Inorganics

13 pages, 2438 KiB

Open AccessArticle

Efficient Separation of Heavy Metals by Magnetic Nanostructured Beads

by Lisandra de Castro Alves, Susana Yáñez-Vilar, Yolanda Piñeiro-Redondo and José Rivas

Inorganics 2020, 8(6), 40; https://doi.org/10.3390/inorganics8060040 - 26 Jun 2020

Cited by 6 | Viewed by 2512

This study reports the ability of magnetic alginate activated carbon (MAAC) beads to remove Cd(II), Hg(II), and Ni(II) from water in a mono-metal and ternary system. The adsorption capacity of the MAAC beads was highest in the mono-metal system. The removal efficiency of such metal ions falls in the range of 20–80% and it followed the order Cd(II) > Ni(II) > Hg(II). The model that best fitted in the ternary system was the Freundlich isotherm, while in the mono-system it was the Langmuir isotherm. The maximum Cd(II), Hg(II), and Ni(II) adsorption capacities calculated from the Freundlich isotherm in the mono-metal system were 7.09, 5.08, and 4.82 (mg/g) (mg/L)^1/n, respectively. Lower adsorption capacity was observed in the ternary system due to the competition of metal ions for available adsorption sites. Desorption and reusability experiments demonstrated the MAAC beads could be used for at least five consecutive adsorption/desorption cycles. These findings suggest the practical use of the MAAC beads as efficient adsorbent for the removal of heavy metals from wastewater. Full article

(This article belongs to the Special Issue Smart Tools for Smart Applications: New Insights into Inorganic Magnetic Systems and Materials)

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43 pages, 10271 KiB

Open AccessReview

Smart Ligands for Efficient 3d-, 4d- and 5d-Metal Single-Molecule Magnets and Single-Ion Magnets

by Panagiota S. Perlepe, Diamantoula Maniaki, Evangelos Pilichos, Eugenia Katsoulakou and Spyros P. Perlepes

Inorganics 2020, 8(6), 39; https://doi.org/10.3390/inorganics8060039 - 29 May 2020

Cited by 27 | Viewed by 4993

Abstract

There has been a renaissance in the interdisciplinary field of Molecular Magnetism since ~2000, due to the discovery of the impressive properties and potential applications of d- and f-metal Single-Molecule Magnets (SMMs) and Single-Ion Magnets (SIMs) or Monometallic Single-Molecule Magnets. One of the consequences of this discovery has been an explosive growth in synthetic molecular inorganic and organometallic chemistry. In SMM and SIM chemistry, inorganic and organic ligands play a decisive role, sometimes equally important to that of the magnetic metal ion(s). In SMM chemistry, bridging ligands that propagate strong ferromagnetic exchange interactions between the metal ions resulting in large spin ground states, well isolated from excited states, are preferable; however, antiferromagnetic coupling can also lead to SMM behavior. In SIM chemistry, ligands that create a strong axial crystal field are highly desirable for metal ions with oblate electron density, e.g., Tb^III and Dy^III, whereas equatorial crystal fields lead to SMM behavior in complexes based on metal ions with prolate electron density, e.g., Er^III. In this review, we have attempted to highlight the use of few, efficient ligands in the chemistry of transition-metal SMMs and SIMs, through selected examples. The content of the review is purely chemical and it is assumed that the reader has a good knowledge of synthetic, structural and physical inorganic chemistry, as well as of the properties of SIMs and SMMs and the techniques of their study. The ligands that will be discussed are the azide ion, the cyanido group, the tris(trimethylsilyl)methanide, the cyclopentanienido group, soft (based on the Hard-Soft Acid-Base model) ligands, metallacrowns combined with click chemistry, deprotonated aliphatic diols, and the family of 2-pyridyl ketoximes, including some of its elaborate derivatives. The rationale behind the selection of the ligands will be emphasized. Full article

(This article belongs to the Special Issue Smart Tools for Smart Applications: New Insights into Inorganic Magnetic Systems and Materials)

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13 pages, 2085 KiB

Open AccessArticle

Susceptibility of the Formate Hydrogenlyase Reaction to the Protonophore CCCP Depends on the Total Hydrogenase Composition

by Janik Telleria Marloth and Constanze Pinske

Inorganics 2020, 8(6), 38; https://doi.org/10.3390/inorganics8060038 - 28 May 2020

Cited by 2 | Viewed by 3207

Abstract

Fermentative hydrogen production by enterobacteria derives from the activity of the formate hydrogenlyase (FHL) complex, which couples formate oxidation to H₂ production. The molybdenum-containing formate dehydrogenase and type-4 [NiFe]-hydrogenase together with three iron-sulfur proteins form the soluble domain, which is attached to the membrane by two integral membrane subunits. The FHL complex is phylogenetically related to respiratory complex I, and it is suspected that it has a role in energy conservation similar to the proton-pumping activity of complex I. We monitored the H₂-producing activity of FHL in the presence of different concentrations of the protonophore CCCP. We found an inhibition with an apparent EC₅₀ of 31 µM CCCP in the presence of glucose, a higher tolerance towards CCCP when only the oxidizing hydrogenase Hyd-1 was present, but a higher sensitivity when only Hyd-2 was present. The presence of 200 mM monovalent cations reduced the FHL activity by more than 20%. The Na⁺/H⁺ antiporter inhibitor 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) combined with CCCP completely inhibited H₂ production. These results indicate a coupling not only between Na⁺ transport activity and H₂ production activity, but also between the FHL reaction, proton import and cation export. Full article

(This article belongs to the Special Issue Transition Metals in Catalysis: The Functional Relationship of Fe–S Clusters and Molybdenum or Tungsten Cofactor-Containing Enzyme Systems)

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Inorganics, Volume 8, Issue 6 (June 2020) – 3 articles

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