Application of ESR Spectroscopy in Bleaching Studies

Summary In this study several pulp components were characterized by ESR spectroscopy. Free radicals present in the pulp lignin gave a well-defined signal, and the residual lignin content during a bleaching sequence could be followed using this technique. Organic radicals on the pulp carbohydrates were also detected and could be related to the formation of chromophore structures in pulp. Further, ESR spectroscopy made it possible to characterize several transition metal ions in pulp. Special attention was paid to metal retention and the impact of a sodium borohydride treatment, and the formation and evolution of complexes between metal ions and pulp components was scrutinized.

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Effect of Transitional Metals (Mn and Ni) Substitution in LiCoPO4 Olivines

Molecules ◽

10.3390/molecules25030601 ◽

2020 ◽

Vol 25 (3) ◽

pp. 601

Author(s):

Oriele Palumbo ◽

Jessica Manzi ◽

Daniele Meggiolaro ◽

Francesco M. Vitucci ◽

Francesco Trequattrini ◽

...

Keyword(s):

Transition Metal ◽

Metal Ions ◽

Structural Changes ◽

Transition Metal Ions ◽

Xrd Analysis ◽

Partial Substitution ◽

Structural Alterations ◽

X Ray ◽

Transitional Metals ◽

The Impact

Transition metal substitution is a key strategy to optimize the functional properties of advanced crystalline materials used as positive electrodes in secondary lithium batteries (LIBs). Here we investigate the structural alterations in the olivine lattice of Mn and Ni substituted LiCoPO4 phase and the impact on performance in LIBs. X-ray diffraction (XRD) and extended X-ray absorption experiments have been carried out in order to highlight the structural alterations induced by partial substitution of cobalt by manganese and nickel. XRD analysis suggests that substitution induces an expansion of the lattices and an increase of the antisite disorder between lithium and transition metal ions in the structure. XAS data highlight negligible electronic disorder but a relevant modulation in the local coordination around the different metal ions. Moreover, galvanostatic tests showed poor reversibility of the redox reaction compared to the pure LCP sample, and this failure is discussed in detail in view of the observed remarkable structural changes.

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Sulphur-containing Amino Acids: Protective Role Against Free Radicals and Heavy Metals

Current Medicinal Chemistry ◽

10.2174/0929867324666170609075434 ◽

2018 ◽

Vol 25 (3) ◽

pp. 324-335 ◽

Cited By ~ 20

Author(s):

Mirjana B. Colovic ◽

Vesna M. Vasic ◽

Dragan M. Djuric ◽

Danijela Z. Krstic

Keyword(s):

Heavy Metals ◽

Amino Acids ◽

Free Radicals ◽

Metal Ions ◽

Toxic Metal ◽

Transition Metal Ions ◽

Protective Role ◽

Protective Effects ◽

Beneficial Effects ◽

Antioxidant Agents

Background: Sulphur is an abundant element in biological systems, which plays an important role in processes essential for life as a constituent of proteins, vitamins and other crucial biomolecules. The major source of sulphur for humans is plants being able to use inorganic sulphur in the purpose of sulphur-containing amino acids synthesis. Sulphur-containing amino acids include methionine, cysteine, homocysteine, and taurine. Methionine and cysteine are classified as proteinogenic, canonic amino acids incorporated in protein structure. Sulphur amino acids are involved in the synthesis of intracellular antioxidants such as glutathione and N-acetyl cysteine. Moreover, naturally occurring sulphur-containing ligands are effective and safe detoxifying agents, often used in order to prevent toxic metal ions effects and their accumulation in human body. Methods: Literature search for peer-reviewed articles was performed using PubMed and Scopus databases, and utilizing appropriate keywords. Results: This review is focused on sulphur-containing amino acids – methionine, cysteine, taurine, and their derivatives – glutathione and N-acetylcysteine, and their defense effects as antioxidant agents against free radicals. Additionally, the protective effects of sulphur-containing ligands against the toxic effects of heavy and transition metal ions, and their reactivation role towards the enzyme inhibition are described. Conclusion: Sulphur-containing amino acids represent a powerful part of cell antioxidant system. Thus, they are essential in the maintenance of normal cellular functions and health. In addition to their worthy antioxidant action, sulphur-containing amino acids may offer a chelating site for heavy metals. Accordingly, they may be supplemented during chelating therapy, providing beneficial effects in eliminating toxic metals.

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Effect of Transition Metal Ions Dopants on Photocatalytic Properties of Titanium-Baring Blast Furance Slag

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.113-116.2105 ◽

2010 ◽

Vol 113-116 ◽

pp. 2105-2109 ◽

Cited By ~ 1

Author(s):

He Yang ◽

Li Li Bai ◽

Er Jun Bu ◽

Mi Zhou ◽

Xiang Xin Xue

Keyword(s):

Transition Metal ◽

Metal Ions ◽

Degradation Rate ◽

Transition Metal Ions ◽

Photocatalytic Properties ◽

Spectral Absorption ◽

Doping Amount ◽

Photocatalytic Material ◽

Analytical Tools ◽

The Impact

Transition metal ions have wider optical absorption than TiO2. They can extend the range of absorption light to visible light, taking titanium-baring blast furance slag(TBBFS) as photocatalytic material with a certain amount of transition metal ions to broaden the scope of its spectral absorption and to improve its photocatalytic properties. The impact of transition metal ions Fe3 +, Zr4 + on photocatalytic properties of TBBFS was studied and their optimal doping was searched. TBBFS was grinded and re-doped with transition metal ions and then roasted to prepare photocatalytic materials, using methylene blue’s degradation rate under condition of UV irradiation to evaluate material properties and then using XRD, SEM and other analytical tools for its material characterization. Results show that: doping of transition metals Fe (NO3)3 and ZrO2 can improve the photocatalytic nature of TBBFS and the best doping amount is 0.5% and 3.0% relatively, and its degradation rate is 69.2% and 73.0% respectively.

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