Dissertations / Theses on the topic 'Cyanex 272'

This project aimed to examine the separation of cobalt and nickel using solvent extraction (SX) with the extractant CYANEX 272 (C272). It was intended to investigate the Co-Ni separation in a sulphate-based leach solution in presence of other contaminants. This is an area of interest because of the difficulty of separating metals of similar properties within the field of hydrometallurgy.  Batch tests, with varying modifiers and diluents, were carried out to examine the effect of organic phase composition on phase separation. The effect of pH on equilibrium was investigated by constructing equilibrium curves. Through various shaking tests, different separation parameters were studied. McCabe-Thiele diagrams were constructed to predict design parameters. In order to simulate a continuous 3-stage countercurrent solvent extraction, batch tests were performed. Scrubbing, as means of impurity removal was also investigated. Finally, the product’s purity was examined by the help of crystallization.  The organic feed mixture that resulted in a sufficient phase separation consisted of C272, tributyl phosphate and naphtha. At pH 4, equilibrium curves showed that equilibrium was either not reached or affected by competing metal ions. A standard equilibrium curve appearance was seen at pH 4.5, resulting in that the theoretical required stages for extraction was calculated to 3 stages (A/O=1). However, a McCabe-Thiele diagram did not give an accurate representation of the more complex case (presence of contaminants). Batch simulation results gave a cobalt recovery of 69% and 100% at pH 4.5 and 4.8, and a nickel recovery of 0% and 3%, respectively. A recommended pH-value for solvent extraction could not be stated, because the choice must be based on operation specifications. Therefore, several different aspects (Co recovery, purity, and economical etc.), must be accounted for. A similar pH-trend was shown in scrubbing, where an increase of pH resulted in an increase of metal ions’ organic concentration. For stripping, acid test results proved 24 g/L sulphuric acid to give the highest cobalt concentration, with a marginal difference in concentration of impurities. An overview of the entire SX process, indicated that extraction, scrubbing, and stripping were all successful operations. The extraction stage showed a Co and Ni recovery of 99% and 0.02%, respectively, and a separation factor of 14250. Distribution results indicated that Al was difficult to remove and was transferred with Co into the product. Therefore, this element must be removed before SX. From noticing an increase of Co:Ni ratio throughout the process, solvent extraction was considered an effective separation method for cobalt and nickel separation. A considerably high purity of cobalt sulphate was produced. However, impurities Al and Ca were also detected in the product. Increasing the acetone volume in crystallization resulted in an increase of Co purity. An increase of the cobalt sulphate crystals formed was observed when increasing the acetone volume, where no impurities were detected.

The bulk of the world's known nickel reserves are contained in laterite ores but sulphidic ores remain the main source of the Western world's nickel production. With the continuing increase in nickel consumption and the depletion of sulphidic ores, the traditional source of nickel, the extraction of nickel from lateritic ores has been the subject of research interest worldwide. Advances in pressure acid leaching (PAL) technology have resulted in significant commercial attempts to extract nickel from these ores. Leaching the ore with sulphuric acid at elevated temperatures and pressures allows almost complete dissolution of the nickel and cobalt, a valuable byproduct of these ores, but yields highly contaminated pregnant leach solutions. Separating and purifying the nickel and cobalt from these solutions remains a hindrance to full commercial production. Several purifying techniques have been commercialised but all suffer from continuing technical problems. Among them, however, the direct solvent extraction (DSX) technique offers several advantages. Direct solvent extraction involves the separation of the nickel and cobalt directly from the partially neutralised pregnant liquor stream (PLS) by solvent extraction with Cyanex(R) 272 as the extractant. However certain contaminants adversely affect the solvent extraction process. Among them is chromium and little is known about the solvent extraction behaviour of this metal. The present work investigated the solvent extraction of chromium with Cyanex(R) 272. It was found that the solvent extraction behaviour of chromium(III) and chromium(VI), both of which could be found in PAL-generated PLS, are distinctly different.For chromium(III), solvent extraction tests showed that (a) it is extracted in the pH range 4-7; (b) the extraction is partly influenced by diffusion; (c) the apparent equilibration time is significantly longer than most transition metals; (d) increases in temperature from 22 to 40 C resulted in increases in the extraction; (e) the pH0.5 increases in the order nitrate < chloride < sulphate in the presence of these anions; (f) the presence of acetate depresses extraction of chromium(III) when the solution is allowed to stand before extraction; (g) in the PLS, chromium(III) precipitated at lower pH than that predicted by the solubility product principle; and (h) the pH0.5 decreases as the Cyanex(R) 272 concentration increases. Chromium(III) is initially extracted by solvation of its inner sphere complex, which then undergoes further reaction in the organic phase leading to the formation of a much more stable species that is difficult to strip. A reaction scheme together with a description of both the initially extracted and resulting stable species is proposed. Extraction of chromium(VI), on the other hand, (a) occurs at pH less than 2 by solvation of chromic acid; (b) is independent of the aqueous phase composition; (c) does not occur in the pH range (3-6) used in the separation of nickel and cobalt. The latter is irrespective of temperature up to 40 C, the use of industrial PLS as the aqueous phase or the presence of an anti-oxidant in the organic phase. The stripping of chromium(III) from a loaded organic phase can be achieved using 1-4 mol L-1 mineral acids provided the stable organic species have not formed making industrial scale stripping of chromium(III) from Cyanex(R) 272 difficult. The exact composition of the aqueous phase during extraction affects the stripping efficiency.

The bulk of the world's known nickel reserves are contained in laterite ores but sulphidic ores remain the main source of the Western world's nickel production. With the continuing increase in nickel consumption and the depletion of sulphidic ores, the traditional source of nickel, the extraction of nickel from lateritic ores has been the subject of research interest worldwide. Advances in pressure acid leaching (PAL) technology have resulted in significant commercial attempts to extract nickel from these ores. Leaching the ore with sulphuric acid at elevated temperatures and pressures allows almost complete dissolution of the nickel and cobalt, a valuable byproduct of these ores, but yields highly contaminated pregnant leach solutions. Separating and purifying the nickel and cobalt from these solutions remains a hindrance to full commercial production. Several purifying techniques have been commercialised but all suffer from continuing technical problems. Among them, however, the direct solvent extraction (DSX) technique offers several advantages. Direct solvent extraction involves the separation of the nickel and cobalt directly from the partially neutralised pregnant liquor stream (PLS) by solvent extraction with Cyanex(R) 272 as the extractant. However certain contaminants adversely affect the solvent extraction process. Among them is chromium and little is known about the solvent extraction behaviour of this metal. The present work investigated the solvent extraction of chromium with Cyanex(R) 272. It was found that the solvent extraction behaviour of chromium(III) and chromium(VI), both of which could be found in PAL-generated PLS, are distinctly different.
For chromium(III), solvent extraction tests showed that (a) it is extracted in the pH range 4-7; (b) the extraction is partly influenced by diffusion; (c) the apparent equilibration time is significantly longer than most transition metals; (d) increases in temperature from 22 to 40 C resulted in increases in the extraction; (e) the pH0.5 increases in the order nitrate < chloride < sulphate in the presence of these anions; (f) the presence of acetate depresses extraction of chromium(III) when the solution is allowed to stand before extraction; (g) in the PLS, chromium(III) precipitated at lower pH than that predicted by the solubility product principle; and (h) the pH0.5 decreases as the Cyanex(R) 272 concentration increases. Chromium(III) is initially extracted by solvation of its inner sphere complex, which then undergoes further reaction in the organic phase leading to the formation of a much more stable species that is difficult to strip. A reaction scheme together with a description of both the initially extracted and resulting stable species is proposed. Extraction of chromium(VI), on the other hand, (a) occurs at pH less than 2 by solvation of chromic acid; (b) is independent of the aqueous phase composition; (c) does not occur in the pH range (3-6) used in the separation of nickel and cobalt. The latter is irrespective of temperature up to 40 C, the use of industrial PLS as the aqueous phase or the presence of an anti-oxidant in the organic phase. The stripping of chromium(III) from a loaded organic phase can be achieved using 1-4 mol L-1 mineral acids provided the stable organic species have not formed making industrial scale stripping of chromium(III) from Cyanex(R) 272 difficult. The exact composition of the aqueous phase during extraction affects the stripping efficiency.

The present work examined the synergistic extraction solvent applied to the separation of calcium and nickel present in synthetic aqueous sulfuric solutions using the commercial organophosphorus extractants D2EHPA (di-2-ethylhexyl phosphoric acid) and Cyanex 272 (bis-2,4,4 -trimethylpentyl phosphinic acid), diluted in n-heptane. The objective was to evaluate the effects of competition between metals in the aqueous phase and between the extractants in the organic phase, both individually and simultaneously. To this end, extractions were analyzed using combinations of mono and bicomponents aqueous phases (only calcium or nickel, and both metals together), and mono and bicomponents organic phases (D2EHPA or Cyanex 272 alone, and both extractants together). Extraction tests were performed at a temperature of (25±2)°C and the volume ratio of phases of unity (A/O = 1), varying the pH from 3.5 to 7.0. The operational parameters used in the analysis of the results were the percentage of metals extraction and calcium/nickel selectivity. Samples of the organic phase were analyzed by Fourier Transform Infrared Spectroscopy (FT-IR) and Raman spectroscopy, in order to infer on the structures of the organometallic species formed during extraction. With regard to competition in the aqueous phase, it was observed that the presence of nickel, at equimolar concentrations of calcium does not interfere with calcium extraction independently of the extractor system used (Cyanex 272, D2EHPA, or D2EHPA + Cyanex 272). The nickel extraction in the presence of calcium is shifted to higher pH values using D2EHPA, as well as with the mixture of extractants. With Cyanex 272, the nickel extraction in the presence of calcium also was changed, but in a small proportion. With respect to competition in the organic phase, it was observed that the extraction curves of metals using the mixture of extractants are similar to those obtained when using only D2EHPA, indicating that it is the main reagent for the extraction of metals by mixing Cyanex 272 + D2EHPA. However, the presence of Cyanex 272 in the bicomponent organic phase favors nickel extraction compared to extraction by D2EHPA, in the presence of calcium, from pH 5, even if the metal extraction by Cyanex 272 separately is not significant in the range of pH evaluated. The mixture Cyanex 272 + D2EHPA is more selective for calcium to nickel (3.5 pH 5.0) compared to extractants separately, reaching a maximum value at pH 4.5. In this pH, the separation factor Ca /Ni with the mixture of extractants is about 17 times higher than with D2EHPA and almost 800 times higher than with Cyanex 272. This result is due to the synergism occurred between extractants, therefore the extractor system proposed is more efficient than the extractants used individually in the evaluated conditions. The FT-IR spectrums of Cyanex 272, D2EHPA and n-heptane obtained corroborated literature, but the analysis of samples loaded organic phase under the conditions studied was inconclusive about the structures formed due to the low concentrations of organic complexes obtained.
O presente trabalho avaliou a extração por solventes sinérgica aplicada à separação entre cálcio e níquel presente em soluções aquosas sulfúricas sintéticas utilizando-se os extratantes organofosforados comerciais D2EHPA (di-2-etilhexil ácido fosfórico) e Cyanex 272 (bis-2,4,4-trimetilpentil ácido fosfínico), diluídos em n-heptano. O objetivo consistiu em avaliar os efeitos de competição entre os metais na fase aquosa e entre os extratantes na fase orgânica, tanto individual quanto conjuntamente. Para tal, foram analisadas extrações utilizando-se combinações entre fases aquosas mono e bicomponentes (somente cálcio ou níquel, e ambos os metais conjuntamente) e fases orgânicas mono e bicomponentes (somente D2EHPA ou Cyanex 272, e ambos extratantes conjuntamente). Os ensaios de extração foram realizados a temperatura de (25±2)°C e relação volumétrica entre as fases aquosa e orgânica (A/O) unitária, variando-se o pH de 3,5 a 7,0. Os parâmetros operacionais usados na análise dos resultados foram o percentual de extração dos metais e a seletividade cálcio/níquel. Amostras da fase orgânica foram analisadas por Espectrometria de infravermelho por transformada de Fourier (FT-IR) e Espectroscopia Raman, com o intuito de inferir sobre as estruturas organometálicas formadas durante a extração. No que se refere à competição na fase aquosa, tem-se que a presença de níquel, em concentrações equimolares à de cálcio, não interfere na extração de cálcio independentemente do sistema extrator usado (Cyanex 272, D2EHPA ou Cyanex 272 + D2EHPA). Já a extração de níquel na presença de cálcio é deslocada para maiores valores de pH utilizando o D2EHPA e também a mistura de extratantes. Com o Cyanex 272, a extração de níquel na presença de cálcio também sofre alteração, mas em pequena proporção. Com relação à competição na fase orgânica, observou-se que as curvas de extração dos metais utilizando-se a mistura de extratantes são semelhantes àquelas obtidas ao se usar somente D2EHPA, indicando ser esse reagente o principal responsável pela extração dos metais pela mistura Cyanex 272 + D2EHPA. No entanto, a presença de Cyanex 272 na fase orgânica bicomponente favorece a extração de níquel comparada à extração pelo D2EHPA, em presença de cálcio, a partir de pH 5, mesmo que a extração do metal pelo Cyanex 272 separadamente não seja considerável na faixa de pH avaliada. A mistura Cyanex 272 + D2EHPA é bastante seletiva ao cálcio frente ao níquel (3,5 pH 5,0) comparado aos extratantes separadamente, atingindo valor máximo em pH 4,5. Nesse pH, o fator de separação Ca/Ni com a mistura de extratantes é cerca de 17 vezes maior que com o D2EHPA e quase 800 vezes maior que com o Cyanex 272. Este resultado deve-se ao sinergismo ocorrido entre os extratantes, sendo o sistema extrator proposto superior aos extratantes usados individualmente nas condições avaliadas. O espectro FT-IR do Cyanex 272, D2EHPA e n-heptano puros foram obtidos e concordaram com a literatura, porém as análises das amostras de fase orgânica carregadas com organometálicos nas condições estudadas foram inconclusivas sobre as estruturas formadas em decorrência das baixas concentrações de organocomplexos obtidas.

O minério limonítico de níquel é considerado uma fonte de níquel e cobalto a partir de mineração. No entanto, o minério é heterogêneo e a concentração dos metais varia conforme a localização. Sendo assim, é necessário o desenvolvimento de uma metodologia que permita determinar os parâmetros de operação de um processo de separação de metais levando em consideração a composição de cada minério. No processo hidrometalúrgico, diversas técnicas de purificação ou separação dos metais podem ser usadas. O presente trabalho estudou o uso da extração por solventes para tratar o licor baseado no lixiviado de minério limonítico de níquel. No processo de extração por solventes foram determinados os parâmetros de extração dos metais como: pH, concentração do extratante na fase orgânica e diluído em querosene, relação entre as fases aquosa e orgânica (A/O) e número de contatos contracorrente teóricos para extração do metal. A extração de 100% do ferro utilizando Cyanex 272 foi determinada em pH 2, concentração do extratante 25% em volume diluído em querosene, relação A/O 1/3 e três contatos contracorrente. Durante a extração do ferro também houve coextração de 27% do cobalto. Foi possível recuperar o cobre da solução através da extração utilizando Acorga M5640 em pH 2, concentração do extratante na fase orgânica igual 5% v/v, relação entre as fases 1/1 e um contato contracorrente. O alumínio e o zinco foram extraídos em pH 3,5, utilizado Cyanex 272 como extratante na concentração 25% em volume, relação A/O 1/2 e dois contatos contracorrente. A fim de obter uma solução aquosa contendo apenas níquel em solução, a última etapa foi a remoção dos metais remanescentes na solução (cobalto, cromo, magnésio e manganês) utilizando Cyanex 272. O pH para essa extração foi 5, a concentração do extratante 20% v/v, relação entre as fases 1/1 e cinco contatos contracorrente. Ao final, foi possível obter uma solução aquosa contendo níquel em solução na concentração 2,52g/L, o que corresponde a 100% do níquel presente na solução sintética. Além do níquel, 0,19 g/L de magnésio e 0,008g/L de cromo permaneceram na solução final.
Nickel limonite ore is a source of nickel and cobalt. However, the ore is heterogeneous and concentration changes according the location of the ore. Therefore, determination of the operating parameters is required to separate the metals taking into account the composition of these ores. Hydrometallurgical process is used to treat leach liquor from ores. This work studied the treatment of synthetic solution based on leach liquor of nickel limonite ore by solvent extraction. During the study was determinated the metals extraction parameters as pH, extractant concentration in the organic phase, aqueous and organic ratio (A/O) and number of theoretical extraction stages. The extraction of iron was 100% using Cyanex 272 at pH 2, extractant concentration 25% (v/v) and three extraction stages at an A/O ratio 1/3. Nevertheless, during the extraction of iron, cobalt was co-extracted. The cobalt lost was 27% at the parameters used to extract. It was possible to recover copper from the synthetic solution using Acorga M5640 as extractant at pH 2, extractant concentration 5% v/v, one extraction stage and an A/O ratio 1/1. Aluminium and zinc were removed from synthetic solution at pH 3.5, organic phase with 25% v/v of Cyanex 272 and two extraction stages at an A/O ratio 1/2. The last part of work was removed cobalt, chromium, magnesium and manganese from the aqueous solution. The reason is staying just nickel in the final solution. Cyanex 272 at pH 5 and 20% v/v concentration was used and five extraction stages and an A/O ratio 1/1 was necessary to extract the metals. The finally solution was composed by 2.52g/L of nickel, corresponding 100% of nickel from synthetic leach liquor of nickel limonite ore. In addition, 0.19g/L of magnesium and 0.008g/L of chromium staying at solution.

The purification of aqueous solutions simulating leach liquors of sulfuric acid lateritic ores containing calcium, cobalt, copper, magnesium, manganese, nickel and zinc employing the solvent extraction technique using the extractant Cyanex 272 and mixtures of Cyanex 272 with versatic acid, Cyanex 301, naphthenic acid, mixture of carboxylic acids (MAC) and D2EHPA, diluted in n-heptane, was investigated in the present work. The main objective was to develop an organic extraction system formed by combining suitable extractants aiming to obtain a liquor purity in conditions such that allow its direct routing to the nickel eletrodeposition step. The solvent extraction tests were carried out at 50°C maintaining the volume ratio of the aqueous and organic phases (A/O) at unit, and varying the conditions of acidity of the liquor in the pH range from 2 to 7 (the pre-treatment step of liquor, when solely Cyanex 272 was used as extractant), and from 3.8 to 7.0 (in the purification step of nickel, when mixtures of extractants were used). The liquor was pre-purified in relation to the metals Co, Cu, Mn and Zn at pH = 3.88 and 20%v/v Cyanex 272, so that remain in the raffinate about 98.5% nickel, 76% calcium and 64% magnesium. Potential extractants systems have been identified: versatic acid (10%v/v), naphthenic acid (10%v/v), MAC (5 and 10%v/v) and D2EHPA (5 and 10%v/v) mixed with Cyanex 272 (20%v/v), which were found to be susceptible to promote the purification of liquor to nickel against alkaline earth metals calcium and magnesium. The combination of 5%v/v D2EHPA with 20%v/v Cyanex 272, at pH 4.8, was identified as the most suitable for the purification of organic liquor extractor system for extracting preferably high levels of calcium (about 72%) and magnesium (about 60%) over nickel (extractions around 2%), thus allowing to obtain a raffinate stream with about 96% nickel that can be routed directly to step eletrodeposition.
A purificação de soluções aquosas simulando licores da lixiviação sulfúrica de minérios lateríticos contendo cálcio, cobalto, cobre, magnésio, manganês, níquel e zinco empregando-se a técnica de extração por solventes utilizando-se o extratante Cyanex 272 e misturas de Cyanex 272 com ácido versático, Cyanex 301, ácido naftênico, misturas de ácidos carboxílicos (MAC), e D2EHPA, diluídos em n-heptano, foi investigada no presente trabalho. O objetivo principal consistiu no desenvolvimento de um sistema extrativo orgânico formado pela combinação mais apropriada entre extratantes visando-se obter um licor em condições de pureza tal que permita seu encaminhamento direto à etapa de eletrorrecuperação de níquel. Os ensaios de extração por solventes foram conduzidos a 50°C, mantendo-se a razão entre os volumes das fases aquosa e orgânica (A/O) unitária, e variando-se a condição de acidez do licor na faixa de pH entre 2 e 7 (na etapa de Pré-tratamento do licor, quando se utilizou somente Cyanex 272 como extratante), e entre 3,8 a 7,0 (na etapa de Purificação de níquel, quando se utilizou misturas entre extratantes). O licor foi pré-purificado em relação aos metais Co, Cu, Mn e Zn, em pH = 3,88 e 20%v/v de Cyanex 272, de forma que permanecem no refinado cerca de 98,5% de níquel, 76% de cálcio e 64% de magnésio. Foram identificados os seguintes potenciais sistemas extratores: ácido versático (10%v/v), ácido naftênico (10%v/v), MAC (5 e 10%v/v) e D2EHPA (5 e 10%v/v) misturados com Cyanex 272 (20%v/v), suscetíveis de promover a purificação do licor em relação ao níquel frente aos metais alcalinos terrosos, cálcio e magnésio. A combinação de 5%v/v de D2EHPA com 20%v/v de Cyanex 272, em pH = 4,8, foi identificada como o sistema extrator orgânico mais adequado para purificação do licor, por extrair preferencialmente elevados teores de cálcio (aproximadamente 72%) e magnésio (cerca de 60%), em detrimento do níquel (extrações em torno de 2%), permitindo a obtenção de um refinado com aproximadamente 96% de níquel passível de ser encaminhado diretamente para a etapa de eletrorrecuperação.

Memoria para optar al título de Químico
En esta Memoria de Titulo se estudió la transferencia del lantano (III), cerio (III), praseodimio (III) y neodimio (III), desde una fase acuosa de alimentación hacia una fase acuosa de retroextracción, por medio del transportador órgano fosforado CYANEX 272 contenido en una membrana liquida emulsificada. En primera instancia se estudió el comportamiento ácido base de cuatro extractantes (D2EHPA, PC-88A, CYANEX 272, CYANEX 301) permitiendo conocer sus pKa aparentes y su disponibilidad para reaccionar con los iones Tierras Raras (TR) a ciertos pH. A partir de este conocimiento y las reacciones de extracción propiamente tales fue posible proponer la utilización de una fase acuosa de alimentación tamponada con el ácido 3-cloropropiónico a pH 4. A través de los experimentos de extracción por solvente de cada uno de los iones TR con los cuatro extractantes en estudio, se determinó que el extractante más adecuado para el proceso fue el CYANEX 272, debido a su alta capacidad de extracción y mayor selectividad con los cuatro iones TR. Si bien en un principio todos los experimentos se realizaron con alimentaciones monometálicas, después fue preciso probar el grado de competencia que se generaría al realizar la extracción de los iones lantánidos desde una alimentación polimetálica. Los resultados fueron coincidentes con los experimentos de extracción individuales de los iones TR, en donde el lantano es el ión que menos se extrajo en comparación con los otro tres. Por otro lado, los experimentos de retroextracción revelaron que ion cerio presentaba el menor grado de transferencia hacia la fase acuosa interna. Todos estos conocimientos generados revelaron que la dupla Nd-Pr era difícil de separar con las condiciones ya establecidas. Por esta razón se agregó EDTA como agente quelante a una alimentación que contenía estos dos iones en iguales concentraciones (2mM), lográndose un coeficiente de selectividad máximo (SPr/Nd) de 1,7. Los experimentos de extracción por solvente (SX) generaron el conocimiento base para los experimentos de transporte de los cuatro iones lantánidos con CYANEX 272 a través de las Membranas Líquidas Emulsificadas (MLE). Previo al inicio de los experimentos de transferencia fue necesario lograr una doble emulsión de estabilidad adecuada en función de las concentraciones variables de sus componentes: transportador CYANEX 272, tensoactivo SPAN 80, Ln+3 (lantánidos) total y HCl en la fase acuosa de retroextracción. A partir del estudio de estabilidad, se observó que la concentración del tensoactivo SPAN 80 presentó el efecto más crítico, donde una cantidad insuficiente produjo pérdida de la fase acuosa interna, disminuyendo el rendimiento de extracción. Por otro lado, una cantidad excesiva de SPAN 80 provocó el hinchamiento de la emulsión primaria. Como consecuencia de esto la fase acuosa interna que contiene al ion de interés se diluye o pierde pureza. En términos generales, para conservar el volumen de 75 mL de emulsión primaria, formada por 25 mL de fase acuosa interna más 50 mL de fase orgánica, es necesario utilizar alrededor de 1,2% p/v de SPAN 80, cuando la concentración en la alimentación de cada uno de los ETR es 0,5 mM. Para concentraciones mayores se necesita aproximadamente entre 2-2,1% p/v de tensoactivo. Con los experimentos preliminares de transferencia de los iones TR en estudio, se pudo determinar que los elementos lantano, cerio, praseodimio y neodimio fueron extraídos eficientemente en el orden del 90% desde la alimentación, mientras que fueron transportados a través de la membrana hacia la fase acuosa interna en un rango entre 40-60%. Posteriormente, un estudio cinético de la extracción de cada uno de los ETR, permitió observar que durante los primeros 5 min los iones cerio, praseodimio y neodimio experimentaron un rápido decaimiento en su concentración en la fase acuosa externa, mientras que para el ion lantano se requirió al menos de 10 min. Finalmente, para lograr un enriquecimiento de cada uno de los iones metálicos mediante MLE desde una solución polimetálica, se realizaron dos diseños experimentales, uno de tipo screening y otro de optimización. Los resultados del primer diseño indicaron que el factor tiempo fue el único que presentó un efecto significativo sobre los porcentajes de extracción y transferencia de los ETR a través de la doble emulsión. En el segundo diseño los resultados indicaron que la presencia de EDTA en la fase acuosa externa tuvo un efecto negativo sobre el grado de transferencia de los iones TR hacia la fase orgánica.
In this work the transference of lanthanum (III), cerium (III), praseodymium (III) and neodymium (III) were studied, from a feed aqueous phase toward a backextraction aqueous phase by means of the organophosphorous CYANEX 272 carrier contained into an emulsified liquid membrane. In the first instance the acid-base behavior of the four extractants (D2EHPA, PC-88A, CYANEX 272 and CYANEX 301) were studied allowing to know their apparent pKa and through it the availability to react with the rare earth ions (RE) at certain pH. From this knowledge and the actual such extraction reactions it was possible to propose the use of a buffered feed aqueous phase with 3-cloropropionic acid at pH 4. Through the solvent extraction experiments for each one of the RE with the considered four extractants, it was determined that the most appropriated extractant for the process was CYANEX 272, owing to its high extraction capacity and better selectivity for the four RE ions. Although at first all experiments were performed with monometallic feeds, afterward it was necessary to test the degree of competition that would be generated to perform the extraction of lanthanide ions from a polymetallic feed solution. The results were consistent with the individual extraction experiments of the RE ions, wherein lanthanum is the lesser extracted ion compared with the other three ones. On the other hand, the backextraction experiments showed that the cerium ion had the lowest degree of transference toward the internal aqueous phase. All this generated knowledge revealed that the pair Nd-Pr was difficult to separate at the established conditions. For this reason, EDTA as a chelating agent was added to the feed solution that contained these two ions at identical concentrations (2 mM), achieving a maximum selectivity coefficient (SPr/Nd) of 1.7. The solvent extraction (SX) experiments generated the base knowledge for the transport experiments of the four lanthanide ions with CYANEX 272 through Emulsified Liquid Membranes (ELM). Before starting the transfer experiments it was necessary to achieve a satisfactory stability of the double emulsion as a function of the variation of the component concentrations: carrier CYANEX 272, surfactant SPAN 80, total Ln3+ (lanthanides) and HCl in the backextraction aqueous phase. From this stability study it was observed that the concentration of SPAN 80 surfactant showed the most significant effect, where an insufficient amount caused the loss of the internal aqueous phase, decreasing the efficiency of extraction. On the other side, an excessive amount of SPAN 80 caused a swelling degree of the primary emulsion. As a consequence the internal aqueous phase that contains the ion of interest is diluted or lost its purity. In general terms, for keeping the volume of 75 mL of the primary emulsion, consisting of 25 mL of internal aqueous solution plus 50 mL of the organic solution, it is necessary to use about 1.2% w/v of the SPAN 80, when the concentration of each the REE in the feeding is 0.5 mM. For higher concentrations of the total REE about 2 to 2.1% w/v of surfactant are needed, approximately. From the preliminary experiments related with the transfer study of the RE ions, it was determined that the lanthanum, cerium, praseodymium and neodymium elements are removed efficiently in the order of 90% from the feed solution, while they were transported across the membrane toward the internal aqueous phase in the range of 40-60%. Afterward, a kinetic study of the extraction of each one of the REE, allowed to note that during the first 5 min of the carrying out tests the cerium, praseodymium and neodymium ions experimented a fast decline in the concentration in the external aqueous phase, whereas for the ion lanthanum at least 10 min was required. Finally, to achieve an enrichment of each one of the metal ions from a polymetallic solution by means MLE, two experimental designs were conducted, a screening one and another one related with the optimization type. The results of the first design indicated that the time factor was the unique significant effect on the extraction and transfer rates of the REE through the double emulsion. In the second design the results indicated that the presence of EDTA in the external aqueous phase has a negative effect on the transfer degree of the RE ions towards the organic phase.
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Memoria para optar al título de Químico
En esta memoria de título se estudió la síntesis y caracterización de nanopartículas de magnetita funcionalizadas con los extractantes CYANEX 272 Y LIX 860 con el objeto de estudiar su comportamiento como material adsorbente de iones lantánidos livianos y cobre, respectivamente. En primera instancia se realizó la síntesis de nanopartículas de magnetita, mediante el método de co-precipitación, y su posterior recubrimiento con ácido oleico. Luego se llevó a cabo el proceso de funcionalización, que consistió en contactar las nanopartículas oleato-recubiertas, previamente dispersas en un solvente, con el extractante saponificado, bajo una alta agitación, permitiendo la interacción de las cadenas hidrocarbonadas entre el oleato y el extractante utilizado. Todo este proceso se realizó en condiciones experimentales que permiten la evaporación de la fase dispersante, la cual se reemplaza posteriormente por una fase acuosa. La elección de la fase dispersante resultó del estudio de 5 solventes, que fueron probados en este proceso, considerando sus constantes dieléctricas, punto de ebullición y solubilidad en agua, observando rendimiento de síntesis y comportamiento de dispersión en fase acuosa. Los resultados indicaron que el solvente más adecuado era el metanol. La dispersión del producto obtenido en la fase acuosa es un aspecto muy relevante ya que se busca una nanopartícula que sea capaz de mantenerse estabilizada en fase acuosa, para que posteriormente pueda actuar como material adsorbente de iones lantánidos y cobre. Por este motivo, se realizó un estudio de la estabilidad mediante la determinación del potencial zeta de las nanopartículas funcionalizadas con CYANEX 272 y con LIX 860, a distintos valores pH y concentraciones de NaNO3. Los resultados indicaron que utilizando una fase acuosa de concentración 0,01 M de NaNO3 a pH 4 se logra una buena estabilidad y dispersión de ambas NPM funcionalizadas. Una vez generados los dos tipos de nanopartículas funcionalizadas, una con el extractante CYANEX 272 y otra con el LIX 860, se procedió a su caracterización mediante las técnicas de IR, TGA, SEM, TEM, VSM y titulación potenciométrica. Los resultados indicaron una morfología de tendencia esférica de 10 a 12 nm de diámetro, aproximadamente, mientras que el porcentaje en masa de recubrimiento orgánico sobre las nanopartículas fue cercano al 20%. Además, se confirmó la presencia de los enlaces químicos propios del oleato quimiadsorbido y de los extractantes CYANEX 272 y LIX 860 adheridos a la superficie de las nanopartículas, indicando el recubrimiento efectivo de ellas. Mediante la obtención de las curvas de histéresis y de los valores de saturación magnética de las nanopartículas funcionalizadas, se comprobó el carácter superparamagnético y su respuesta adecuada a un campo magnético ejercido por un imán externo. Finalmente, se realizaron diferentes pruebas experimentales de adsorción de los elementos La, Ce, Pr, Nd y Sm con las NPM-CYANEX 272 y de cobre con las NPM-LIX 860. El estudio consideró la realización de pruebas cinéticas con el objeto de determinar a qué tipo de orden de reacción siguen, de pseudo primer orden (Lagergren) o de pseudo segundo orden. Además, se consideró un estudio de equilibrio de adsorción aplicando los modelos teóricos de equilibrio de Langmuir y Freundlich. Los resultados indicaron que en ambos casos el modelo de pseudo segundo orden es el que mejor representa el comportamiento cinético de adsorción. En cuanto a los equilibrios de adsorción, se determinó que los elementos cerio y lantano son interpretados de manera más apropiada por la isoterma de adsorción de Langmuir, mientras que para neodimio y praseodimio, lo más apropiado es Freundlich. En el caso de la adsorción de cobre no se logró identificar, de manera clara, el tipo de adsorción llevado a cabo en las NPM-LIX 860. Las capacidades de carga máxima logradas fueron de 4 mgLn+3/gNPM en el caso de la adsorción de elementos lantánidos con NPM-CYANEX 272 y de 6 mgCu+2/gNPM en el de la adsorción de cobre con NPM-LIX 860. Los resultados obtenidos mediante este estudio permitieron dar cumplimiento al principal objetivo planteado en esta memoria de título, referido a la síntesis de nanopartículas funcionalizadas y su uso como material adsorbente de iones lantánidos livianos y cobre
In this work, the synthesis and characterization of magnetite nanoparticles functionalized with CYANEX 272 and LIX 860 were studied in order to understand their behavior as sorbent material of light lanthanide ions and copper, respectively. At first, the synthesis of magnetite nanoparticles by co-precipitation method and subsequent coating with oleic acid was performed. Then the functionalization process was carried out, which consist in contacting the previously coated nanoparticles dispersed in a solvent with the saponified extractant, under fast agitation, allowing interaction of the hydrocarbon chains between oleate and the respective extractant. All this process was done in experimental conditions allowing the evaporation of the dispersing phase, which is then replaced by an aqueous phase. Considering their dielectric constants, boiling point and solubility in water, five solvents were tested as dispersing phase, being observed the yield of synthesis and its dispersion behavior in aqueous phase. The results indicated that the most suitable solvent was methanol. Dispersion of the obtained product in aqueous phase is a very important aspect, because is needed a nanoparticle that be able to keep stabilized in aqueous phase, by this way the can act as sorbent for lanthanide ions and copper. For this reason, a study of stability was conducted by determining the zeta potential of functionalized nanoparticles with CYANEX 272 and LIX 860 at different pH values and concentrations of NaNO3. The results indicated that using an aqueous phase of 0.01 M NaNO3 at pH 4 a good stability and dispersion for both functionalized NMP are achieved. Once both types of functionalized nanoparticles are generated, one with the extractant CYANEX 272 and the other one with LIX 860, their characterization by the techniques IR, TGA, SEM, TEM, VSM and potentiometric titration were conducted. The results indicated a spherical morphology with a 10 to 12 nm in diameter, while the weight percentage of organic coating on the nanoparticles was close to 20%. Moreover, the presence of chemical bonds on chemisorbed oleate and CYANEX 272 and LIX 860 extractants attached to the surface of the nanoparticles is confirmed, indicating their effective coating. By obtaining hysteresis curves and magnetic saturation values of the functionalized nanoparticles, the superparamagnetic character and a suitable response to a magnetic field exerted by an external magnet was verified. Finally, several adsorption tests of the elements La, Ce, Pr, Nd and Sm with NPM-CYANEX 272 and copper with NPM-LIX 860 were made. The study considered performing of kinetic tests in order to determine what kind of reaction order model is followed, pseudo first order (Lagergren) or pseudo second order. It was also considered a study of adsorption equilibrium using the theoretical models of Langmuir and Freundlich. The results indicate that in both cases the pseudo-second order model represents in best way the adsorption kinetic behavior. Regarding the adsorption equilibrium, it was determined that for cerium and lanthanum elements, a Langmuir adsorption isotherm fitted better the experimental results, whereas for neodymium and praseodymium, was the Freundlich model. In the case of copper adsorption, a clear type of adsorption carried out with NPM-LIX 860 was not identified. The achieved maximum load capacities were 4 mgLn3+/gMNP in the case of adsorption of lanthanide elements with MNP-CYANEX 272 and 6 mgCu2+/gMNP of copper ions with MNP-LIX 860. The obtained results through this study allowed to accomplish the main objective proposed in this work, based on the synthesis of functionalized nanoparticles and their use as sorbent material for light lanthanide ions and copper

Memoria para optar al Título de Químico
Autorizada por el autor, pero con restricción para ser publicada a texto completo hasta diciembre de 2014, en el Portal de Tesis Electrónicas
Las emulsiones son un tipo de sistemas de fases dispersas, se encuentran en forma abundante en nuestro alrededor y comúnmente son utilizados para el confort del hombre en la vida diaria, en la industria de los alimentos, en la industria farmacéutica, en la industria cosmética y en la industria química. Según el tipo de dispersión las emulsiones se clasifican como aquellas del tipo agua en aceite (w/o) o aceite en agua (o/w). Es posible obtener dispersiones más complejas con fines más específicos, tales como las emulsiones múltiples del tipo w/o/w u o/w/o, que requieren, en primer lugar, de la formación de una emulsión primaria estable y luego su dispersión en la fase externa. Estas emulsiones dobles generan una membrana líquida activa, capaz de transferir ciertos elementos entre dos fases extremas, miscibles entre sí pero separadas por la fase intermedia inmiscible. Al dispersar dos fases líquidas inmiscibles, que poseen una elevada fuerza de atracción entre sus propias moléculas, se genera una gran área de interfase produciendo un sistema termodinámicamente inestable, lo que conlleva la ruptura de la emulsión en un determinado tiempo. El grado de inestabilidad del sistema depende de la magnitud de la energía libre interfacial por unidad de área, o la mínima cantidad de trabajo requerido para crear una unidad de área de interfase, denominada tensión interfacial. Para estabilizar los sistemas dispersos o emulsiones se debe agregar un agente que posea actividad interfacial, que permita disminuir la tensión interfacial y las interacciones atractivas entre las gotitas que se encuentran dispersas. Estos agentes que son denominados tensoactivos o surfactantes son especies químicas anfipáticas, que por diversos mecanismos impiden el colapso de las gotitas, evitando su coalescencia o floculación. Se ha propuesto como metodología alternativa económica y efectiva la utilización de doble emulsiones para la extracción y separación de especies químicas que presenten interés. En una emulsión del tipo w/o/w dos fases acuosas están separadas por la fase orgánica inmiscible (fase membrana). Si se agrega un extractante de metales a la fase membrana es posible transferir iones metálicos entre ambas fases acuosas y utilizar el sistema de doble emulsión para la transferencia controlada de especies metálicas. La aplicación de la metodología de doble emulsiones para la separación de iones metálicos requiere de la obtención de un sistema estable, donde no se produzca ruptura o hinchamiento de la emulsión primaria. Es decir, se requiere que el volumen de la emulsión primaria al inicio y al final permanezca invariable, en términos prácticos. En esta memoria de título, se estudió el comportamiento de estabilidad de las emulsiones dobles del tipo w/o/w utilizando el tensoactivo SPAN 80 como agente estabilizador, con la finalidad de aplicarlas como método para separar y concentrar iones metálicos lantánidos, específicamente los iones trivalentes de La, Ce, Pr y Nd. En este estudio se evaluó la influencia de las siguientes variables en la estabilidad de la emulsión doble: las concentraciones de diferentes especies complejantes en la fase acuosa de alimentación, del Cyanex 272 y de los co-extractantes TOPO y TBP en la fase membrana y de ácido clorhídrico en la fase acuosa interna. En todos los casos se trató de determinar la concentración precisa de SPAN 80 capaz de generar una emulsión estable. Debido a que todos los experimentos realizados en esta memoria de título fueron realizados en las mismas condiciones hidrodinámicas de velocidad y tiempo de agitación, manteniendo constante la temperatura, fue posible suponer que siempre se debió obtener el mismo tamaño de glóbulo y una misma área interfacial. Por lo tanto, se pudo considerar un modelo que representa la estabilidad del sistema en términos de la energía libre de Gibbs, considerando dos etapas: la formación de la emulsión propiamente tal y la reacción química interfacial. Teniendo en cuenta estos efectos, referidos a que no es deseable una ruptura parcial o total o un hinchamiento de la emulsión primaria, debe considerarse la adición de una cantidad muy precisa del agente tensoactivo estabilizador, dado que se requiere un mínimo basal para la estabilidad propia del sistema emulsionado y un adicional para compensar el efecto de la reacción química interfacial. Como resultado de este estudio, se lograron obtener las correlaciones matemáticas que permiten determinar la cantidad necesaria de agente tensoactivo SPAN 80 que debe ser adicionada, en función de las concentraciones utilizadas de las otras especies químicas intervinientes en el proceso de extracción y transferencia de los iones lantánidos
The emulsions are a kind of dispersed phase systems that can be found in abundant way in people's daily life and are commonly employed in the food, pharmaceutical, cosmetic and chemical industries. According to the kind of dispersion, they are classified as water in oil (w/o) or oil in water (o/w) emulsions. It is possible to obtain more complex dispersions with more specific purposes, such as water in oil in water (w/o/w) or oil in water in oil (o/w/o) multiple emulsions that require in first place, the formation of an stable basic emulsion and then, its dispersion in the external phase. These double emulsions generate an active liquid membrane capable of transferring some elements between two miscible phases separated by one inmiscible phase. At dispersing two inmiscible liquid phases that have high attraction forces between their own molecules, a great interfacial area is created which produces an instable thermodynamic system, causing the breakdown of the emulsion in a determinate time. The grade of instability of the system depend on the value of interfacial free energy per area unit, or on the minimum work amount required to create an interfacial area unit, known as interfacial tension. To stabilize the dispersion systems or emulsions is necessary to add an agent with interfacial activity, that allows to reduce the interfacial tension and the attractive interactions between the disperse droplets. These agents, known as tensoactives or surfactants, are amphipatic chemical species that prevent, by different mechanisms, the flocculation or coalescence of the droplets. The use of double emulsions has been purposed as an economic and effective alternative methodology to the extraction and separation of chemical species of interest. In the case of water in oil in water double emulsion, two aqueous phases are separated by an inmiscible organic phase, known as membrane phase. If a metal organic extractant is added to the membrane phase, it is possible to transfer metal ions between both aqueous phases and, moreover to use the double emulsion for the controlled metallic species transfer. The application of double emulsion methodology to the separation of metallic ions requires the obtainment of a stable system where break or swelling of primary emulsion does not happen. In other words, it is required that the volume of emulsion practically be invariable to throughout and the term of the extraction process. In this title thesis, it was studied the stability of double emulsions (w/o/w) using the surfactant compound SPAN 80 as a stabilizer agent, with the purpose of apply the emulsion system as a method to separate and concentrate lanthanide ions, specifically the trivalent ions La, Ce, Pr and Nd. In this study was evaluated the influence of the following variables in the stability of double emulsions: the concentration of different complexant agents in the feed aqueous phase, of the Cyanex 272 and the co-extractan TOPO and TBP in the membrane phase and the hydrochloric acid in the internal aqueous phase. In every cases, it was tried of determine the precise concentration of SPAN 80 capable of generate a stable emulsion. On account of that all the experiments of this degree thesis, it were realized in the same hydrodynamics conditions of velocity and stirring time, keeping constant temperature, it was possible to suppose that always the same globule size may be attained as well as the same interfacial area. Therefore, it can be considered a model that represents the system stability in terms of the Gibbs free energy, considering two stages: the emulsion's formation and the interfacial chemical reaction. Considering these effects, assuming that is not desire a partial or total break or swelling of the primary emulsion, it should be consider add a very precise amount of the stabilizer surfactant agent, because it is required a basal minimum to the own-stability of the emulsified system and an additional quantity to compensate the effect of the interfacial chemical reaction. As result of this study, it was reached to obtain the mathematic correlations that permit to determine the necessary amount of the surfactant agent SPAN 80 that should be added, in function of the used concentration of the other participant chemical species in the extraction and transfer process of the lanthanide ions
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Research on substituted polypyrazolylborate ligands could potentially lead to the development of useful compounds in the material sciences such as catalysis and metal ion extraction. A wide variety of substituents can be introduced to the pyrazole rings that modify the properties and reactivity of the complexes. Synthesis of 4-cyano-3-tolylpyrazole followed by the formation of a corresponding thallium(I) complex could allow one to examine the Tl-N bond length. When compared with other related complexes such as TlBpt-Bu, 4CN and TlBpPh, 4CN, the Tl-N bond length in the synthesized complex will help determine the effect of the new substituent.

碩士
國立台灣工業技術學院
化學工程技術研究所
85
The main purpose of this article is to impregnate acid extractants Cyanex-271 and Cyanex-302 into macroporous resin XAD-2 for the extraction of Zn(II) ion from sulfate solution. Dichloromethane was ussed as diluent, and 2-butoxyethanol as modifier, to prepare Extractant-impregnated resin(EIR).The result found that the distribution ratio increased with increasing the amounts of extractants,modifier,pH value and temperature,but decreased with increasing the initial concentration of metal ions. Thecolume operation experiment fount a breakthrough point under low flowrate operation. In the desorptive experiment, high nitric concentration would accelerate the desorption of metal ions out of the colume.The theoretical analysis used the slope analysis method and LETAGROP-DISTR program,and found two complex products for Cyanex-272,threecomplex products for Cyanex-302. The ratio of products would be variedwith the extractant concentration,pH value and temperature.The reactionswere found to be endothermic.

Dissertação de Mestrado Integrado em Engenharia Química apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
Atualmente políticas ambientais cada vez mais restritivas obrigam ao desenvolvimento de sistemas de remoção de metais pesados cada vez mais eficientes. Os líquidos iónicos (ILs) são uma nova classe de solventes que oferecem oportunidades únicas como alternativas ambientalmente sustentáveis aos processos químicos tradicionais no tratamento de efluentes industriais. O presente trabalho investiga a adsorção de iões de Cr (III) e Cd (II) usando a resina Amberlite XAD-7 impregnada com os líquidos iónicos (ILs) butilmetilimidazólio tetrafluoroborato (Bmim BF4) e butilmetilimidazólio hexafluorofosfato (Bmim PF6), bem como com a mistura dos ILs + agente extratante comercial (Cyanex 272). Foi estudada a influência de vários parâmetros operatórios (pH, quantidade de resina, concentração inicial dos metais, tempo de contato e temperatura) que influenciam a capacidade de adsorção da resina XAD-4 com o IL e a resina XAD-4 com IL+ Cyanex 272, na remoção de iões de crómio e cádmio em soluções aquosas. A impregnação dos ILs e do Cyanex na resina Amberlite XAD-4 foi confirmada qualitativamente pelas técnicas de FTIR e microscopia eletrónica de varrimento (SEM). No estudo da resina impregnada com IL Bmim BF4 + Cyanex 272 verificou-se ser a mais eficiente na extração de crómio, a pH 5. Na extração de cádmio foi estudado principalmente o IL Bmim BF4, pois apresenta melhores eficiências de extração que o IL Bmim PF6. Os resultados mostraram que o equilíbrio de adsorção no sistemas Cd (II)/Amberlite XAD-4 Bmim BF4 foi atingido entre 40 e 60 min. O modelo cinético de pseudo segunda ordem é o que descreve melhor a cinética de adsorção. As isotérmicas de adsorção de Langmuir mostram que a capacidade máxima de adsorção para o sistema Cr (III)/Amberlite XAD-4 Bmim BF4 + Cyanex foi de 8.8 mg/g a 50°C; para o sistema Cd (II)/Amberlite XAD-4 Bmim BF4 foi de 28.3 mg/g a 25°C; e para o sistema Cd (II)/Amberlite XAD-4 Bmim BF4 + Cyanex foi de 44 mg/g a 25°C. Estudos termodinâmicos permitiram concluir que a adsorção de crómio pela resina impregnada é de natureza endotérmica, já a adsorção de cádmio é de natureza exotérmica.
Currently increasingly restrictive environmental policies require the development of more effective systems for the removal of heavy metals from aqueous solutions. Ionic liquids (ILs) are a new class of solvents that offers unique opportunities as environmentally friendly alternatives to traditional chemical processes in the treatment of industrial effluents. The present study investigates the adsorption of Cr (III) and Cd (II) ions into a synthetic resin (Amberlite XAD-7) impregnated with a butyl-methylimidazolium tetrafluoroborate ionic liquid (Bmim BF4) or a butyl methylimidazolium hexafluorophosphate ionic liquid (Bmim PF6), as well with the mixture of commercial ILs and extractant agent (Cyanex 272). The influence of various operating parameters (pH, amount of resin, initial concentrations of the metals, contact time and temperature) on the adsorption capacity of XAD-4 resin IL and XAD-4 resin IL + Cyanex 272 towards to removal of chromium and cadmium ions from aqueous solutions was investigated. The impregnation of ILs and Cyanex on Amberlite XAD-4 resin was confirmed qualitatively by FTIR and scanning electron microscope (SEM) techniques. In the study concerning to resin impregnated with IL Bmim + BF4 with Cyanex 272, it was found to be the most effective in chromium extraction at pH 5. The cadmium extraction was studied mostly with IL Bmim BF4, since it presents better extraction efficiencies than IL Bmim PF6. The results showed that the adsorption equilibrium for the system Cd (II) / Amberlite XAD-4 Bmim BF4 was reached between 40 and 60 min. Moreover, it was observed that the pseudo second order kinetic model is one that better describes the adsorption kinetics. The Langmuir adsorption isotherm enabled to get maximum adsorption capacities corresponding to 8.8, 28.3 and 44 mg/g for the systems Cr (III)/Amberlite XAD-4 Bmim BF4 + Cyanex (at 50 °C), Cd (II)/Amberlite XAD-4 Bmim BF4 (at 25 °C) and Cd (II)/Amberlite XAD-4 Bmim BF4 + Cyanex (at 25 °C). Thermodynamic studies have concluded that the chromium adsorption with the impregnated resin is endothermic process, but the adsorption of cadmium presents an exothermic nature.

The extraction of zinc(II) from zinc-plating wastewater by liquid-liquid extraction was studied using the commercial extractants di-(2-ethylhexyl)phosphoric acid (D2EHPA) and bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex® 272), as well as the ionic liquids, Trihexyltetradecylphosphonium bromide (Cyphos® 102), Trihexyltetradecylphosphonium decanoate (Cyphos® 103) and Trihexyltetradecylphosphonium bis(2,4,4- trimethylpentyl)phosphinate (Cyphos® 104), diluted in organic solvents. First, the commercial extractants and the ionic liquids with the most potential were selected based on the results from diluents, modifiers and stripping solution screening tests. Then, the optimization of extraction and re-extraction (stripping) conditions for each extractant was achieved either by effluent pretreatment (pH adjustment) to remove iron prior to liquid-liquid extraction or by adjusting the extractant-to-zinc ratio. Afterwards, one commercial extractant and one ionic liquid were selected for further evaluation based on the following parameters: reusability, contact time (kinetic studies), and loading capacity. Of the two commercial extractants, the most promising results were obtained with 20% (w/w) D2EHPA in kerosene and 3% (v/v) TBP (tributyl phosphate) as the modifier after a contact time of only five minutes. The extraction efficiency for zinc was 98%, with coextraction of iron which can be resolved by pre-treating the effluent to pH 5.5 to precipitate iron prior to liquid-liquid extraction. Selective stripping of zinc from the loaded organic phase was achieved using 0.6 M H2SO4. Under these optimized conditions, the reusability of the organic phase was successfully tested in three cycles of zinc extraction and re-extraction without loss of efficiency. Regarding ionic liquids, 0.08 M Cyphos® 102 in kerosene exhibited superior selectivity for zinc extraction (83%), with little to no co-extraction of iron. Despite this high efficiency, an issue of insolubility of Cyphos® 102 in the diluent was observed, with the ionic liquid being in a layer below kerosene. This insolubility issue made decantation difficult, which affected the reusability of the extraction system. However, the issue can be solved with the addition of 3% (v/v) decanol as modifier, but resulting in the decrease in zinc extraction efficiency to 40%. A raise of the concentration to 0.24 M Cyphos® 102 in kerosene with 3% (v/v) decanol allowed a 95% extraction efficiency of zinc with no insolubility being observed. On the other hand, the stripping of zinc from this loaded organic phase was obtained using a high concentration of HNO3 of 2M. Nevertheless, the problem of reusability of the organic phase remained, whereby zinc extraction decreased to 54% and re-extraction decreased to 5% in the second cycle. Therefore, time and effort need to be devoted to future studies to evaluate the application of Cyphos®102 in liquid-liquid extraction of zinc from zinc-plating wastewaters.
A extração de zinco (II) de água residual da indústria de zincagem por extração líquidolíquido foi estudada utilizando-se os extratantes comerciais Ácido di- (2-etilhexil) fosfórico (D2EHPA) e Ácido bis (2,4,4-trimetilpentil) fosfínico (Cyanex® 272), e também os líquidos iónicos Brometo de triexiltridecilfosfónio (Cyphos® 102), Decanoato de triexiltriltecodecilfosfónio (Cyphos® 103) e Bis (2,4,4-trimetilpentil) fosfinato de trihexiltetradecilfosfónio (Cyphos® 104), diluídos em solventes orgânicos. Primeiro selecionaram-se o extratante e o líquido iónico com mais potencial numa triagem de diluentes e modificadores e em seguida fez-se uma otimização das condições de extração e re-extração de zinco, assim como um estudo de pré-tratamento por ajuste de pH para remoção prévia do ferro. Depois avaliou-se o potencial de cada um dos escolhidos através de estudos de reutilização do extratante em ciclos sucessivos de extração e re-extração, estudos de cinética para conhecimento do tempo de contacto necessário para extração e estudos de capacidade de carga da fase orgânica extratante. Dos dois extratantes comerciais testados, os resultados mais promissores foram obtidos com 20% (p/p) D2EHPA em querosene com 3% (v/v) tributil fosfato (TBP) como modificador, após um tempo de contato de apenas cinco minutos. A eficiência de extração de zinco foi de 98%, mas com co-extração de ferro. No entanto isto pode ser resolvido por pré-tratamento do efluente ajustando o pH a 5.5 para precipitar o ferro antes da extração líquido-líquido. A reextração seletiva de zinco da fase orgânica carregada foi obtida usando 0,6 M de H2SO4. Nestas condições otimizadas a reutilização da fase orgânica foi testada com sucesso em três ciclos de extração e re-extração de zinco sem perda de eficiência. Em relação aos líquidos iônicos, 0.08 M Cyphos® 102 em querosene exibiu seletividade superior em relação à extração de zinco (83%), com pouca ou nenhuma co-extração de ferro. Apesar desta eficiência elevada observou-se um problema de insolubilidade, ficando este líquido iónico numa camada inferior à querosene, o que dificultou a separação da fase orgânica e afetou a sua reutilização. Este problema de insolubilidade foi resolvido com adição de 3% (v/v) decanol como modificador, no entanto a eficiência de extração de zinco diminuiu para 40%. Um aumento da concentração para 0.24 M de Cyphos® 102 em querosene com 3% (v/v) decanol permitiu uma eficiência de 95% de extração de zinco sem o problema da insolubilidade. Por outro lado, a re-extração de zinco desta fase orgânica carregada foi obtida usando 2 M de HNO3. Ainda assim, manteve-se o problema da reutilização da fase orgânica: num segundo ciclo a extração de zinco baixou para 54% e a sua re-extração baixou para 5%. Portanto, serão necessários tempo e esforço dedicados a estudos futuros para avaliar a aplicação de Cyphos®102 na extração líquido-líquido de zinco de águas da indústria de zincagem.
This study was performed in the framework of project METALCHEMBIO (no. 29251) financed by national funds through the FCT – Foundation for Science and Technology and cofinanced by the Algarve´s Regional Operational Program (CRESC Algarve 2020), through Portugal 2020 and European Regional Development Fund (FEDER).

碩士
東海大學
化學系
103
In this thesis, we focus to design and synthesis of two series of lanthanide coordination compounds through in-situ hydrolyzation of cyano groups of 2,2’-bipyridine.We compared theses serious of new coordination polymers according to structures two parts. In the first part, the five one-dimensional Ln(III) coordination polymers, [Ln(bpca)2(CH3COO)]n (Ln = Dy(1), Ho(2), Er(3), Yb(4), Lu(5)) were synthesized in the presence of OAc- anion. Single-crystal X-ray diffraction analyses reveals that compounds 1-5 are isostructural, crustallize in monoclinic, the achiral P21/c space group and asymmetry units linked by acetate groups to form a one-dimensional zigzag chain. In the second part, the four compounds [Ln2(bpdc)2(H2O)3]•nH2O (Ln = Gd(6), Tb(7), Dy(8), Lu(9); n = 3(6-9)) were synthesized from the reactions of Ln(III) in H2O under hydrothermal conditions. Single-crystal X-ray diffraction analyses reveals that compounds 6-9 are isostructural crustallize in monoclinic, the achiral P21/c space group and asymmetry units linked by carboxylate group to form a binuclear complex. All of compounds1-9 are characterized by the single crystal X-ray diffraction (XRD), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), elemental analysis (EA), magnetic susceptibility.

碩士
東海大學
化學系
102
This work contains two parts： (1)Synthesis of compounds 1–3 through in situ [2+ 3] cycloaddition reaction under hydrothermal conditions. Treatment of sdium azide, 6-cyano-2,2’-bipyridyl with Co(ClO4)2•6H2O, Ni(ClO4)2•6H2O and Mn(ClO4)2•6H2O through in situ [2+3] cycloaddition reaction under hydrothermal conditions led to the formation of compounds [M2(N3)2(bptz)2]n (M = Co (1), Ni (2) and Mn (3)), respectively. Compounds 1–3 are 2D layer structures, which 1 and 2 are isostructure, linked by the mixed (µ1,1-azido)(µ-N2,N4-tetrazole) double bridges. In compounds 1 and 2, the intralayer π–π stacking interactions are observed and that the layers are stacked on each other in ···AAA··· fashion. Compound 3 is linked by the mixed (µ1,1-azido)(µ-N2,N5-tetrazole) double bridges. There is no obvious intralayer interaction, where the layers are stacked on each other in ···ABAB··· fashion. The magnetic measurements reveal that compounds 1 and 2 show over all antiferromagnetic behaivor between the metal ions through the µ1,1-azido and μ-N2,N4-tetrazole bridge in high temperature, and are different from magnetic behavior in low temperature. Compound 1 shows the coexistence of spin-canting, metamagnetism and coercivity, 2 shows the coexistence of spin-canting, spin-flop and coercivity, and compound 3 shows the existence of a weak ferromangetic coupling between the metal ions. (2)Synthesis of compounds 4–6 through in situ hydrolysis reaction under hydrothermal conditions. Treatment of 6-cyano-2,2’-bipyridyl with Co(ClO4)2•6H2O, Ni(ClO4)2•6H2O and Mn(ClO4)2•6H2O through in situ hydrolysis reaction under hydrothermal conditions led to the formation of compounds [M3(bpca)4(H2O)4](ClO4)2•2H2O (M = Co (4), Ni (5) and Mn (6)), respectively. Compounds 4–6 are trinuclear structures, in which metal ions linked through syn-anti carboxylate bridges, and that the intramolecules coexistence of hydrogen bonds and π–π stacking interactions. The magnetic measurement reveals that compounds 4–6 show weak antiferromagnetic coupling between the metal ions through the syn-anti carboxylate bridge.

碩士
國立臺灣科技大學
化學工程系
108
In this work, Isoindigo is excellent in electron-deficient properties and coplanarity, is selected as an electron-acceptor unit, and a cyano-substituted trans-1,2-dithiophenylethene and 2,2'-bisthiophene. The thiophene derivative is synthesized as an electron-donor type, which is P2TIV, P2TINV, P2TI2NV, P2TIVN, P2TIH and P2TIN, respectively. A series of properties were identified for the six polymer materials, including thermal properties, absorption wavelengths including solvatochromism, molecular energy levels, material absorption light LE (local excitation) and CT (charge transfer) characteristics of DFT theoretical calculations, thin film polymer alignment, etc., to evaluate applications in polymer solar cells. Since the LUMO offset between these six polymers and PC61BM is insufficient (≤ 0.06 eV), and the conditions for component fabrication are not good, the efficiency of the solar cell is only 3.45% (P2TIV) or 2.92% (P2TIH).