Carlos Jorge da Cunha

Bio: Carlos Jorge da Cunha is an academic researcher from Federal University of Paraná. The author has contributed to research in topics: Crystal structure & Ruthenium. The author has an hindex of 10, co-authored 19 publications receiving 405 citations.

Mineral phases of green liquor dregs, slaker grits, lime mud and wood ash of a Kraft pulp and paper mill

Abstract: Four residues generated in a Kraft, pulp and paper plant, were characterized by X-ray fluorescence spectroscopy (XFA), powder X-ray diffraction (XRD), thermogravimmetric analysis (TG) and Fourier transform infrared spectroscopy (FTIR). A quantitative phase composition model, that accounts for the observed data and for the physico-chemical conditions of formation, was postulated for each material. Emphasis was given on the identification of the mineral components of each material. The green liquor dregs and the lime mud contain Calcite and Gipsite. The slaker grits contains Calcite, Portlandite, Pirssonite, Larnite and Brucite. The Calcite phase, present in the dregs and in the lime mud, has small amounts of magnesium replacing calcium. The wood ash contains Quartz as the major crystalline mineral phase.

Nitric oxide photorelease from ruthenium salen complexes in aqueous and organic solutions.

Abstract: The complexes [Ru(salen)(NO)Cl] and [Ru(salen)(NO)(H(2)O)](+) were shown to release the nitrosyl ligand as nitric oxide upon exposure to visible light in organic and aqueous solutions respectively, by means of UV-visible, EPR, and FTIR spectroscopies. The former was prepared by a new synthetic route and had its structure determined by single-crystal X-ray diffraction. A crystal of the dichloromethane solvate is orthorhombic, space group Fdd2 (No. 43) and formula C(16)H(14)ClN(3)O(3)Ru.CH(2)Cl(2), with Z = 16 and cell parameters a = 25.489(4), b = 33.435(4), and c = 9.3716(9) A. The electronic absorption spectra of the complexes were calculated using the INDO/S method. The water-soluble complex is a potential drug for antitumoral phototreatment.

Mineral phases of weathered and recent electric arc furnace dust.

Abstract: A weathered and a recent sample of electric arc furnace dust (EAFD), generated in a southern Brazilian steel industry, were characterized by X-ray fluorescence spectroscopy (XFA), powder X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) probe and Fourier transform infrared spectroscopy (FTIR). A quantitative phase composition model, that accounts for the observed data and for the physico-chemical conditions of formation, was postulated for each material. One sample, in the form of a wet paste, was collected from the lowest part of a landfill and corresponds to a weathered material whereas the other sample was collected from the top portion of the landfill and corresponds to a recently produced material. The dominant cations present in both samples are iron, zinc and lead with minor amounts of manganese, calcium and silicon. The dominant mineralogical phases identified in both materials are Magnetite, Franklinite and Zincite. The recent sample has Laurionite whereas the weathered sample has Hydrocerussite and Hydrozincite.

Bis(2,2‘-bipyridine)(1,2-diimino-9,10-anthraquinone)ruthenium(II) Derivatives: A ZINDO Analysis of a Redox Series Involving Coupled Proton and Electron Transfers

Abstract: The complex bis(2,2‘-bipyridine)(1,2-diimino-9,10-anthraquinone)ruthenium(II) can be reduced or oxidized in protic or aprotic media generating various species. The first two reduced species in protic medium and the first two reduced species in aprotic medium were studied by electrochemistry, spectroelectrochemistry, and electronic, NMR, EPR, and infrared spectroscopy and identified as containing different redox/protonation states of the anthraquinone ligand. The ZINDO method was employed to assign electronic transitions and predict their energies. The extent of electronic coupling between the metal and ligand centers was deduced from the ZINDO analysis as a function of net oxidation state and proton complement.

Bis(2,2′-bipyridine)(1,2-diimino-9,10-anthraquinone)ruthenium(II): a complex containing an exceptionally strong π-accepting α-α′ diimine ligand I. Synthesis, crystal and electronic structures

Abstract: The compound 1,2-diamino-9,10-anthraquinone (DAAQ) binds to ruthenium bis-(2,2′-bipyridine) forming a complex containing the oxidized 1,2-diimino-9,10-anthraquinone (DIAQ). The complex was crystallized as [Ru(bpy)2DIAQ](1,3-benzenedisulfonate)·6.5H2O. Crystal data: triclinic, space group P1−, a = 10.095(2) A , b = 12.035(2) A , c = 17.652(4) A , α = 97.50(3)°, β = 92.54(3)°, γ = 91.65(3)° , Z = 2 . The metal is bound to the diimine site of the DIAQ ligand. There is an extensive n backbonding interaction between the DIAQ ligand and the metal as inferred from theoretical calculations, electrochemical and spectroscopic data. The DIAQ is the best a accepting neutral α-α′ diimine ligand known to date.

An overview of the organic and inorganic phase composition of biomass

Abstract: An extended overview of the organic and inorganic phase composition of biomass was conducted. Some general considerations and problems related to phase composition of biomass as a solid fuel were discussed initially. Then, reference peer-reviewed data including contents of cellulose, hemicellulose, lignin and bulk extractives of 93 varieties of biomass were used and grouped for their comparison and classification. Additionally, reference peer-reviewed data and own investigations for various minor organic components and minerals, and modes of element occurrence identified in biomass were also applied and organised to describe the biomass systematically. It was found that the phase distinctions among the specified natural and anthropogenic (technogenic) biomass groups, sub-groups and varieties are significant and relate to different biomass sources and origin. The phase composition of biomass is highly variable due to the extremely high variations of structural components and different genetic types (authigenic, detrital and technogenic) of inorganic matter. The technogenic biomass group is quite complicated as a result of incorporation of various non-biomass materials during biomass processing. It was identified that the biomass phase composition is significantly different from that of coal. Correlations and associations among phase and chemical characteristics were studied to find some major trends and important relationships occurring in the natural biomass system. Certain leading associations related to the occurrence, content and origin of elements and phases in biomass were identified and discussed, namely: (1) C H (mainly as authigenic cellulose, hemicellulose, lignin and organic extractives); (2) Si Al Fe Na Ti (mostly as detrital silicates and oxyhydroxides, excluding authigenic opal); (3) Ca Mg Mn (commonly as authigenic oxalates and carbonates); and (4) N K S P Cl (normally as authigenic phosphates, sulphates, chlorides and nitrates). Finally, it was emphasised that these important associations have potential applications and can be used for initial classifications or prediction and indicator purposes connected with future advanced and sustainable processing of biomass to biofuels and chemical feedstock.

An overview of the composition and application of biomass ash. Part 1. Phase-mineral and chemical composition and classification

Abstract: An extended overview of the phase–mineral and chemical composition and classification of biomass ash (BA) was conducted. Some general considerations related to the composition of BA and particularly problems associated with this issue were discussed initially. Then, reference peer-reviewed data including phase–mineral composition and properties of BAs plus own investigations were used to describe and organise the BA system. It was found that BA is a complex inorganic–organic mixture with polycomponent, heterogeneous and variable composition. The phase–mineral composition of BA includes: (1) mostly inorganic matter composed of non-crystalline (amorphous) and crystalline to semi-crystalline (mineral) constituents; (2) subordinately organic matter consisting of char and organic minerals; and (3) some fluid matter comprising moisture and gas and gas–liquid inclusions associated with both inorganic and organic matter. Approximately 229 forming, major, minor or accessory phases or minerals were identified in BA. These species have primary, secondary or tertiary origin in the combustion residue and they are generated from natural (authigenic and detrital) and technogenic phases or minerals originally present in biomass. Common topics related to BA such as: terminology clarification; chemical composition; contents and concentration trends; correlations and associations; formation and behaviour; fusion temperatures; and leaching; were discussed and compared to coal ash. A general characterization of the phase–mineral composition and description of the occurrence and origin for common constituents in BA, namely: (1) silicates; (2) oxides and hydroxides; (3) sulphates (plus sulphides, sulphosalts, sulphites and thiosulphates); (4) phosphates; (5) carbonates (plus bicarbonates); (6) chlorides (plus chlorites and chlorates); (7) nitrates; (8) glass; (9) other inorganic phases; (10) organic phases; and (11) organic minerals; were also conducted and compared to coal ash. Finally, certain major associations related to the occurrence, content and origin of elements and phases were identified in the BA system and they include: (1) Si–Al–Fe–Na–Ti (mostly glass, silicates and oxyhydroxides); (2) Ca–Mg–Mn (commonly carbonates, oxyhydroxides, glass, silicates and some phosphates and sulphates); and (3) K–P–S–Cl (normally phosphates, sulphates, chlorides, glass and some silicates and carbonates). It was found that these systematic associations in BA have a key importance in both fundamental and applied aspects, namely their potential application for classification and indicator purposes connected with innovative and sustainable processing of BA. The potential utilization, technological and environmental advantages and challenges related to BA using the above classification approach are described in Part 2 of the present work.

Waste management from pulp and paper production in the European Union

Abstract: Eleven million tonnes of waste are produced yearly by the European pulp and paper industry, of which 70% originates from the production of deinked recycled paper. Wastes are very diverse in composition and consist of rejects, different types of sludges and ashes in mills having on-site incineration treatment. The production of pulp and paper from virgin pulp generates less waste but the waste has similar properties to waste from the production of deinked pulp, although with less inorganics. Due to legislation and increased taxes, landfills are quickly being eliminated as a final destination for wastes in Europe, and incineration with energy recovery is becoming the main waste recovery method. Other options such as pyrolysis, gasification, land spreading, composting and reuse as building material are being applied, although research is still needed for optimization of the processes. Due to the large volumes of waste generated, the high moisture content of the waste and the changing waste composition as a result of process conditions, recovery methods are usually expensive and their environmental impact is still uncertain. For this reason, it is necessary to continue research on different applications of wastes, while taking into account the environmental and economic factors of these waste treatments.

Modeling of charge-transfer transitions and excited states in d6 transition metal complexes by DFT techniques

Abstract: The state of art of the DFT description of charge-transfer electronic excited states of (mostly) d6 transition metal complexes is presented and discussed. A brief theoretical background places DFT amongst quantum-chemical techniques and discusses the approximations involved. The time-dependent DFT (TD-DFT) treatment of electronic transitions is introduced, with emphasis on the challenges presented by long-range charge separation. Various ways how to characterize excited states in chemically relevant terms are discussed. Several detailed case studies demonstrate how DFT describes charge-transfer excited states of ReI or RuII carbonyl-diimine complexes and interprets their photophysics and photochemistry. This “tutorial” section is followed by an overview of DFT and TD-DFT applications to electronic spectroscopy and excited-state properties of metal carbonyls, strongly emissive organometallics, RuII photosensitizers, luminescent “light-switches” and isonitrile complexes of ReI and RuII. Effects of the computational procedure on the quality of the results and the type of information obtained are emphasized. It follows that the most accurate charge-transfer transition energies and descriptions of excited states of low-valent d6 metal complexes are obtained when using hybrid functionals and calculating the molecule in the actual solvent. A rather delocalized picture of charge-transfer states of these complexes emerges, whereby the electron density is excited from the metal atom and part of its coordination sphere to the electron-accepting ligand.

Non-innocent behaviour in mononuclear and polynuclear complexes: consequences for redox and electronic spectroscopic properties

Abstract: This article reviews recent work in the area of non-innocent behaviour in polynuclear metal complexes Non-innocence, which occurs when metal-based and ligand-based redox orbitals are similar in energy, has been known since the first dithiolene complexes of the Ni triad Our recent work in this field is with complexes of two distinct types: polynuclear complexes of Ru(II) with dioxolene-type bridging ligands; and dinuclear complexes based on tris(pyrazolyl)borato-Mo(V) or -Mo(I) units linked by bis-phenolate or bis-pyridyl bridging ligands Detailed redox and UV/Vis/NIR spectroelectrochemical studies on these complexes have been carried out An important point which emerges is that non-innocent behaviour in dinuclear complexes is an essential prerequisite for strong metal–metal electronic coupling across extended bridging ligands Many of the complexes studied show intense charge-transfer transitions in the near-IR region of the spectrum, and the use of these in prototypical optical devices is briefly discussed