Browsing by Subject "Solvent extraction"
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Item Extraction of waste water from biomass gasification(Texas Tech University, 1980-08) Kao, Chih-hengA waste water mixture from the pyrolysis of cattle manure, wood residues and corn stover was examined. Some methods of waste water treatment were screened. Activated carbon adsorption and solvent (carbontetrachloride, methylene chloride, n-butyl alcohol and methyl ethyl ketone) extraction were the methods chosen to treat the waste water. The results showed that dual solvent extraction using methyl ethyl ketone as a polar solvent to extract the valuable pollutants from the waste water and nhexane as a volatile solvent to recover the dissolved, polar solvent from the extracted water is an effective method to treat the waste water. A computer program has been developed to aid in the design of a solvent extraction column.Item Metal cation complexation and separation with macrocyclic polyether ligands(Texas Tech University, 2004-12) Vogel, Howard FAt Hanford, Washington, the Department of Energy maintains a site that contains approximately 6x10^7 gallons (2 x l0^8 liters) of waste left over from the development of nuclear weapons after WWII. This volume of material is too great to be stored in Yucca Mountain. Separation of the high-level radionuclides from the bulk of the material will allow the remainder to be treated and disposed of as low-level waste. Once separated, the high-level nuclides are then available for use in commercial applications, such as medical imaging and remote power plants. This study explores the use of crown and lariat ethers for the separation of metal ions. A large number of compounds varying in specific structural aspects are studied using isothermal titration calorimetry (ITC), which directly determines the association constant, stoichiometry, and enthalpy of each metal-ligand system. Augmenting the ITC study is the intense study of a small selection of compounds. These compounds are studied under various conditions using a variety of techniques, such as ion-selective electrodes (ISE) and solvent extraction (SE), allowing for a fuller understanding of their association behavior. The presence of metal ion is our world is ubiquitous. Some of these metals are benign, or even necessary for life. Others are harmful in minute quantities. The ability to selectively remove specific metal ions from waste streams, the environment, and our bodies will be an important process in years to come.Item Metal Ion Extraction With New Di-ionizable Ligands(2010-12) Crawford, Jennifer D.; Bartsch, Richard A.; Korzeniewski, Carol; Pappas, DimitriThis study seeks to evaluate several series of novel di-ionizable multidentate ligands for the separation of metal ions by solvent extraction. The ligands studied included calix[4]arenes, calix[4]arene-crown ethers, and acyclic polyether ligands, each containing either carboxylic acid functionalities or “acidity-tunable” N-(X)sulfonyl carboxamide moieties in which the X-group was varied. Both single species and competitive extractions of metal cations were performed using solutions of the ligands in chloroform. The study of novel di-ionizable calix[4]arene ligands sought to determine the effect of several structural variations on the ligands’ efficiency to extract lead(II), mercury(II), alkali metal cations, and alkaline earth metal cations from an aqueous phase into chloroform. These structural variations included ligand conformation, upper and lower rim functionalization, addition of a crown-ether ring to the lower rim, and identity of the ionizable groups. The ionizable groups were located either on the upper or lower rim of the calix[4]arene structure. The pH dependence of the ligand extraction efficiency was also determined in order to compare ligand acidities. The results of the study indicate that all of these structural variations have an effect on the efficiency and selectivity with which the ligands extract metal ions. Novel di-ionizable acyclic polyether ligands were utilized in solvent extraction studies of divalent metal cations. Three series of ligands containing various ionizable groups were used, in which systematic structural variations were made to determine the effect of the end-group identity and placement on ligand performance. The pH dependence of the ligand extraction behavior was investigated to elucidate information about ligand acidity. It was determined from the results of these studies that the these ligands do have a propensity to complex Pb2+ and Hg2+ in single ion extractions, and exhibit selectivity for Ba2+ in competitive extractions of alkaline earth metal cations. The identity and attachment site of the end group, as well as the identity of the ionizable groups, did have an effect on extraction efficiency, selectivity, and acidity of the ligands studied.Item New Calixarene and Cyclophane Macrocycles(2011-05) Son, Pillhun; Bartsch, Richard A.; Mayer, Michael F.; Fuertes, Michael J.; Niwayama, SatomiThe design, synthesis and analysis of new supramolecular hosts are rapidly developing areas of chemistry. This dissertation research presents the synthesis of new calix[4]arene ligands, new cyclophane derivatives and a new type of crown ether corrals accompanied by fluorescence binding analysis. A variety of calix[4]arene ligands have been developed in the past for various applications. Novel di-ionizable tetrabutoxycalix[4]arenes in four different conformations have been synthesized in this dissertation research. In contrast with the tetrabutoxycalix[4]arene ligands which are conformationally fixed, a conformationally mobile methoxy-tributoxy-calix[4]arene was synthesized. The synthetic exploration of calix[4]arene ligands was expanded into multicalix[4]arenes and cyclophane-bridged calix[4]arenes. Cyclophanes have been applied to diverse areas of supramolecular chemistry. A cyclophane with rigid α,α’-bis[(4-hydroxyphenyl]-1,4-diisopropyl-benzene components has been previously termed “corrals”. New synthetic routes, methods, techniques and ring-closure components have been applied to achieve 77 new corral derivatives, which selectively possess attractive properties, such as chirality, selective functionalization, asymmetry, and fluorescence. For some of the new cyclophane hosts synthesized fluorescence binding analysis was conducted. A total of 75 metal salt species was tested with two crown ether corrals resulting in interesting cation recognition, anion effects and selective fluorescence effects on shaking.Item Separation of alkali metal cations and alkaline earth cations using ionizable crown ethers(Texas Tech University, 1988-08) Jeon, Eok-giuProton-ionizable crown ethers are novel agents for the separation of metal ions by extraction and membrane transport processes. A series of novel crown ether carboxylic acids , crown ether phosphonic acid monoesters, and crown ether phosphonic acids which possess lipophilic pendant groups were employed for the study of extraction and membrane transport. In addition to mono- and di-ionizable macrocyclic complexing agents, monoand di-ionizable acyclic complexing agents were utilized to probe the effects of structural variation within the ionizable polyether and environmental variation upon the selectivity and effÃciency in metal ion complexation and transport. Experimental techniques of pK^ determination in dioxane-water systems, solvent extraction, and proton-coupled transport across bulk liquid membranes were utilized to assess the metal ion complexing properties of these ligands. To provide greater insight into the factors which control metal ion complexation by ionizable crown ethers in solvent extraction and membrane transport processes, thermodynamic ionization constants, ^pKa, for twenty ionizable complexing agents were determined. Thirty functionalized polyether ligands were employed in the solvent extraction of group lA and 2A metal cations. For these highly lipophilic ionizable macrocyclic multidentate ligands, the influence of structural variation upon the selectivity and efficiency of cation complexation was probed. Such structural variations included: the polyether cavity size; the lipophilic group size; the side arm length; the lipophilic group attachment site; the polarity of the lipophilic group; the ring oxygen basicity; the ring heteroatom identity; and the ionizable group identity. In addition to these parameters, an environmental variation of the organic solvent was also investigated. Competitive alkali metal transport from an alkaline aqueous source phase through a bulk liquid membrane phase into an acidic aqueous receiving phase facilitated by nineteen mono-ionizable crown ethers was investigated in three kinds of cells, i.e., Cell A (U-Tube cell), Cell B (tube-witiiin-a-beaker type cell), and Cell C (beaker-within-a-beaker type cell). In order to probe the influence of structural variations upon membrane transport, experiments were conducted for five structural parameters: variation of the polyether cavity size, variation of the lipophilic group attachment site, variation of the lipophilic group size, variation of the ring hetero atom identity, and variation of the ionizable group identity. In addition to these structural parameters, environmental variations of the organic solvent, the pH gradient between aqueous source phase pH and aqueous receiving phase pH, and the carrier concentration were also investigated, Through this complexation and transport study using forty-three functionalized organic multidentate ligands, it has been shown that ionizable crown ethers are effective agents for the solvent extraction of alkali metal and alkaline earth cations and for the proton-coupled transport of alkai metal cations across bulk liquid membranes. The selectivity and effîciency of competitive solvent extraction and membrane transport can be controlled by structural variation within the ionizable crown ethers and acyclic polyethers or by environmental variation. Such systems possess considerable potental for practical separations of specifîed alkali metal or alkaline earth cations from aqueous solutions.Item Synthesis of Novel Calix[4]arene-Based Ligands for Selective Metal Cation Extraction(Texas Tech University, 2009-08) Yang, Yanfei; Bartsch, Richard A.; Birney, David M.; Li, GuigenThe synthesis of ligands with superior binding efficiency and selectivity toward targeted metal cations is an important area of scientific endeavor. Calix[4]arene-based ligands with interesting properties in binding with various metal cation species have been prepared during the past 20 years. This dissertation research presents the design and synthesis of a variety of novel calix[4]arene-based ligands. To evaluate the metal cation binding behavior of these ligands, solvent extraction was employed for proton-ionizable ligands and an ion-selective electrode (ISE) method for non-ionizable analogues. Proton di-ionizable calix[4]arene-crown-4 ligands in three conformations were synthesized. This is part of continuing research for construction of a comprehensive library of calix[4]arene-crown ethers for various metal cations. The N-(X)sulfonyl carboxamide groups with tunable acidity are employed as novel proton-ionizable groups. By varying X from methyl to trifluoromethyl, a wide pH window was created for the ligands. Spatial arrangement of donor atoms in the macrocyclic ligands was shown to be an important factor that influences metal cation binding properties and selectivities of ligands. To further explore the impact of this factor on calix[4]arene-crown ether ligands, a series of calix[4]arene-crown-4 compounds in the cone conformation with an expanded crown ether ring was synthesized. In solvent extraction, the calix[4]arene-crown-4 ligands with an expanded crown ether ring were found to be better extractants for some heavy metal cations compared to the conventional calix[4]arene-crown-4 analogues. Design and evaluation of ionophores that can selectively bind with heavy metal cations, such as Pb2+ and Hg2+, have important potential applications. According to the soft nature of these metal cations, they are rather thiophilic than oxophilic. A relatively simple approach for enhancing ligand/metal cation interaction is the incorporation of soft donor atoms in the ligand. Compared to thiacalixarene and mercaptocalixarene, less effort has been paid to the design and synthesis of calix[4]arene-crown ethers with thiacrown fragments. A series of di-ionizable p-tert- butylcalix[4]arene-monothiacrown-5 ligands is synthesized and examined by solvent extraction. The ligands were good extractants for Hg2+ and Pb2+. Binding with these soft metal cations is accomplished in a very acidic environment. Some miscellaneous di-ionizable calix[4]arene-based ligands also are prepared. These ligands include di-ionizable calix[4]arene-1,2-crown-5 with elongated proton-ionizable groups and the upper-rim functionalized calix[4]arene-crown-5 ligands. Calix[4]arene-1,2-crowns are less studied compared to 1,3-crown analogues due to their relatively poor metal cation binding behavior. However, some 1,2-crown analogues synthesized recently in the Bartsch Research Group exhibited very good metal cation binding properties and selectivities. The study of 1,2-crowns that incorporated elongated proton-ionizable groups allows us to enhance our understanding of calix[4]arene-1,2-crowns. Some di-ionizable calix[4]arene-crown-5 compounds with proton-ionizable groups on the upper rim are also prepared. The aromatic region of calix[4]arenes could behave as a potential binding site for some soft cations. The modified upper rim has proton-ionizable groups closely located to this potential binding site and possibly an enhanced binding with these soft metal cations could be observed. Finally, some di-benzyl calix[4]arene-dithiacrowns with various crown ether ring sizes, conformations, and para-substituents were synthesized. The increment number of sulfur donor atoms in the crown ether fragment was proposed to improve the ligand binding behavior with heavy metal cations. The binding behaviors of these ligands were evaluated by ion selective electrodes (ISEs). This is the first systematic study of the metal cation binding properties of the calix[4]arene-dithiacrown ligands by this method.