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João G. Crespo

Bio: João G. Crespo is an academic researcher from Universidade Nova de Lisboa. The author has contributed to research in topics: Membrane & Ionic liquid. The author has an hindex of 48, co-authored 311 publications receiving 8673 citations. Previous affiliations of João G. Crespo include University of Lisbon & Fritz Haber Institute of the Max Planck Society.


Papers
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Journal ArticleDOI
TL;DR: State-of-the-art remediation technologies available for reducing dioxins formation and emission from the important sources such as, flue gas, fly ash and soil were described in detail.

401 citations

Journal ArticleDOI
TL;DR: In this paper, room temperature ionic liquid membranes (SILMs) were used for CO 2 /N 2 and CO 2/CH 4 gas separations, and the results showed that the SILMs prepared with the most hydrophobic support are more stable than those based on the hydrophilic support.

230 citations

Journal ArticleDOI
TL;DR: In this article, the authors evaluated the use of room temperature ionic liquids (RTILs), based upon the 1-n-alkyl-3-methylimidazolium cation, in supported liquid membranes (SLMs).

225 citations

Journal ArticleDOI
TL;DR: The features of the solid-liquid phase transition were analyzed, namely the glass transition temperature and the heat capacity jump associated with the transition from the non-equilibrium glass to the metastable supercooled liquid.
Abstract: More than 50 ionic liquids were prepared by using imidazolium, quaternary ammonium, and guanidinium cations and various anions. In these series, different cationic structures such as 1-benzyl-3-methylimidazolium [Bzmim]+, 1,3-dibenzylimidazolium [BzmiBz]+, 1-octyl-3-methylimidazolium [C8mim]+, 1-decyl-3-methylimidazolium [C10mim]+, tricapryl-methylammonium [Aliquat]+, benzyltriethylammonium [BzTEA]+, phenyltrimethylammonium [PhTMA]+, and dimethyldihexylguanidinium [DMG]+ were combined with anions, p-toluenesulfonate [TSA](-), dicyanoamide [DCA]-, saccharine (2-sulfobenzoic acid imide sodium salt) [SAC]-, trifluoroacetate [TFA]-, bis(trifluoromethanesulfonyl)imide [Tf2N]-, trifluoromethanesulfonate [TfO]-, and thiocyanate [SCN]-. Important physical data for these ionic liquids are collated, namely solubility in common solvents, viscosity, density, melting point and water content. Apart from the viscosity, the Newtonian and non-Newtonian behavior of these ionic liquids is also disclosed. Stability of these ionic liquids under thermal, basic, acidic, nucleophilic, and oxidative conditions was also studied. The features of the solid-liquid phase transition were analyzed, namely the glass transition temperature and the heat capacity jump associated with the transition from the non-equilibrium glass to the metastable supercooled liquid. A degradation temperature of each ionic liquid was also determined. Comparisons of the properties of various ionic liquids were made.

215 citations

Journal ArticleDOI
TL;DR: The potential for continuous separation of organic compounds based on the selective transport through supported liquid membranes that contain RTILs is shown, mainly because of the nonvolatile character ofRTILs and their solubility in the surrounding phases.
Abstract: The selective separation of organic compounds is a critical issue in the chemical industry. In case of readily crystallized molecules, selective crystallization is the most practical method for selective separation, whereas for solutes that are liquid at room temperature, separation by fractional distillation, solvent extraction, or chromatographic methods are more convenient. Some of the above-mentioned methods are technically demanding, involve considerable energy costs, and/or result in large amounts of waste solvents. Membranes, defined as permeable and selective barriers between two phases, have been successfully applied in a large diversity of separation processes, including bioseparations, in which classical separation methods are less convenient, undesirable or even not applicable. The reason for the successful use of membrane-based separation processes stems from the fact that these processes have a high energy efficiency, can be used under moderate temperature and pressure conditions, do not require any additional separating agents or adjuvants, and therefore they are regarded as environmentally friendly.[1] Solute extraction and recovery by using supported liquid membranes is recognized as one of the most promising membrane-based processes. In a supported liquid-membrane system, a defined solvent or solvent/carrier solution is immobilized inside the porous structure of a polymeric or ceramic membrane, which separates the feed phase (in which the solutes of interest are solubilized) from the receiving phase (in which these solutes will be transferred and, eventually, concentrated). This configuration has attracted a great deal of interest because the amount of solvent/carrier needed is minimal, the solvent/carrier is continuously regenerated as a result of solute transport to the receiving phase, and loss of the solvent/carrier phase is negligible if an appropriate supported liquid membrane is designed.[2] The use of a room-temperature ionic liquid (RTIL) as an immobilized phase in the supporting membrane between two organic phases in the feed and the receiving compartments is particularly interesting owing to the nonvolatile character of RTILs and their solubility in the surrounding phases, which allows very stable supported liquid membranes to be obtained without any observable loss of the RTIL to the atmosphere or the contacting phases. Herein we show the potential for continuous separation of organic compounds based on the selective transport through supported liquid membranes that contain RTILs. RTILs that involve a 1,3-dialkylimidazolium cation are attracting increasing interest as new media, mainly because of the advantage of being nonvolatile. Depending on the anion and on the alkyl group of the imidazolium cation, the RTIL can solubilize supercritical CO2 (scCO2), a large range of polar and nonpolar organic compounds, and also transitionmetal complexes. Simultaneously, they have low miscibility with water, alkanes, and dialkyl ethers[3] and are insoluble in scCO2. As a result of these properties, they are emerging as an alternative recyclable, environmentally benign, reaction medium for chemical transformations, including transitionmetal catalysis[3] and biocatalysis.[3f, 5] Their use has also been successfully extended as a potential stationary phase for gas chromatography,[6] in pervaporation,[7] and for the substitution of traditional organic solvents (OS) in aqueous ±OS[7a, 8] and OS± scCO2 biphasic extractions.[4, 9] It is assumed that the 1,3dialkylimidazolium RTIL are not a statistical aggregate of anions and cations, but instead a more organized structure that contains polar and nonpolar regions as a result of the formation of weak interactions, mainly as hydrogen bonds, with 2-H of the imidazolium ring.[10] The above information prompted us to study the potential of using RTIL in supported liquid membranes for selective separation processes. To illustrate the concept, and as a result of transport studies with representative organic functional compounds, we used a mixture of the organic isomeric amines hexylamine, diisopropylamine, and triethylamine (1:1:1 molar ratio) in diethyl ether in side A of the cell (Figure 1). The two sides of the cell were separated by the RTIL 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) immobilized in the por[5] [Pt2(nBuCS2)4] and [Pt2(nBuCS2)4I2] were prepared by the similar procedures with literature methods using toluene and n-hexane.[4] [6] P. M. Chaikin, R. L. Greene, S. Etemad, E. Engler, Phys. Rev. B 1976, 13, 1627 ± 1632. [7] S. A. Borshch, K. Prassides, V. Robert, A. O. Solonenko, J. Chem. Phys. 1998, 109, 4562 ± 4568. [8] H. Tanaka, K. Marumoto, S. Kuroda, M. Mitsumi, K. Toriumi, unpublished results. [9] O. Kahn, Molecular Magnetism, VCH, New York, 1993, pp. 251 ± 286. [10] Field dependence of M of 1 was also measured near the phasetransition temperature under the magnetic field of H 1 ± 5 T. No variation was observed up to 5 T. [11] a) A. Altomare, G. Cascarano, C. Giacovazzo, A. Guagliardi, M. C. Burla, G. Polidori, M. Camalli, J. Appl. Crystallogr. 1994, 27, 435 (SIR92); b) G. M. Sheldrick, SHELXL-97, University of Gˆttingen, Gˆttingen (Germany), 1997; c) Crystal Structure Analysis Package, Molecular Structure Corporation, 1985, 1999 ; d) A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C. Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori, R. Spagna, J. Appl. Crystallogr. 1999, 32, 115 ± 119 (SIR97). [12] Z. Otwinowski, W. Minor, Methods Enzymol. 1997, 276, 307 ± 326.

213 citations


Cited by
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Journal ArticleDOI
01 Apr 1988-Nature
TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

9,929 citations

Journal ArticleDOI
TL;DR: Strong acids and bases seem to be the best desorbing agents to produce arsenic concentrates, and some commercial adsorbents which include resins, gels, silica, treated silica tested for arsenic removal come out to be superior.

3,168 citations

01 Jan 2016
TL;DR: The principles of fluorescence spectroscopy is universally compatible with any devices to read and is available in the digital library an online access to it is set as public so you can download it instantly.
Abstract: Thank you very much for downloading principles of fluorescence spectroscopy. As you may know, people have look hundreds times for their favorite novels like this principles of fluorescence spectroscopy, but end up in malicious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they cope with some harmful bugs inside their desktop computer. principles of fluorescence spectroscopy is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library spans in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the principles of fluorescence spectroscopy is universally compatible with any devices to read.

2,960 citations

Journal ArticleDOI
TL;DR: The concepts of design and the scientific philosophy of Green Chemistry are covered with a set of illustrative examples and the challenge of using the Principles as a cohesive design system is discussed.
Abstract: Green Chemistry is a relatively new emerging field that strives to work at the molecular level to achieve sustainability. The field has received widespread interest in the past decade due to its ability to harness chemical innovation to meet environmental and economic goals simultaneously. Green Chemistry has a framework of a cohesive set of Twelve Principles, which have been systematically surveyed in this critical review. This article covers the concepts of design and the scientific philosophy of Green Chemistry with a set of illustrative examples. Future trends in Green Chemistry are discussed with the challenge of using the Principles as a cohesive design system (93 references).

2,942 citations

Journal ArticleDOI
TL;DR: This paper presents a meta-analysis of four-Wave Mixing and its applications in nanofiltration, which shows clear trends in high-performance liquid chromatography and also investigates the role of nano-magnifying lens technology in this process.
Abstract: 12.2.2. Four-Wave Mixing (FWM) 4849 12.2.3. Dye Aggregation 4850 12.2.4. Optoelectronic Nanodevices 4850 12.3. Sensor 4851 12.3.1. Chemical Sensor 4851 12.3.2. Biological Sensor 4851 12.4. Catalysis 4852 13. Conclusion and Perspectives 4852 14. Abbreviations 4853 15. Acknowledgements 4854 16. References 4854 * Corresponding author E-mail: tpal@chem.iitkgp.ernet.in. † Raidighi College. § Indian Institute of Technology. 4797 Chem. Rev. 2007, 107, 4797−4862

2,414 citations