Trevor Melvyn Letcher

Trevor Melvyn Letcher
University of KwaZulu-Natal | ukzn · Department of Chemistry

BSc,BSc(Hons) BEd, MSc, PhD, FRSC,

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287
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Publications

Publications (287)
Book
Waste: A Handbook for Management, Second Edition, provides information on a wide range of hot topics and developing areas, such as hydraulic fracturing, microplastics, waste management in developing countries, and waste-exposure-outcome pathways. Beginning with an overview of the current waste landscape, including green engineering, processing prin...
Chapter
The raison d'etre for the new book on wind energy engineering is discussed with a focus on our changing climate and the buildup of atmospheric carbon dioxide; hence the title of this introductory chapter-Why Wind Energy? The background to wind power is briefly mentioned.The advantages of wind energy are discussed together with a look at the challen...
Article
Full-text available
The applicability of 1-alkyl-imidazoluim-based ionic liquids (ILs) for the extraction of ethanol from hexadecane by solvent extraction was studied by determining the liquid-liquid equilibrium (LLE) data for the ternary systems: {hexadecane (1) + ethanol (2) + 1,3-dimethylimidazolium methyl sulfate, [MMIM][MeSO4] (3) or 1-ethyl-3-methylimidazolium m...
Article
This review covers recent developments in the area of excess molar volumes for mixtures of {ILs (1) + H2O (2)} where ILs refers to ionic liquids involving cations: imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium and ammonium groups; and anions: tetraborate, triflate, hydrogensulphate, methylsulphate, ethylsulphate, thiocyanate, d...
Article
The ternary (liquid + liquid) equilibrium (LLE) data for mixtures of dodecane (C12H26) and ethanol with ionic liquids 1,3-dimethylimidazolium methylsulfate [Mmim][MeSO4], 1-ethyl-3-methylimidazolium methylsulfate, [Emim][MeSO4] and 1-butyl-3-methylimidazolium methylsulfate, [Bmim][MeSO4], were studied at T = 298.15 K and 0.101 MPa. The selectivity...
Book
Earth's climate is always changing. As the debate over the Earth's climate has grown, the term "climate change" has come to refer primarily to changes we've seen over recent years and those that are predicted to be coming, mainly as a result of human behavior. Climate Change: Observed Impacts on Planet Earth, Second Edition, serves as a broad, acce...
Chapter
In this chapter, we look at. •driving forces behind the need to consider new forms of energy,•the looming problem of global warming and climate change,•the options for electricity generation and for transport fuel,•the energy situation today,•the big question: How can we reduce the stranglehold that fossil fuels have on our economy and lives?The en...
Article
Full-text available
The book Future Energy has been produced in order for the reader to make reasonable, logical and correct decisions on our future energy as a result of two of the most serious problems that the civilized world has had to face: the looming shortage of oil (which supplies most of our transport fuel) and the alarming rise in atmospheric carbon dioxide...
Article
The infinite dilution activity coefficients for 25 hydrocarbon solutes in diethylene glycol (DEG) and triethylene glycol (TEG) were measured using the gas–liquid chromatography technique with pre-saturation of the carrier gas. The hydrocarbon solutes included n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes and alkanols. At the temper...
Article
Activity coefficients at infinite dilution for organic solutes, which include n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes, alcohols and ketones, in the ionic liquid trihexyltetradecylphosphonium bis (trifluoromethylsulfonyl) imide were measured by gas-liquid chromatography using the latter as the stationary phase. This ionic liqu...
Article
The infinite dilution activity coefficients for 25 solutes (n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes and alcohols) were measured in N-formylmorpholine (NFM) and N-methylpyrrolidone (NMP). This was performed using the gas–liquid chromatography (glc) technique with pre-saturation of the carrier gas. The solvents that were used h...
Book
Unraveling Environmental Disasters provides scientific explanations of the most threatening current and future environmental disasters, including an analysis of ways that the disaster could have been prevented and how the risk of similar disasters can be minimized in the future. Treats disasters as complex systems. Provides predictions based upon s...
Article
Activity coefficients at infinite dilution for 31 organic solutes (n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes, alcohols, and ketones) in the ionic liquid trihexyltetradecylphosphonium hexafluorophosphate [3C6C14P][PF6] were determined by gas–liquid chromatography at T = (313.15, 333.15, 353.15, and 363.15) K. From experimental v...
Book
Unraveling Environmental Disasters provides scientific explanations of the most threatening current and future environmental disasters, including an analysis of ways that the disaster could have been prevented and how the risk of similar disasters can be minimized in the future. Treats disasters as complex systems. Provides predictions based upon s...
Article
Household hazardous waste (HHW) is a term used to describe hazardous wastes entering the municipal waste stream. It represents a variety of waste types classified together based on the possession of hazardous properties. This chapter takes a look at the problems related to the disposal of chemicals and other hazardous substances used in the home. H...
Chapter
Environmental problems faced today differ from those of most of the Earth's history in both kind and degree. Society and its elected and appointed delegates increasingly respond to waste-related problems by writing and enforcing laws. The number of laws enacted to address various aspects of wastes has grown substantially in recent decades. Waste ma...
Article
The phase diagrams for binary systems of {1-propyl-1-methylpiperidinium bis{(trifluoromethyl)sulfonyl}imide [PMPIP][NTf2] + an alcohol (butan-1-ol, pentan-1-ol hexan-1-ol, heptan-1-ol, octan-1-ol, decan-1-ol and undecan-1-ol} have been determined at atmospheric pressure using a dynamic method. The influence of an alcohol chain length is discussed f...
Article
Activity coefficients at infinite dilution were determined for 27 solutes: n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes, alcohols, and ketones in the ionic liquid 1-butyl-3-methylimidazolium hexafluoroantimonate, [BMIM][SbF6], by gas–liquid chromatography at three different temperatures, T=(313.15, 323.15, and 333.15)K. The result...
Article
New isoquinolinium ionic liquid has been synthesized from N-octylisoquinolinium bromide as a substrate. The specific basic characterization of the new compound by NMR spectra, elementary analysis and water content is presented. The activity coefficients at infinite dilution, for 37 solutes viz. alkanes, alkenes, alkynes, cycloalkanes, aromatic hydr...
Article
Isoquinolinium ionic liquid (IL) has been synthesized from N-hexylisoquinolinium bromide as a substrate. Specific basic characterization of the synthesized compound is included, which includes NMR spectra, elementary analysis, and water content. The basic thermal properties of the pure IL, that is, melting and solid-solid transition temperatures, a...
Article
Full-text available
In this work we report the excess molar volumes, for the miscible mixtures {xc-C5H10 + (1 − x)CH3OH} and {xc-CkH2k + (1 − x)ClH2l+1OH} where k = 5, 6, 7, 8, or 10 and l = 2 or 3. The results are discussed in terms of the size of the cycloalkane ring and the type of alcohol. Key words: Excess volumes, cycloalkane + alkanol.
Book
The breadth of information included in this single volume will make it the most comprehensive coverage of waste on the market. It focuses on all of the main areas including household waste (compostable material, paper, glass, textiles, household chemicals, plastic, water, e-waste), industrial and societal waste (metals, building, tires, medical bat...
Article
The phase diagrams of the ionic liquid (IL) N-butyl-4-methylpyridinium bis{(trifluoromethyl)sulfonyl}imide ([BM(4)Py][NTf(2)]) with water, an alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol), an aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene), an alkane (n-hexane, n-heptane, n-octane), or cyclohexane have been measured at...
Article
The ionic liquid N-butyl-3-methylpyridinium tosylate ([BM3Py][TOS]) has been synthesized from β-picoline as a substrate. The work includes the characterization of the synthesized compound by elemental analysis, 1H NMR and 13C NMR spectra, water content, and by the differential scanning calorimetry. Phase diagrams for the binary systems {[BM3Py][TOS...
Article
Activity coefficients at infinite dilution were determined for 24 solutes: n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes and alcohols in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate, [OMIM][PF6], by gas–liquid chromatography at three different temperatures T=(313.15, 323.15, and 333.15)K. The partial molar exces...
Article
Liquid−liquid phase equilibria (LLE) of six ternary mixtures, {methanol (1) + tetrahydrofuran (THF) (2) + hyperbranched polymer (HBP) Boltorn U3000 (B-U3000) (3)}, {ethanol (1) + THF (2) + B-U3000 (3)}, {methanol (1) + methyl tert-butyl ether (MTBE) (2) + B-U3000 (3)}, {ethanol (1) + MTBE (2) + B-U3000 (3)}, {methanol (1) + ethyl tert-butyl ether (...
Article
Activity coefficients at infinite dilution were determined for 24 solutes (n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, alkylbenzenes, and alcohols) in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate by gas-liquid chromatography at three different temperatures T = (313.15, 323.15, 333.15) K. The partial molar excess entha...
Article
(Solid + liquid) equilibria (SLE) and (liquid + liquid) equilibria (LLE) for the binary systems ionic liquid (IL) N-butyl-4-methylpyridinium tosylate (p-toluenesulfonate) [BMPy][TOS] + an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol), or water, or an alkane (hexane, heptane, octane), or benzene, or an alkylbenzene (toluene, ethylben...
Article
Activity coefficients at infinite dilution for 19 solutes: alkanes, cycloalkanes, alk-1-enes, alk-1-ynes, benzene and alcohols in the ionic liquid N-butyl-4-methylpyridinium tosylate ([BMPy][TOS]) were determined by gas–liquid chromatography at four temperatures T=(328.15, 333.15, 338.15, and 343.15)K. The partial molar excess enthalpy values at in...
Article
A new phosphonium ionic liquid was investigated as a possible solvent for use in the separation of aromatic hydrocarbons from aliphatic hydrocarbons. The activity coefficients at infinite dilution, , for 14 solutes: n-alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, and aromatic hydrocarbons in the ionic liquid trihexyltetradecylphosphonium-bis-(2,4,...
Article
The activity coefficients at infinite dilution, γ13∞, for hydrocarbon solutes and some alcohols in the ionic liquid trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide [3C6C14P][Tf2N] have been determined by gas−liquid chromatography at temperatures T = (303.15, 308.15, 313.15, and 318.15) K. The selectivity values have been calculated...
Article
Densities of pure 1-ethyl-3-methylimidazolium ethylsulfate ionic liquid – [C2mim][EtSO4] and its mixtures with methanol have been measured with an accuracy of ±0.2kg·m−3, over the temperature range (283.15 to 333.15)K and pressure range (0.1 to 35)MPa, using a vibrating tube densimeter. Excess volumes have been calculated directly from the experime...
Article
Full-text available
This article describes some simple cryophoruses that can be made with basic laboratory equipment. Our guiding principle in these designs was "Would a high school chemistry laboratory have the resources required to make these cryophoruses?" The article also describes the use of cyclohexane as a working liquid, and shows that it is indeed better for...
Chapter
This chapter focuses on the application of key experimental techniques for the determination of the thermodynamic properties of ionic liquid–organic mixture to effectively screen ionic liquids as solvents in industrial separation processes. The acquisition of experimental liquid–liquid equilibria data for solvent–organic mixtures of interest is inv...
Chapter
This chapter discusses where a pollutant, such as fertilizer or herbicide, once introduced into the environment would end up. When any chemical is released into the air or water or sprayed on the ground, it ultimately appears in all parts of the environment, such as the upper and lower atmosphere; lakes, oceans, and soil; and all animal and vegetab...
Article
Activity coefficients at infinite dilution, , have been determined for organic solutes in the phosphonium-based ionic liquid, tributylmethylphosphonium methylsulphate at T = 308.15 K, 318.15 K and 328.15 K. The experimental activity coefficient data presented are the first to be reported for this ionic liquid, through the use of the technique of st...
Article
High pressure vapor–liquid equilibrium data for binary systems of carbon dioxide with naphthalene and benzoic acid were measured at three different temperatures for each system. Experimental temperatures and pressures ranged from 373 to 458K and 0 to 22MPa, respectively. Dew points were also measured for naphthalene in the CO2 rich region. The data...
Book
Environmental problems are becoming an important aspects of our lives as industries grow apace with populations throughout the world. Our new book Thermodynamics, Solubility and Environmental Issues addresses some of the problems and shows how chemistry can help to reduce these problems. The unifying theme is Solubility - the most important and bas...
Article
In this work, the activity coefficients at infinite dilution for 14 solutes: alkanes, alkenes, an alkyne, cycloalkanes, benzene, and methanol in the ionic liquid 1-methyl-3-octyl-imidazolium diethyleneglycolmonomethylethersulfate were determined by gas + liquid chromatography at the temperatures (288.15, 298.15, and 313.15) K. The ionic liquid had...
Article
The liquid−liquid equilibria data for the ionic liquids 1-ethyl-3-methylimidazolium octyl sulfate and 1-methyl-3-octylimidazolium diethylenglycol monomethyl ether sulfate was investigated at T = 298.2 K and atmospheric pressure to determine their potential as solvents for extracting an aromatic compound from alkanes. The cloud point method was used...
Article
The activity coefficients at infinite dilution, (where 1 refers to the solute and 3 to the solvent), for both polar and non-polar solutes (alkanes, alk-1-enes, alk-1-ynes, cycloalkanes, benzene, carbon tetrachloride, and methanol) in the ionic liquid 1-hexyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)-imide [HMIM][Tf2N] at three temperatures...
Article
Excess molar enthalpies and excess molar volumes of binary mixtures of (benzene or methanol or ethanol or 1-propanol or 1-butanol+quinoline) as a function of composition at a pressure of 1 atm and a temperature of 298.15 K have been used to test the Extended Real Solution Theory, ERAS, of nonelectrolyte solutions.The ERAS theory accounts for free v...
Article
Activity coefficients at infinite dilution, , have been determined for polar and non-polar organic solutes in the high molecular weight ionic liquid, trihexyl(tetradecyl)-phosphonium tris(pentafluoroethyl) trifluorophosphate at T = 308.15, 318.15 and 328.15 K. The experimental activity coefficient data presented are the first to be reported for the...
Article
The activity coefficients at infinite dilution, , for hydrocarbons and methanol solutes in the ionic liquid 1-butyl-3-methylimidazolium octyl sulfate, [BMIM][OcOSO3], have been determined by gas−liquid chromatography at temperatures of 298.15 K, 313.15 K, and 328.15 K. This work is part of our research focus on activity coefficients at infinite dil...
Article
The activity coefficients at infinite dilution, (where 1 refers to the solute and 3 to the solvent), for both polar and non-polar solutes in the ionic liquid 1-butyl-3-methyl-imidazolium 2-(2-methoxyethoxy) ethyl sulfate have been determined by gas-liquid chromatography. The interaction at the gas-liquid interface between the solutes and the solven...
Article
Ternary (liquid + liquid) equilibrium data are presented for mixtures of 1-hexyl-3-methylimidazolium (tetrafluoroborate or hexafluorophosphate) + benzene + (heptane or dodecane or hexadecane) at T=298.2 K. The tie line compositions of the conjugate solutions were obtained by means of density measurements and a standard density calibration curve. La...
Article
The activity coefficients at infinite dilution, , for both polar and nonpolar solutes in the ionic liquid 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl) imidate have been determined by gas−liquid chromatography at the temperatures T = 303.15 K and T = 318.15 K. The results have been used to predict the solvent potential for the hexane−be...
Article
The potential of the polar solvent, furfuryl alcohol, as a solvent in the separation of aromatics from aliphatics and other hydrocarbons, has been investigated by measuring activity coefficients at infinite dilution. The activity coefficients at infinite dilution for some alkanes, cycloalkanes, alkenes, alkynes and benzene in furfuryl alcohol have...
Article
Liquid–liquid equilibrium data are presented for mixtures of {1-hexyl-3-methylimidozolium(tetrafluoroborate or hexafluorophospate) + ethanol + (1-hexene or 1-heptene)} at T=298.2K. The data presented provides valuable insight into how variation of the anion of the environmentally friendly ionic liquid solvent can have a marked effect upon the separ...
Article
The determination of vapor pressures, p0, of compounds with low vapor pressures (10(-8) Pa < p0 < 10(3) Pa) is becoming increasingly important as a result of the need to measure p0 for environmentally sensitive compounds such as organophosphorus pesticides, biphenyls, dioxins and alkylbenzenes. Under strict conditions, the components of gas-liquid...
Article
The activity coefficients at infinite dilution for some alkanes, cycloalkanes, alkenes, alkynes and benzene in furfural have been determined by g.l.c. at T=278.15 K and T=298.15 K. The volatility of the solvent furfural, although low, was taken into account. The method used is an alternative to the pre-saturation method. The results have been used...
Article
The activity coefficients at infinite dilution, , for both polar and nonpolar solutes in an ionic liquid, 1-hexyl-3-methylimidazolium tetrafluoroborate ([HMIM+][BF4-]), have been determined by gas−liquid chromatography at T = (298.15 K and 323.15 K). This work is part of our research focus on ionic liquids. The selectivity values have been calculat...
Article
Activity coefficients for hydrocarbon solutes at infinite dilution in 1-methyl-3-octyl-imidazolium chloride have been measured using the medium pressure gas–liquid chromatography method. The hydrocarbon solutes used were n-pentane, n-hexane, n-heptane, n-octane, 1-hexene, 1-heptene, 1-octene, 1-hexyne, 1-heptyne, 1-octyne, cyclopentane, cyclohexane...
Article
Ternary liquid−liquid equilibria for the mixtures (1-methyl-3-octylimidazolium chloride + an alkanol + an alkane) at 298.2 K are reported. The alkanes used were heptane, dodecane, and hexadecane, and the alkanols were methanol and ethanol. The solubility of the alkanol is higher in the ionic liquid rich phase than in the alkane rich phase. The effe...
Article
Excess molar volumes VME were measured as a function of mole fraction at K and atmospheric pressure for {(tetrahydrofuran or tetrahydrothiophene) + (hex-1-yne, or hept-1-yne, or oct-1-yne)}. The results of the hydrogen-bonded mixtures are discussed in terms of: alkyne chain length; molecular size and temperature dependence.
Article
Liquid−liquid equilibrium results for mixtures of furfural + a chlorinated aromatic compound + an alkane at T = 298.15 K are reported, where a chlorinated aromatic compound refers to chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, or 1,2,4-trichlorobenzene and an alkane refers to n-hexane, n-dodecane, or n-hexadecane. The compositions of t...
Article
Ionic liquids, with their very low vapor pressures and unique solvent properties, are potentially useful solvents for separating organic liquid mixtures by solvent extraction or by extractive distillation. In this work, the activity coefficients at infinite dilution, , for both polar and nonpolar solutes in the ionic liquid 1-hexyl-3-methylimidazol...
Article
In this work experimental VLE data are presented for N-methylformamide + hexane, N-methylformamide + benzene, N-methylformamide + chlorobenzene, and N-methylformamide + acetonitrile at 363.15 K. The data were measured using a computer driven static vapor-liquid equilibrium device. The data were modeled with the NRTL excess Gibbs energy (g(E)) model...
Article
The liquid–liquid equilibrium data are presented for ternary mixtures {1-methyl-3-octyl-imidazoliumchloride (MeOctImCl)+benzene+an alkane} at T=298.2K. The alkanes used were heptane, dodecane, and hexadecane. The compositions of the ternary mixtures on the coexistence curve and the conjugate solutions were evaluated using densities and a standard d...
Article
Liquid−liquid equilibrium results for mixtures of furfural + an aromatic hydrocarbon + an alkane at T = 298.15 K are reported, where an aromatic hydrocarbon is benzene or methylbenzene or 1,2-dimethylbenzene or 1,3-dimethylbenzene or 1,4-dimethylbenzene and an alkane refers to n-hexane or n-dodecane or n-hexadecane. The data were measured using the...
Article
Liquid-liquid equilibrium results for mixtures of furfury alcohol + an aromatic hydrocarbon + an alkane at T = 298.15 K are reported, where an aromatic hydrocarbon refers to benzene or methyl benzene or 1,2-dimethylbenzene and an alkane refers to hexane or dodecane or hexadecane. The data presented indicate the utility of furfuryl alcohol as a solv...
Article
The excess molar enthalpies HmE, for the mixtures (N-methyl-2-pyrrolidinone + ethanol, or pentan-1-ol, or hexan-1-ol, or heptan-1-ol, or octan-1-ol, or nonal-1-ol, or decan-1-ol, or undecan-1-ol) at T=298.15 K and atmospheric pressure have been obtained using flow calorimetry. Excess molar volumes at T=298.15 K and atmospheric pressure have also be...
Article
The potential of monoethanolamine (MEA) as an extractive solvent for extractive distillation and liquid extraction was assessed. The systems studied were n-hexane + benzene, cyclohexane + ethanol, and acetone + methanol binary azeotropic systems with MEA as the solvent. Sub-atmospheric vapor-liquid equilibrium data were determined for all the syste...