Yildiray Topcu

Pyrolysis kinetics of hazelnut husk using thermogravimetric analysis

This study aims at investigating physicochemical properties and pyrolysis kinetics of hazelnut husk, an abundant agricultural waste in Turkey. The physicochemical properties were determined by bomb calorimeter, elemental analysis and FT-IR spectroscopy. Physicochemical analysis results showed that hazelnut husk has a high calorimetric value and high volatile matter content. Pyrolysis experiments were carried out in a thermogravimetric analyzer under inert conditions and operated at different heating rates (5, 10, 20°C/min). Three different kinetic models, the iso-conversional Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) models and Coats-Redfern method were applied on TGA data of hazelnut husk to calculate the kinetic parameters including activation energy, pre-exponential factor and reaction order. Simulation of hazelnut husk pyrolysis using data obtained from TGA analysis showed good agreement with experimental data. Combining with physicochemical properties, it was concluded that this biomass can become useful source of energy or chemicals.

Saccharin complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) with ethanolamine and diethanolamine: synthesis, spectroscopic and thermal characteristics. Crystal structures of [Zn(ea)2(sac)2] and [Cu2(μ-dea)2(sac)2]

Abstract New mixed ligand Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) complexes of saccharin (sac) with ethanolamine (ea) and diethanolamine (dea) were synthesized and characterized by elemental analyses, magnetic moments, UV–Vis and IR spectra. The Co(II)–ea, Co(II)–dea and Cu(II)–dea complexes are dimeric, while all the other complexes of ea and dea are mononuclear. The crystal structures of [Zn(ea)2(sac)2] and [Cu2(μ-dea)2(sac)2] complexes were determined by single crystal X-ray diffraction. In the Zn(II) complex, the Zn(II) ion sits on a center of symmetry and is octahedrally coordinated by two bidentate ea (N, O) and two monodentate sac (N) ligands. The centrosymmetric binuclear Cu(II) complex contains two strongly distorted square-planarly coordinated Cu(II) ions bridged by two alkoxo groups of the deprotonated dea. The dea ligand also coordinates to the Cu(II) ions through its nitrogen, while the other ethanolic group does not involve in coordination. The saccharinate anion coordinates to the Cu(II) ion with its nitrogen. Thermal behavior of the complexes was studied using DTA and TG in nitrogen atmosphere. Endothermic degradation of the ea and dea ligands occurs in the first stages of decomposition and the sac anions decompose at higher temperatures to give corresponding metal oxides or metals.

Thermal behaviour and kinetics of alga Polysiphonia elongata biomass during pyrolysis

The pyrolysis characteristics and kinetics of Polysiphonia elongata were investigated using a thermogravimetric analyzer. The main decomposition of samples occurred between 225 °C and 485 °C at heating rates of 5-40 °C/min; owing to release of 78-82% of total volatiles. The heating rate effected pyrolysis characteristics such as maximum devolatilization rate and decomposition temperature. However, total volatile matter yield was not significantly affected by heating rate. The activation energy of pyrolysis reaction was calculated by model free Friedman and Kissenger-Akahira-Sunose methods and mean values were 116.23 kJ/mol and 126.48 kJ/mol, respectively. A variance in the activation energy with the proceeding conversions was observed for the models applied, which shows that the pyrolysis process was composed of multi-step kinetics. The Coats-Redfern method was used to determine pre-exponential factor and reaction order. The obtained parameters were used in simulation of pyrolysis process and results were in a good agreement with experimental data.

Application of artificial neural networks to co-combustion of hazelnut husk–lignite coal blends

The artificial neural network (ANN) theory is applied to thermal data obtained by non-isothermal thermogravimetric analysis (TGA) from room temperature to 1000°C at different heating rates in air to study co-combustion of hazelnut husk (HH)-lignite coal (LC) blends of various composition. The heating rate, blend ratio and temperature were used in the ANN analysis to predict the TG curves of the blends as parameters that affect the thermal behavior during combustion. The ANN model provides a good prediction of the TG curves for co-combustion with a coefficient of determination for the developed model of 0.9995. The agreement between the experimental data and the predicted values substantiated the accuracy of the ANN calculation.

Synthesis, molecular and crystal structure of bis(triethanolamine)manganese(II) saccharinate: a seven-coordinate manganese complex with tri- and tetradentate triethanolamine ligands

Abstract The synthesis, molecular and crystal structure of bis(triethanolamine)Mn(II) saccharinate, [Mn(tea) 2 ](sac) 2 are reported. The configuration of the tea ligands results in an unusual example of coordination number seven for the Mn(II) ion. The two triethanolamine (tea) ligands coordinate to the Mn(II) ion forming a monocapped trigonal prism geometry, in which one of the tea ligands behaves as a tridentate ligand, while the other one acts as a tetradentate donor. The free and coordinated hydroxyl hydrogens of the tea ligands are involved in hydrogen bonding with the amine nitrogen, carbonyl and sulfonyl oxygens of the neighbouring sac ions to form a three-dimensional infinite network. A weak π–π interaction between the phenyl rings of the sac ions also occurs.

Crystal structure and physico-chemical properties of diaquabis(1,10-phenanthroline)manganese(II) disaccharinate monohydrate

Abstract A novel manganese complex, [Mn(phen) 2 (H 2 O) 2 ](sac) 2 ·H 2 O, was synthesized by the reaction of [Mn(sac) 2 (H 2 O) 4 ]·2H 2 O with 1,10-phenantroline in aqueous solution and characterized by elemental analysis, IR spectral evidence, magnetic measurements, thermal analysis and single crystal X-ray diffraction. The compound crystallizes in triclinic system, space group P -1, with Z =2. The saccharinate ions do not coordinate the central metal, instead are present as the complementary anions. In the complex cation, Mn(II) is coordinated by two phen and two aqua ligands, and exhibits a distorted octahedral coordination with a high-spin configuration. The presence of lattice and coordinate water molecules are also confirmed by thermal analysis and IR spectroscopy.

Cyano-complexes and salts with tetracyanonickellateII and N,N-bis(2-hydroxyethyl)-ethylenediamine: synthesis, IR spectra, magnetic properties, thermal analyses, and crystal structures

Four cyano complexes, [Ni(N-bishydeten)Ni(CN)4] n (c1), [Cu(N-bishydeten)2][Ni(CN)4] (c2), [Zn2(N-bishydeten)2Ni(CN)4] n (c3), and [Cd(N-bishydeten)2][Ni(CN)4] (c4), have been synthesized and characterized by FT-IR, elemental, and thermal analyses. The structures of c2 and c4 were determined by single-crystal X-ray diffraction studies; both structures contain isolated cations and anions. The c2 consists of [Cu(N-bishydeten)2]2+ with octahedrally coordinated CuII and diamagnetic [Ni(CN)4]2–, but c4 consists of [Cd(N-bishydeten)2]2+, in which CdII is eight coordinate with two tetradentate N-bishydeten and diamagnetic [Ni(CN)4]2–. The value of the shape measure S (o) indicates that the coordination geometry around CdII lies along D 2d [dodecahedron; (dd)], C 2v [bicapped trigonal prism; (btp)], and D 4d [square antiprism; (sap)] but close to D 2d and D 4d. Variable temperature magnetic susceptibility measurements of c1 and c2 show the presence of little antiferromagnetic interaction below 20 K. Thermal analyses reveal that first neutral N-bishydeten and then cyano ligands were liberated from the complexes.

An eight-coordinate strontium complex with two tetradentate triethanolamine ligands: synthesis, IR spectra, thermal analysis and crystal structure of bis(triethanolamine)strontium(II) saccharinate

Bis(triethanolamine)strontium(II) saccharinate, [Sr(tea) 2 ](sac) 2 was synthesized and characterized by IR spectroscopy, thermal analysis and X-ray diffraction techniques. The compound crystallizes in orthorhombic system and consists of two sac anions and a complex cation, in which each tea ligand behaves as a tetradentate ligand and their configuration results in an eight-coordinate strontium(II) complex with a bicapped trigonal prism geometry. The anions and cations are linked by the intermolecular hydrogen bonds between the hydroxyl hydrogens of the tea ligands and the amine N, and carbonyl O atoms of the neighbouring sac ions, forming one-dimensional chains running parallel to c. The adjacent chains are held together by van der Waals interactions, creating a three-dimensional network. The FTIR spectra and thermal decomposition of the complex were discussed.

Synthesis and Structure of Trans‐bis(ethanolamine)bis(saccharinato)mercury(II)

Trans-bis(ethanolamine)bis(saccharinato)mercury(II), [Hg(ea) 2 (sac) 2 ], where ea and sac denote the ethanolamine molecule and the saccharinate anion, respectively, crystallizes in the triclinic space group P1 (No. 2) with a = 9.4651(5), b = 10.4365 (5), c = 11.9314 (6) A, a = 84.402(1)° β= 78.313(1)°, γ= 75.307(1)°, Z = 2, V= 1115.11(10) A 3 . The structure consists of isolated [Hg(ea) 2 (sac) 2 ] units in which the Hg(II) ion is octahedrally coordinated by two nitrogen and two oxygen atoms of two neutral ea ligands, and two nitrogen atoms of two sac ligands. The ea acts as a bidentate N- and O-donor ligand and occupies the trans positions of the equatorial plane of the coordination octahedron forming a five-membered chelate ring, while sac behaves as a monodentate N-donor ligand occupying the axial positions. The average Hg-N sac and Hg-N ea bond distances are 2.739(3) and 2.114(7) A, respectively. The crystal exhibits extensive hydrogen bonds between the hydroxyl and amine hydrogen atoms of the ea ligands and the sulfonyl, carbonyl and amine groups of the sac ligands.

X-ray crystal structure of trans-bis(monoethanolamine) bis(saccharinato)nickel(II)

The crystal structure of trans-bis(monoethanolamine)bis(saccharinato)nickel(II), [Ni(C7H4NO3S)2(C2H7NO)2], has been determined from X-ray diffraction data. The metal complex is monoclinic, with a = 11.0555(5), b = 8.9103(4), c = 11.3890(5) Å, β = 105.0230(10)°, Z = 2, and space group P21/c. The structure consists of individual molecules. Two monoethanolamine molecules and two saccharinate anions coordinate the nickel atom forming a distorted octahedron. The monoethanolamine molecules act as a bidentate ligand and form five-membered trans chelate rings, which constitute the plane of the coordination octahedron, while two saccharinate ions behave as a monodentate ligand occupying the axial positions. Intermolecular hydrogen bonds link the molecules to form a three-dimensional infinite structure.