Incorporation of strontium and europium in crystals of a-calcium isosaccharinate

The final repository for short-lived, low and intermediate level radioactive waste in Sweden is built to act as a passive repository. Already within a few years after closure water will penetrate the repository and conditions of high alkalinity (pH 10.5-13.5) and low temperature (< 7 degrees C) will prevail. The mobility of radionuclides in the repository is dependent on the radionuclides distribution between solid and liquid phases. In the present work the incorporation of strontium (II) and europium (III) in alpha-calcium isosaccharinate (ISA) under alkaline conditions (pH similar to 10) at 5 degrees C and 50 degrees C have been studied. The results show that strontium and europium are incorporated into alpha-Ca(ISA)(2) when crystallized both at 5 degrees C and 50 degrees C. Europium is incorporated to a greater extent than strontium. The highest incorporation of europium and strontium at 5 degrees C rendered the phase compositions Ca0.986Eu0.014(ISA)(2) (2.4% of Eu(ISA)(3) by mass) and Ca0.98Sr0.02(ISA)(2) (2.2% of Sr(ISA)(2) by mass). XPS spectra show that both trivalent and divalent Eu coexist in the Eu incorporated samples. Strontium ions were found to retard the elongated growth of the Ca(ISA)(2) crystals. The incorporation of Sr2+ and Eu3+ into the solid phase of Ca(ISA)(2) is expected to contribute to a decreased mobility of these ions in the repository

Diastereomeric control of enantioselectivity: evidence for metal cluster catalysis

Enantioselective hydrogenation of tiglic acid effected by diastereomers of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P–P*)] (P–P* = chiral Walphos diphosphine ligand) strongly supports catalysis by intact Ru3 clusters. A catalytic mechanism involving Ru3 clusters has been established by DFT calculations.peerReviewe

Green Synthesis of Metal-Organic Framework Bacterial Cellulose Nanocomposites for Separation Applications

Metal organic frameworks (MOFs) are porous crystalline materials that can be designed to act as selective adsorbents. Due to their high porosity they can possess very high adsorption capacities. However, overcoming the brittleness of these crystalline materials is a challenge for many industrial applications. In order to make use of MOFs for large-scale liquid phase separation processes they can be immobilized on solid supports. For this purpose, nanocellulose can be considered as a promising supporting material due to its high flexibility and biocompatibility. In this study a novel flexible nanocellulose MOF composite material was synthesised in aqueous media by a novel and straightforward in situ one-pot green method. The material consisted of MOF particles of the type MIL-100(Fe) (from Material Institute de Lavoisier, containing Fe(III) 1,3,5-benzenetricarboxylate) immobilized onto bacterial cellulose (BC) nanofibers. The novel nanocomposite material was applied to efficiently separate arsenic and Rhodamine B from aqueous solution, achieving adsorption capacities of 4.81, and 2.77 mg g‒1, respectively. The adsorption process could be well modelled by the nonlinear pseudo-second-order fitting

Synthesis, Characterization and Catalytic Activity Studies of Rhenium Carbonyl Complexes Containing Chiral Diphosphines of the Josiphos and Walphos Families

Ten rhenium carbonyl complexes\u2014[Re(H)(CO)3(1a)], [Re3(mu-H)3(CO)10(1a)], [Re2(CO)9(2a)], [Re2(CO)8(2a)], [Re2(CO)9(2b)], [{Re2(CO)9}2(2b)][Re2(CO)8(2b)], [Re2(CO)8(1b)], [Re2(mu-H)2(CO)6(2b)] and [Re3(mu-H)3(CO)11(2b)] containing different bidentate chiral phosphine ligands of theJosiphos (1a,1b) and Walphos(2a,2b) families have been synthesized and fully characterized (1a:(R)-1-{(SP)-2-[Bis[3,5-bis(trifluoromethylphenylphosphino]ferrocenyl} ethyldi(3,5-xylyl)phosphine,1b:(R)-1-{(SP)-2-[Di(2-furyl)phosphino]ferrocenyl}ethyldi-tert-butylphosphine,2a:(R)-1{(RP)-2-[2-[Bis(4-methoxy-3,5-dimethylphenyl)phosphino]phenyl]ferrocenyl}ethylbis[3,5-bis(trifluoromethyl)phenyl]phosphine and2b:(R)-1-{(RP)-2-[2- (Diphenylphosphino)phenyl]ferrocenyl}ethyldicyclohexylphosphine). The phos-phine-substituted clusters were tested for hydrogenation of tiglic acid [ trans-2-methyl-2-butenoic acid]. The catalytic reactions gave reasonable conversion rates(15\u201388 %) under relatively mild conditions but relatively moderate enantiomeric excesses (8\u201357 %) were observed. The crystal structures of [ReH(CO)3(1a)], [Re2(CO)9(2a)], [{Re2(CO)9}2(2b)] and [Re2(mu-H)(CO)6(2b)] are presented

[μ-Bis(diphenyl­phosphan­yl-κP)methane]­deca­carbonyl­tri-μ-hydrido-trirhenium(I)(3 Re—Re) dichloromethane solvate

In the title compound, [Re3(μ-H)3(C25H22P2)(CO)10]·CH2Cl2, the three Re atoms form a triangle bearing ten terminal carbonyl groups and three edge-bridging hydrides. The bis­(diphenyl­phosphan­yl)methane ligand bridges two Re atoms. Neglecting the Re—Re inter­actions, each Re atom is in a slightly distorted octa­hedral coordination environment. The dichloro­methane solvent mol­ecule is disordered over two sets of sites with fixed occupancies of 0.6 and 0.4

Magnetic metal-organic frameworks for efficient removal of cadmium(II), and lead(II) from aqueous solution

Efficient and convenient methods for the removal of toxic heavy metal ions especially Cd(II) and Pb(II) from aqueous solutions is of great importance due to their serious threat to public health and the ecological system. In this study, two magnetic metal-organic frameworks (namely: Fe3O4@ZIF-8, and Fe3O4@UiO-66-NH2) were synthesized, fully characterized, and applied for the adsorption of Cd(II) and Pb(II) from aqueous solutions. The adsorption efficiencies for the prepared nanocomposites are strongly dependent on the pH of the aqueous solution. The maximum adsorption capacities of Fe3O4@UiO-66-NH2, and Fe3O4@ZIF-8 at pH 6.0 were calculated to be 714.3 mg.g(-), and 370 mg.g(-1) for Cd(II), respectively, and 833.3 mg.g(-1), and 666.7 mg.g(-1) for Pb(II), respectively. The adsorption process follows a pseudo-second-order model and fit the Langmuir isotherm model. Moreover, the thermodynamic studies revealed that the adsorption process is endothermic, and spontaneous in nature. A plausible adsorption mechanism was discussed in detail. The magnetic adsorbents: Fe3O4@ZIF-8, and Fe3O4@UiO-66-NH2 showed excellent reusability, maintaining the same efficiency for at least four consecutive cycles. These results reveal the potential use of magnetic Fe3O4@ZIF-8, and Fe3O4@UiO-66-NH2 as efficient adsorbents in removing Cd(II) and Pb(II) from aqueous solutions

Asymmetric hydrogenation of an α-unsaturated carboxylic acid catalyzed by intact chiral transition metal carbonyl cluster : diastereomeric control of enantioselectivity

Twenty clusters of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P–P*)] (P–P* = chiral diphosphine of the ferrocene-based Walphos or Josiphos families) have been synthesised and characterised. The clusters have been tested as catalysts for asymmetric hydrogenation of tiglic acid [trans-2-methyl-2-butenoic acid]. The observed enantioselectivities and conversion rates strongly support catalysis by intact Ru3 clusters. A catalytic mechanism involving an active Ru3 catalyst generated by CO loss from [(μ-H)2Ru3(μ3-S)(CO)7(μ-P–P*)] has been investigated by DFT calculations.peerReviewe

Rare Earth Ions Adsorption onto Graphene Oxide Nanosheets

<p>Graphene oxide (GO) was synthesized and used as a coagulant of rare earth elements (REEs) from aqueous solution. Stability and adsorption capacities were exhibited for target REEs such as La(III), Nd(III), Gd(III), and Y(III). The parameters influencing the adsorption capacity of the target species including contact time, pH, initial concentration, and temperature were optimized. The adsorption kinetics and thermodynamics were studied. The method showed quantitative recovery (99%) upon desorption using HNO₃ acid (0.1 M) after a short contact time (15 min).</p