Bu)) have been synthesised, adding to related, previously reported complexes of these metals with L 1 (R = Ph) and copper(II) with L 1 (R = Me, Et, Pr, t-Bu, Ph). New lipophilic ligand derivatives with R = hexyl, octyl or nonyl were also prepared for use in solvent extraction experiments. The X-ray structures of H 2 L 1 (R = t-Bu) and of its trinuclear (triangular) nickel(II) complex [Ni 3 (L 1) 3 (Py) 6 ]•3.5Py (R = t-Bu) are also presented. Electrochemical studies of H 2 L 1 , [Co 3 (L 1) 3 (Py) 6 ], [Ni 3 (L 1) 3 (Py) 6 ], [Cu 3 (L 1) 3 ], [Zn 3 (L 1) 3 (Py) 6 ] and [Fe 4 (L 1) 6 ] (all with R = t-Bu) show that oxidative processes for the complexes are predominantly irreversible, but several examples of quasireversible behaviour also occur and support the assignment of an anodic process, seen between +1.0 and +1.6 V, as involving metal-centred oxidations. The reduction behaviour for the respective metal complexes is not simple, being irreversible in most cases. Solvent extraction studies (water/chloroform) involving the systematic variation of the metal, bis-b-diketone and heterocyclic base concentrations have been performed for cobalt(II) and zinc(II) using a radiotracer technique in order to probe the stoichiometries of the respective extracted species. Significant extraction synergism was observed when 4-ethylpyridine was also present with the bis-b-diketone ligand in the chloroform phase. Competitive extraction studies demonstrated a clear uptake preference for copper(II) over cobalt(II), nickel(II), zinc(II) and cadmium(II).
Dalton Transactions, 2008
Synthesis of 1,3,5-tris(3-methyl-2,4-pentanedione)benzene (2) 2,4-Pentanedione (4.0 g, 40 mmol) w... more Synthesis of 1,3,5-tris(3-methyl-2,4-pentanedione)benzene (2) 2,4-Pentanedione (4.0 g, 40 mmol) was added to a refluxing solution of potassium tert-butoxide (3.4 g, 30 mmol) in tert-butanol (500 mL). 1,3,5-Tris(bromomethyl)benzene 1 (4.0 g, 11 mmol) was then added in small portions along with a catalytic amount of potassium iodide. The reaction mixture was heated at the reflux for 20 h, the solvent was removed under reduced pressure and the residue was extracted with dichloromethane (2 x 125 mL). The organic phase was washed with water (3 x 200 mL) then dried over anhydrous Na 2 SO 4. The dichloromethane was removed under vacuum to yield a pale yellow oil which was purified by preparative tlc (2% MeOH in DCM). (3.8 g, 82 %). Found HRMS-ESI (M + Na) + , m/z =
Chemistry – A European Journal, 2021
Abstract The reaction of UO2(OAc)2 ⋅ 2H2O with the biologically inspired ligand 2‐salicylidene gl... more Abstract The reaction of UO2(OAc)2 ⋅ 2H2O with the biologically inspired ligand 2‐salicylidene glucosamine (H2 L1) results in the formation of the anionic trinuclear uranyl complex [(UO2)3(μ3‐O)(L1)3]2− (1 2−), which was isolated in good yield as its Cs‐salt, [Cs]2 1. Recrystallization of [Cs]2 1 in the presence of 18‐crown‐6 led to formation of a neutral ion pair of type [M(18‐crown‐6)]2 1, which was also obtained for the alkali metal ions Rb+ and K+ (M=Cs, Rb, K). The related ligand, 2‐(2‐hydroxy‐1‐naphthylidene) glucosamine (H2 L2) in a similar procedure with Cs+ gave the corresponding complex [Cs(18‐crown‐6)]2[(UO2)3(μ3‐O)(L2)3 ([Cs(18‐crown‐6)]2 2). From X‐ray investigations, the [(UO2)3O(Ln)3]2− anion (n=1, 2) in each complex is a discrete trinuclear uranyl species that coordinates to the alkali metal ion via three uranyl oxygen atoms. The coordination behavior of H2 L1 and H2 L2 towards UO2 2+ was investigated by NMR, UV/Vis spectroscopy and mass spectrometry, revealing the in situ formation of the 1 2− and 2 2−dianions in solution.
ACS Omega, 2021
Developing biosorbents derived from agro-industrial biomass is considered as an economic and sust... more Developing biosorbents derived from agro-industrial biomass is considered as an economic and sustainable method for dealing with uraniumcontaminated wastewater. The present study explores the feasibility of oxidizing a representative protein-rich biomass, brewer's spent grain (BSG), to an effective and reusable uranyl ion adsorbent to reduce the cost and waste generation during water treatment. The unique composition of BSG favors the oxidation process and yields in a high carboxyl group content (1.3 mmol/g) of the biosorbent. This makes BSG a cheap, sustainable, and suitable raw material independent from pretreatment. The oxidized brewer's spent grain (OBSG) presents a high adsorption capacity of U(VI) of 297.3 mg/g (c 0 (U) = 900 mg/L, pH = 4.7) and fast adsorption kinetics (1 h) compared with other biosorbents reported in the literature. Infrared spectra (Fourier transform infrared), 13 C solid-state nuclear magnetic resonance spectra, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis were employed to characterize the biosorbents and reveal the adsorption mechanisms. The desorption and reusability of OBSG were tested for five cycles, resulting in a remaining adsorption of U(VI) of 100.3 mg/g and a desorption ratio of 89%. This study offers a viable and sustainable approach to convert agro-industrial waste into effective and reusable biosorbents for uranium removal from wastewater.
Dalton Transactions, 2021
Single crystal X-ray analyses, solution NMR and EXAFS studies of a series of f-elements metal(iv)... more Single crystal X-ray analyses, solution NMR and EXAFS studies of a series of f-elements metal(iv) complexes of a 4-phosphoryl pyrazolone ligand show essentially the same coordination of the metal ions in solution and in the solid state.
Chemistry Letters, 2021
Recent advances in guanidinium-based receptors are summarized emphasizing the high affinity of th... more Recent advances in guanidinium-based receptors are summarized emphasizing the high affinity of the guanidinium moiety towards certain anions in highly competitive aqueous media. Particularly the in...
Journal of Hazardous Materials, 2021
Spent hydrodesulfurization (HDS) catalysts, containing considerable amount of pollutants and meta... more Spent hydrodesulfurization (HDS) catalysts, containing considerable amount of pollutants and metals including vanadium (V), molybdenum (Mo), aluminum (Al), and nickel (Ni), are considered as hazardous wastes which will result in not only ecosystem damage but also squandering resource. Herein, a process featuring blank roasting-alkaline leaching is proposed to recover spent HDS catalyst. During roasting, low-valence compounds convert to high-valence oxides which can be leached out by NaOH solution. Afterwards, leaching solution is subjected to crystallization to separate metals. The results show that for samples roasted at 650 °C, 97% V, 96% Mo, and 88% Al are leached out at optimal condition; for samples roasted at 1000 °C, selective leaching of 91% V and 96% Mo respectively, are realized, with negligible Al being dissolved. NiO is insoluble in strong alkali leaving in residue. The advantages of this process are that first, the leaching of V, Mo, and Al can be manipulated by controlling roasting conditions, providing flexible process design. Second, leaching solution can be fully recycled. Finally, mild leaching condition and clean separation of V, Mo, and Al is achieved, proving fundamental information for peer researches to facilitate their future research on the development of more efficient and cleaner technologies.
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2017
This micro review covers recent advances in anion recognition, such as selective developments in ... more This micro review covers recent advances in anion recognition, such as selective developments in the receptor design. Applications to which anion receptors can be applied, for example anion extraction and transport, are highlighted.
Minerals Engineering, 2018
In Vietnam, Dzung Quat Refinery disposes about 7300 tonnes of spent fluid catalytic cracking (SFC... more In Vietnam, Dzung Quat Refinery disposes about 7300 tonnes of spent fluid catalytic cracking (SFCC) catalysts per year. The recovery of rare earth metals (La(III), Ce(III),…) contained in SFCC catalysts using acid leaching process has attracted much attention of scientific community. In this study, the effect of alkaline pre-treatment of spent catalysts prior to the acid leaching process on the leaching yield of La(III) was investigated. The results showed that alkaline pre-treatment caused zeolite destruction, which had a positive effect on the leaching of La (III). High leaching yields of La(III), 80% and 86%, were achieved when the SFCC catalysts were pre-treated with NaOH and NH 3 , respectively, before leaching with 2 M HNO 3 solution at 50°C. These results were comparable with the one obtained from the sample that was leached by 7 M HNO 3 at 50°C without the initial alkaline pretreatment. NH 3 pre-treatment significantly enhanced the zeolite destruction in the SFCC catalysts and increased La(III) leaching yield compared to the NaOH pre-treatment. It is likely due to NH 3 interactions with contaminant metals (e.g. Ni, V, and Fe), which were deposited on catalysts during cracking process.
Korean Journal of Chemical Engineering, 2018
Acid leaching and a two-step solvent extraction procedure were developed to produce high purity ... more Acid leaching and a two-step solvent extraction procedure were developed to produce high purity mixture of La and Ce from iron-rich spent FCC catalyst discharged from Dzung Quat refinery (Vietnam). Acid leaching of the spent catalyst with 2 M HNO 3 and a solid-to-liquid ratio of 1/3 at 80 o C in 1 h dissolved almost 90% of La while 12% of Al and 25% of Fe were transferred to the leachate. The extraction of RE metals and main impurities such as Al and Fe by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) was investigated. Experiments showed that it was necessary to remove Fe before extracting RE and the optimum extraction conditions for a high recovery of RE while 0% of Al extraction were pH1, contact time=10 min, and D2EHPA/TBP volume ratio= 4 : 1. At these conditions, the extraction yields of La(III) and Ce(III) were 72% and 89%, respectively. A two-step solvent extraction was developed to achieve a high purity of RE mixture, which included (1) the removal of impurity Fe by 25% (v/v) diisooctyl phosphinic acid (DiOPA) in n-octane for 140 min, (2) the extraction of rare earths by a mixture of di-2-ethylhexyl phosphoric acid (D2EHPA) and tributyl phosphate (TBP) in n-octane for 10 min without the need for adjusting the pH of the leaching solution.
International Symposium on Microelectronics, 2013
Aluminum and silicon nitride ceramics show high potent as substrate materials for thick film- / h... more Aluminum and silicon nitride ceramics show high potent as substrate materials for thick film- / hybrid applications in the field of power electronics and microwave technology. A main advantage of AlN is its very high thermal conductivity. Si3N4 has also a thermal conductivity comparable to AlN but higher thermal shock resistance and fracture toughness. Nevertheless, the use of Si3N4 in power electronic packages or heater applications is not achieved due to the lack of suitable connection technology such as thick film pastes. The main challenge for the respective pastes is the adhesion on the substrate. The low thermal expansion (CTE) of about 2.8 ppm/K of Si3N4 and material interactions with the thick film components must be considered in the paste development. Therefore, new glasses and glass-ceramic composites are required. Reason development was performed towards AgPd based thick film heater pastes for Si3N4. The pastes consists of AgPd in a 1:1 ratio, an inorganic filler and a g...
Australian Journal of Chemistry, 2015
Two tripodal ligands, each derived from 1,1,1-tris(hydroxymethyl)ethane and terminated respective... more Two tripodal ligands, each derived from 1,1,1-tris(hydroxymethyl)ethane and terminated respectively by 4-pyridyl (L1) and 2-pyridyl groups (L2), have been synthesised. Competitive seven-metal extraction studies (H2O/CHCl3) incorporating equal concentrations of cobalt(ii), nickel(ii), copper(ii), zinc(ii), silver(i), cadmium(ii), and lead(ii) in the aqueous phase and L1 or L2 in the organic phase showed selective extraction of silver(i) in each case. A parallel solvent extraction experiment involving a related tripodal tris-pyridyl ligand (L3) based on a 1,3,5-substituted aryl ring scaffold and incorporating thioether sulfurs in each tripod arm also showed extraction selectivity for silver(i); extraction efficiencies towards this metal ion fall in the order L3 > L1 > L2. Physical data are in accord with L1 forming a capsule-like complex of type [Ag3L12]3+ in which silver ions link pairs of pyridyl groups from different ligands. In contrast, L2 yields a complex of type [Ag2L2(NO...
Ion Exchange and Solvent Extraction Series, 2013
Solvent extraction provides the basis for important separation and concentration processes that a... more Solvent extraction provides the basis for important separation and concentration processes that are widely used in hydrometallurgy, waste treatment, e ffluent purification, and material preparation 1– 3 . In a typical extraction process, the complexing agent, the extractant, plays a key role and is responsible for the phase transfer of one or more species of interest between the particular liquid– liquid phases employed. At present, four categories of metal extractants are used in industry: acidic and chelating cation exchanging reagents as well as solvating and anion exchanging reagents. An aim of this review is to show how supramolecular concepts may play a role in influencing extraction processes with the focus placed on the more recent work. Since both calixarene-derived extractants and metal salt extractants are treated in other chapters of this book, these areas have been given less emphasis in the discussion that follows
Chem. Sci., 2014
The transmembrane transport of anions by small synthetic molecules is a growing field in supramol... more The transmembrane transport of anions by small synthetic molecules is a growing field in supramolecular chemistry and has focussed mainly on the transmembrane transport of chloride. On the other hand, the transport of the highly hydrophilic sulfate anion across lipid bilayers is much less developed, even though the inability to transport sulfate across cellular membranes has been linked to a variety of genetic diseases. Tris-thioureas possess high sulfate affinities and have been shown to be excellent chloride and bicarbonate transporters. Herein we report the sulfate transport abilities of a series of tris-ureas and tristhioureas based on a tris(2-aminoethyl)amine or cyclopeptide scaffold. We have developed a new technique based on 33 S NMR that can be used to monitor sulfate transport, using 33 S-labelled sulfate and paramagnetic agents such as Mn 2+ and Fe 3+ to discriminate between intra-and extravesicular sulfate. Reasonable sulfate transport abilities were found for the reported tris-ureas and tris-thioureas, providing a starting point for the development of more powerful synthetic sulfate transporters that can be used in the treatment of certain channelopathies or as a model for biological sulfate transporters.
Chemical Science, 2013
The transport of anions across biological membranes by small molecules is a growing research fiel... more The transport of anions across biological membranes by small molecules is a growing research field due to the potential therapeutic benefits of these compounds. However, little is known about the exact mechanism by which these drug-like molecules work and which molecular features make a good transporter. An extended series of 1-hexyl-3-phenylthioureas were synthesized, fully characterized (NMR, mass spectrometry, IR and single crystal diffraction) and their anion binding and anion transport properties were assessed using 1 H NMR titration techniques and a variety of vesicle-based experiments. Quantitative structure-activity relationship (QSAR) analysis revealed that the anion binding abilities of the mono-thioureas are dominated by the (hydrogen bond) acidity of the thiourea NH function. Furthermore, mathematical models show that the experimental transmembrane anion transport ability is mainly dependent on the lipophilicity of the transporter (partitioning into the membrane), but smaller contributions of molecular size (diffusion) and hydrogen bond acidity (anion binding) were also present. Finally, we provide the first step towards predictable anion transport by employing the QSAR equations to estimate the transmembrane transport ability of four new compounds.
New Journal of Chemistry, 2008
... Marco Wenzelab, Kerstin Gloea, Karsten Gloe*a, Gert Bernhardb, Jack K. Cleggc, Xue-Kui Jic an... more ... Marco Wenzelab, Kerstin Gloea, Karsten Gloe*a, Gert Bernhardb, Jack K. Cleggc, Xue-Kui Jic and Leonard F. Lindoy*c. a Department ... 10, (a) K.-S. Jeong, K.-M. Hahn and YL Cho, Tetrahedron Lett., 1998, 39, 3779 Article ChemPort ; (b) A. Arduini, G. Giorgi, A. Pochini, A. Secchi ...
Journal of the American Chemical Society, 2011
The Journal of Organic Chemistry, 2013
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2011
... bis-b-diketones Jack K. Clegg Bianca Antonioli David J. Bray Karsten Gloe Kerstin Glo... more ... bis-b-diketones Jack K. Clegg Bianca Antonioli David J. Bray Karsten Gloe Kerstin Gloe Katrina A. Jolliffe Olga N. Kataeva George V. Meehan Marco Wenzel Received: 9 March 2011 / Accepted: 21 March 2011 Ó Springer Science+Business Media BV 2011 ...
Inorganic Chemistry, 2008
Two new mixed aza-thia crowns 5-aza-2,8-dithia[9]-(2,9)-1,10-phenanthrolinophane (L 4) and 2,8-di... more Two new mixed aza-thia crowns 5-aza-2,8-dithia[9]-(2,9)-1,10-phenanthrolinophane (L 4) and 2,8-diaza-5-thia[9]-(2,9)-1,10-phenanthrolinophane (L 7) have been synthesized and characterized. The coordination behavior of L 4 and L 7 toward the metal ions Cu II , Zn II , Pb II , Cd II , Hg II , and Ag I was studied in aqueous solution by potentiometric methods, in CD 3 CN/D 2 O 4:1 (v/v) by 1 H NMR titrations and in the solid state. The data obtained were compared with those available for the coordination behavior toward the same metal ions of structurally analogous mixed donor macrocyclic ligands L 1-L 3 , L 5 , L 6 : all these contain a phenanthroline subunit but have only S/O/N(aromatic) donor groups in the remaining portion of the ring and are, therefore, less water-soluble than L 4 and L 7. The complexes [Cd(NO 3) 2 (L 5)], [Pb(L 7)](ClO 4) 2 • 1 / 2 MeCN, [Pb(L 4)](ClO 4) 2 • MeCN, and [Cu(L 7)](ClO 4) 2 • 3 / 2 MeNO 2 were characterized by X-ray crystallography. The efficacy of L 1-L 7 in competitive liquid-liquid metal ion extraction of Cu II , Zn II , Cd II , Pb II , Ag I , and Hg II was assessed. In the absence of Hg II , a clear extraction selectivity for Ag I was observed in all systems investigated.
Dalton Transactions, 2008
Uncharged complexes, formulated as trimeric metallocycles of type [M 3 (L 1) 3 (Py) 6 ] (where M ... more Uncharged complexes, formulated as trimeric metallocycles of type [M 3 (L 1) 3 (Py) 6 ] (where M = cobalt(II), nickel(II) and zinc(II) and L 1 is the doubly deprotonated form of a 1,4-phenylene linked bis-b-diketone ligand of type 1,4-bis(RC(O)CH 2 C(O))C 6 H 4 (R = t-Bu)) have been synthesised, adding to related, previously reported complexes of these metals with L 1 (R = Ph) and copper(II) with L 1 (R = Me, Et, Pr, t-Bu, Ph). New lipophilic ligand derivatives with R = hexyl, octyl or nonyl were also prepared for use in solvent extraction experiments. The X-ray structures of H 2 L 1 (R = t-Bu) and of its trinuclear (triangular) nickel(II) complex [Ni 3 (L 1) 3 (Py) 6 ]•3.5Py (R = t-Bu) are also presented. Electrochemical studies of H 2 L 1 , [Co 3 (L 1) 3 (Py) 6 ], [Ni 3 (L 1) 3 (Py) 6 ], [Cu 3 (L 1) 3 ], [Zn 3 (L 1) 3 (Py) 6 ] and [Fe 4 (L 1) 6 ] (all with R = t-Bu) show that oxidative processes for the complexes are predominantly irreversible, but several examples of quasireversible behaviour also occur and support the assignment of an anodic process, seen between +1.0 and +1.6 V, as involving metal-centred oxidations. The reduction behaviour for the respective metal complexes is not simple, being irreversible in most cases. Solvent extraction studies (water/chloroform) involving the systematic variation of the metal, bis-b-diketone and heterocyclic base concentrations have been performed for cobalt(II) and zinc(II) using a radiotracer technique in order to probe the stoichiometries of the respective extracted species. Significant extraction synergism was observed when 4-ethylpyridine was also present with the bis-b-diketone ligand in the chloroform phase. Competitive extraction studies demonstrated a clear uptake preference for copper(II) over cobalt(II), nickel(II), zinc(II) and cadmium(II).
Dalton Transactions, 2008
Synthesis of 1,3,5-tris(3-methyl-2,4-pentanedione)benzene (2) 2,4-Pentanedione (4.0 g, 40 mmol) w... more Synthesis of 1,3,5-tris(3-methyl-2,4-pentanedione)benzene (2) 2,4-Pentanedione (4.0 g, 40 mmol) was added to a refluxing solution of potassium tert-butoxide (3.4 g, 30 mmol) in tert-butanol (500 mL). 1,3,5-Tris(bromomethyl)benzene 1 (4.0 g, 11 mmol) was then added in small portions along with a catalytic amount of potassium iodide. The reaction mixture was heated at the reflux for 20 h, the solvent was removed under reduced pressure and the residue was extracted with dichloromethane (2 x 125 mL). The organic phase was washed with water (3 x 200 mL) then dried over anhydrous Na 2 SO 4. The dichloromethane was removed under vacuum to yield a pale yellow oil which was purified by preparative tlc (2% MeOH in DCM). (3.8 g, 82 %). Found HRMS-ESI (M + Na) + , m/z =