J.O. Hill

A kinetic analysis of the pyrolysis of some australian coals by non-isothermal thermogravimetry

The pyrolysis of a suite of brown coal samples and bituminous coal maceral concentrates is investigated by non-isothermal thermogravimetry. The TG data for these coals reveal a two-stage pyrolysis process. The activation energy for the primary pyrolysis stage is considerably higher than that for the secondary pyrolysis stage. It is evident that a particular coal may be characterised by the weighted mean apparent pyrolysis activation energy which correlates with the corresponding specific energy of the coal.ZusammenfassungMittels nichtisothermer Thermogravimetrie wurde die Pyrolyse einer Reihe von Braunkohlenproben und Mazeralkonzentrate aus bituminösen Kohlen untersucht. Die TG-Daten dieser Kohlen weisen einen zweischrittigen Pyrolyseprozeß auf. Die Aktivierungsenergie für den ersten Pyrolyseschritt ist erheblich höher als die des zweiten Pyrolyseschrittes. Es ist offensichtlich, daß eine gegebene Kohle durch den gewichteten Mittelwert der scheinbaren Aktivierungsenergie der Pyrolyse charakterisiert werden kann, welcher mit der entsprechenden spezifischen Energie der Kohle korreliert.

Separation of substituted phenols, including eleven priority pollutants using high-performance liquid chromatography

Abstract High-performance liquid chromatography separation by isocratic elution of a wide range of substituted phenols, including the so-called priority pollutants, is investigated. By careful selection of the eluting solvent mixture, the method may be adapted for the routine analysis of phenols particularly phenolic aqueous environemental samples.

Thermal analysis of copper dithiocarbamates

Abstract Seven copper(II) dithiocarbamate complexes [Cu(R 2 Dtc) 2 : R 2 = Me 2 , Et 2 , nPr 2 , nBu 2 , cycHex 2 , Et Ph, pyrrol and pip] have been prepared and examined by thermogravimetric analysis (TG). All the complexes show similar TG profiles whether heated in an atmosphere of air or nitrogen. Complete TG, DTA data are reported for copper diethyldithiocarbamate (air, nitrogen and vacuum atmospheres). Copper diethyldithiocarbamate is completely volatile (190–260°C) under vacuum (0.8τ), but in air and nitrogen only partial volatility is exhibited; thermal decomposition begins at 220°C and a residue of cuprous sulphide results at 350°C.

The Analytical Chemistry of Metal Dithiocarbamate Complexes

CONTENTS Page INTRODUCTION 6 1. ELECTROANALYTICAL TECHNIQUES 7 Polarographie Methods 8 Amperometric Titrations 13 Potentiometrie Titrations 16 Other Electroanalytical Techniques 18 2. SEPARATORY TECHNIQUES 19 High Performance Liquid Chromatography (HPLC) 19 Gas Chromatography (GC) 21 Thin Layer Chromatography (TLC) 24 Solvent Extraction 25 3. RADIOCHEMICAL TECHNIQUES 2 9 4. THERMOANALYTICAL TECHNIQUES 3 0 Volatility 30 Thermal Decomposition 31 5. SPECTROSCOPIC TECHNIQUES 35 UVVisible Spectrophotometry 35 Atomic Absorption Spectrometry (AAS) 42 X-Ray Fluorescence Spectrometry (XRF) 44 Other Spectroscopic Techniques 46 6. MASS SPECTROMETRY TECHNIQUES 4 7 7. TITRIMETRIC METHODS 4 9 8. MISCELLANEOUS 54 ACKNOWLEDGEMENTS 5 6 REFERENCES 5 7

A re-evaluation of the enthalpy of sublimation of some metal acetylacetonate complexes

Abstract Sublimation enthalpies for Al(III), Fe(III) and Zn(II) acetylacetonates derived using isoteniscopic, sublimation bulb and spoon gauge techniques are reported. Selected sublimation enthalpies are Al(C 5 H 7 O 2 ) 3 , 118.6 ± 7.8; Fe(C 5 H 7 O 2 , 113.6 ± 3.8; and Zn(C 5 H 7 O 2 ) 2 , 117 ± 3 kJ mole −1 , respectively.

Synthesis and characterisation of some secondary amine-dithiocarbamate salts

Abstract The synthesis of five dialkylammonium dialkyldithiocarbamates, = ethyl , n-propyl, i-propyl, n-butyl, i-butyl) is reported together with corresponding solubility, volatility, conductivity and IR spectral data. The n-propyl, i-propyl and n-butyl compounds are volatile and the IR and conductance data suggest that the bonding between the dialkylammonium and dialkyldithiocarbamate moeities is predominantly ionic.

A thermogravimetry/differential thermal analysis, evolved gas analysis and pyrolysis/gas chromatography—mass spectrometry study of tetrakis (diethyldithiocarbamato)tin(IV)

Abstract The thermal decomposition of tetrakis(diethyldithiocarbamato)tin(IV) has been studied by TG/DTA, EGA and P/GC-MS techniques. From the P/GC-MS analysis, it is apparent that the denticity of the dithiocarbamate ligand influences the mechanism of decomposition. Initially, the monodentate ligands decompose by a radical mechanism to form tetraethylthiuramdisulphide which decomposes further into carbon disulphide and diethylamine. The intermediate formed, bis(diethydithiocarbamato)tin(II), decomposes in two different ways. The bidentate ligands decompose with the liberation of carbon disulphide and tetraethylthiourea, whereas the monodentate ligands, formed as a result of the high temperatures, decompose to produce S-ethyl N,N-diethyldithiocarbamate and ethylisothiocyanate. The overall thermal decomposition mechenism of tetrakis(diethyldithiocarbamato)tin(IV) is complex and the primary decomposition involved both ionic and radical recombination reactions.

A thermogravimetry/differential thermal analysis, evolved gas analysis and pyrolysis/ gas chromatography—mass spectrometry study of dihalotin(IV)bisdiethydithiocarbamates

Abstract Three dihalotin(IV) bisdiethyldithiocarbamates have been subjected to controlled pyrolysis/GC—MS analysis and the major products of the first stage of decomposition identified. These data, in addition to those obtained from TG/DTA analysis are used to determine the decomposition mechanism of the complexes. In an inert atmosphere dihalotin(IV)bisdiethyldithiocarbamate pyrolyses to yield carbon disulphide and tetraethylthiourea as the major volatile products and dihalotinsulphide as the major solid phase intermediate, which subsequently decomposes to yield tin sulphide. It has been conclusively shown that the nature of the halogen ligands has no influence on the mode of thermal decomposition of these complexes. The proposed thermal decomposition mechanism correlates well with the known structure of the complexes.

Thermal studies on nickel alkyl xanthate complexes

Abstract This paper is the first of a series reporting the results of a comprehensive thermogravimetric and calorimetric analysis of netel complexes of various alkyI derivatives of xanthic acid and dithiocarbamic acid. Eleven nickel alkyl xanthates have been prepared and analysed thermogravimetrically. Detailed volatilisation characteristics of these complexes are also reported. The thermal stability of nickel alkyl xanthates is best described as moderate since all decompose initially to NiS at relatively low temperatures (140–180°C). A thermal decomposition mechanism for the nickel alkyl xanthates involving carbonyl sulphide, nickel sulphide and S-ethyl O-ethyl xanthate as stable intermediates has been con- firmed by mass spectrometric techniques. It is apparent from the thermogravimetric analysis data and volatilisation characteristics that the “nature” of the terminal alkyl group attached to the xanthate moiety considerably influences the thermal stability of nickel alkyl xanthates.

Thermal studies on palladium alkyl xanthates

Abstract Eleven palladium(II) alkylxanthates: Pd(ROCSS) 2 [RMe, Et, nPr, iPr, nBu, iBu, tBu, nAm, iAm, nHex and cyclohex], have been prepared and their thermal properties investigated by thermogravimetric analysis. The complexes, although volatile under vacuum (10 −2 mm Hg), decompose without volatilization at normal atmospheric pressure leaving a residue of palladium metal at 950°C. The intermediate decomposition products were identified mass spectrometrically and a thermal decomposition mechanism is proposed.