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1.
J Am Chem Soc ; 144(51): 23321-23331, 2022 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-36516341

RESUMEN

Catalytic ammoxidation of alcohols into nitriles is an essential reaction in organic synthesis. While highly desirable, conducting the synthesis at room temperature is challenging, using NH3 as the nitrogen source, O2 as the oxidant, and a catalyst without noble metals. Herein, we report robust photocatalysts consisting of Fe(III)-modified titanium dioxide (Fe/TiO2) for ammoxidation reactions at room temperature utilizing oxygen at atmospheric pressure, NH3 as the nitrogen source, and NH4Br as an additive. To the best of our knowledge, this is the first example of catalytic ammoxidation of alcohols over a photocatalyst using such cheap and benign materials. Various (hetero) aromatic nitriles were synthesized at high yields, and aliphatic alcohols could also be transformed into corresponding nitriles at considerable yields. The modification of TiO2 with Fe(III) facilitates the formation of active •O2- radicals and increases the adsorption of NH3 and amino intermediates on the catalyst, accelerating the ammoxidation to yield nitriles. The additive NH4Br impressively improves the catalytic efficiency via the formation of bromine radicals (Br•) from Br-, which works synergistically with •O2- to capture H• from Cα-H, which is present in benzyl alcohol and the intermediate aldimine (RCH═NH), to generate the active carbon-centered radicals. Further, the generation of Br• from the Br- additive consumes the photogenerated holes and OH• radicals to prevent over-oxidation, significantly improving the selectivity toward nitriles. This amalgamation of function and synergy of the Fe(III)-doped TiO2 and NH4Br reveals new opportunities for developing semiconductor-based photocatalytic systems for fine chemical synthesis.

2.
Environ Monit Assess ; 187(5): 306, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25925159

RESUMEN

Heavy metal pollution of sediments is a growing concern in most parts of the world, and numerous studies focussed on identifying contaminated sediments by using a range of digestion methods and pollution indices to estimate sediment contamination have been described in the literature. The current work provides a critical review of the more commonly used sediment digestion methods and identifies that weak acid digestion is more likely to provide guidance on elements that are likely to be bioavailable than other traditional methods of digestion. This work also reviews common pollution indices and identifies the Nemerow Pollution Index as the most appropriate method for establishing overall sediment quality. Consequently, a modified Pollution Index that can lead to a more reliable understanding of whole sediment quality is proposed. This modified pollution index is then tested against a number of existing studies and demonstrated to give a reliable and rapid estimate of sediment contamination and quality.


Asunto(s)
Monitoreo del Ambiente/métodos , Estuarios , Sedimentos Geológicos/química , Metales Pesados/análisis , Contaminantes Químicos del Agua/análisis , Monitoreo del Ambiente/normas , Metales Pesados/normas , Agua de Mar/química , Contaminantes Químicos del Agua/normas
3.
Nanoscale ; 16(21): 10168-10207, 2024 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-38722105

RESUMEN

Artificial switchable catalysis is a new, rapidly expanding field that offers great potential advantages for both homogeneous and heterogeneous catalytic systems. Light irradiation is widely accepted as the best stimulus to artificial switchable chemical systems. In recent years, tremendous progress has been made in the synthesis and application of photo-switchable catalysts that can control when and where bond formation and dissociation take place in reactant molecules. Photo-switchable catalysis is a niche area in current catalysis, on which systematic analysis and reviews are still lacking in the scientific literature, yet it offers many intriguing and versatile applications, particularly in organic synthesis. This review aims to highlight the recent advances in photo-switchable catalyst systems that can result in two different chemical product outcomes and thus achieve a degree of control over organic synthetic reactions. Furthermore, this review evaluates different approaches that have been employed to achieve dynamic control over both the catalytic function and the selectivity of several different types of synthesis reactions, along with the remaining challenges and potential opportunities. Owing to the great diversity of the types of reactions and conditions adopted, a quantitative comparison of efficiencies between considered systems is not the focus of this review, instead the review showcases how insights from successful adopted strategies can help better harness and channel the power of photoswitchability in this new and promising area of catalysis research.

4.
Water Res ; 43(5): 1323-9, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19157487

RESUMEN

The presence of selenite or selenate in potable water is a health hazard especially when consumed over a long period of time. Its removal from potable water is of importance. This paper reports technology for the removal of selenite from water through the use of thermally activated layered double hydroxides. Mg/Al hydrotalcites with selenite in the interlayer were prepared at different times from 0.5 to 20 h through ion exchange. X-ray diffraction of the MgAlSeO3 hydrotalcites indicates that the selenite anion entered the interlayer spacing of Mg/Al hydrotalcite and MgAlSeO3 hydrotalcite was formed. Raman spectra proved the presence of selenite anion in the hydrotalcite interlayer as the counter anion. The band intensity and width of MgAlSeO3 hydrotalcite in the region of 3800-3000 cm(-1) increase with the adsorption of selenite by the Mg/Al hydrotalcite. The characteristic bands of free selenite anions in the MgAlSeO3 hydrotalcites are located between the region between 850 and 800 cm(-1). The Raman spectra of the lower wave number region of 550-500 cm(-1) show a shift toward higher wave numbers with adsorption of the selenite. An estimation of the amount of selenite anion removed by the thermally activated layered double hydroxide was obtained through the measurement of the intensity of the selenite Raman bands at 814 and 835 cm(-1) resulting from the amount of selenite anion remaining in solution. Thermally activated LDHs provide a mechanism for removing selenite anions from aqueous solutions.


Asunto(s)
Aniones/aislamiento & purificación , Hidróxidos/química , Selenito de Sodio/aislamiento & purificación , Temperatura , Absorción , Aluminio/química , Hidróxido de Aluminio/química , Magnesio/química , Hidróxido de Magnesio/química , Soluciones , Espectrometría Raman , Factores de Tiempo , Difracción de Rayos X
5.
Artículo en Inglés | MEDLINE | ID: mdl-18054839

RESUMEN

Infrared emission and infrared spectroscopy has been used to study a series of selected natural smithsonites from different origins. An intense broad infrared band at 1440 cm(-1) is assigned to the nu3 CO3(2-) antisymmetric stretching vibration. An additional band is resolved at 1335 cm(-1). An intense sharp Raman band at 1092 cm(-1) is assigned to the CO3(2-) symmetric stretching vibration. Infrared emission spectra show a broad antisymmetric band at 1442 cm(-1) shifting to lower wavenumbers with thermal treatment. A band observed at 870 cm(-1) with a band of lesser intensity at 842 cm(-1) shifts to higher wavenumbers upon thermal treatment and is observed at 865 cm(-1) at 400 degrees C and is assigned to the CO3(2-)nu2 mode. No nu2 bending modes are observed in the Raman spectra for smithsonite. The band at 746 cm(-1) shifts to 743 cm(-1) at 400 degrees C and is attributed to the CO3(2-)nu4 in phase bending modes. Two infrared bands at 744 and around 729 cm(-1) are assigned to the nu4 in phase bending mode. Multiple bands may be attributed to the structural distortion ZnO6 octahedron. This structural distortion is brought about by the substitution of Zn by some other cation. A number of bands at 2499, 2597, 2858, 2954 and 2991 cm(-1) in both the IE and infrared spectra are attributed to combination bands.


Asunto(s)
Carbonatos/química , Minerales/química , Compuestos de Zinc/química , Espectrofotometría Infrarroja
6.
Artículo en Inglés | MEDLINE | ID: mdl-16814602

RESUMEN

The mineral giniite has been synthesised and characterised by XRD, SEM and Raman and infrared spectroscopy. SEM images of the olive-green giniite display a very unusual image of pseudo-spheres with roughened surfaces of around 1-10microm in size. The face to face contact of the spheres suggests that the spheres are colloidal and carry a surface charge. Raman spectroscopy proves the (PO4)3- units are reduced in symmetry and in all probability more than one type of phosphate unit is found in the structure. Raman bands at 77K are observed at 3380 and 3186cm-1 with an additional sharp band at 3100cm-1. The first two bands are assigned to water stretching vibrations and the latter to an OH stretching band. Intense Raman bands observed at 396, 346 and 234cm-1are attributed to the FeO stretching vibrations. The giniite phosphate units are characterised by two Raman bands at 1023 and 948cm-1 assigned to symmetric stretching mode of the (PO4)3- units. A complex band is observed at 460.5cm-1 with additional components at 486.8 and 445.7cm-1 attributed to the nu(2) bending modes suggesting a reduction of symmetry of the (PO4)3- units.


Asunto(s)
Compuestos Férricos/química , Minerales/química , Fosfatos/química , Espectrometría Raman , Compuestos Férricos/síntesis química , Minerales/síntesis química , Fosfatos/síntesis química
7.
Spectrochim Acta A Mol Biomol Spectrosc ; 66(4-5): 1075-81, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17027326

RESUMEN

The ability of near infrared reflectance spectroscopy to classify the rosasite group minerals from spectral characteristics is demonstrated. NIR spectroscopy can be regarded as an alternative tool for structure analysis. The spectra show that rosasite group minerals with different cations can be distinguished. Ni2+ in nullaginite [Ni2(CO3)(OH)2] is conspicuous through a single broad band absorption feature at 8525 cm-1, extended from 11,000 to 7000 cm-1. The effect of Ni on Cu is seen in the spectrum of glaukosphaerite [(Cu, Ni)2(CO3)(OH)2] both by a red shift of the spectrum and reduction in intensity of bands with variable positions of band maxima for Cu2+ at 6995 cm-1 and Ni2+ at 7865 cm-1. The spectrum of rosasite [(Cu, Zn)2(CO)3(OH)2] is characterised by Cu2+ band at 7535 cm-1. Kolwezite [(Cu, Co)2(CO)3(OH)2] is a spectral mixture of Cu and Co but optically separated by Co2+ and Cu2+ peaks at 8385 and 7520 cm-1. Vibrational spectra of carbonates show a number of bands in the 7000-4000 cm-1 region attributable to overtones, combination of OH stretching and deformation modes. They appear to be uniform in nature since the structure of rosasite group minerals is identical. The complexity of these features varies between samples because of the variation in composition and hence is useful for discriminating different hydrous carbonates.


Asunto(s)
Carbonatos/análisis , Carbonatos/química , Cobre/química , Minerales/química , Espectroscopía Infrarroja Corta , Compuestos de Zinc/química , Microscopía Electrónica de Rastreo
8.
Spectrochim Acta A Mol Biomol Spectrosc ; 66(4-5): 1068-74, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17023200

RESUMEN

Minerals in the rosasite group namely rosasite, glaucosphaerite, kolwezite, mcguinnessite have been studied by a combination of infrared and Raman spectroscopy. The spectral patterns for the minerals rosasite, glaucosphaerite, kolwezite and mcguinnessite are similar to that of malachite implying the molecular structure is similar to malachite. A comparison is made with the spectrum of malachite. The rosasite mineral group is characterised by two OH stretching vibrations at approximately 3401 and 3311 cm-1. Two intense bands observed at approximately 1096 and 1046 cm-1 are assigned to nu1(CO3)2- symmetric stretching vibration and the delta OH deformation mode. Multiple bands are found in the 800-900 and 650-750 cm-1 regions attributed to the nu2 and nu4 bending modes confirming the symmetry reduction of the carbonate anion in the rosasite mineral group as C2v or Cs. A band at approximately 560 cm-1 is assigned to a CuO stretching mode.


Asunto(s)
Carbonatos/química , Cobre/química , Minerales/química , Espectrometría Raman , Vibración , Compuestos de Zinc/química , Radical Hidroxilo/química , Espectroscopía Infrarroja por Transformada de Fourier
9.
J Colloid Interface Sci ; 490: 163-173, 2017 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-27912114

RESUMEN

Application of inorganic-organic clays (IOCs) for the remediation of hexavalent chromium (Cr (VI)) and the effect of bisphenol-A (BPA) were investigated. IOCs were better adsorbents for the removal of Cr (VI) than organoclay. Solution pH significantly affected the surface charge of IOCs and speciation of Cr in the solution; hence, the adsorption of Cr onto IOCs. Pseudo-second order model and Langmuir model were the best fit for the kinetics and equilibrium data, indicating chemisorption and formation of monolayer on homogenous adsorption sites, respectively. Cr (VI) adsorption by IOCs was driven by electrostatic interactions between positively charged IOC surfaces and HCrO4- anions. The IOC adsorption capacity for Cr (VI) correlates with the amount of loosely held ODTMA on the external surface of the clay. Involvement of an anion-exchange reaction was suggested in which the counter halide ions of the cationic surfactants were replaced by HCrO4- anions. Cr (VI) adsorption was not affected by the presence of BPA in the medium and two mechanisms for the adsorption of BPA and Cr (VI) were suggested. Partial reduction of Cr (VI) to Cr (III) was observed on the surface of IOC and the reducing agent responsible was suggested to be the Fe (II) in montmorillonite.

10.
Spectrochim Acta A Mol Biomol Spectrosc ; 63(3): 685-9, 2006 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-16024273

RESUMEN

Raman microscopy has been used to study the molecular structure of a synthetic goudeyite (YCu(6)(AsO(4))(3)(OH)(6) x 3H(2)O). These types of minerals have a porous framework similar to that of zeolites with a structure based upon (A(3+))(1-x)(A(2+))(x)Cu(6)(OH)(6)(AsO(4))(3-x)(AsO(3)OH)(x). Two sets of AsO stretching vibrations were found and assigned to the vibrational modes of AsO(4) and HAsO(4) units. Two Raman bands are observed in the region 885-915 and 867-870 cm(-1) region and are assigned to the AsO stretching vibrations of (HAsO(4))(2-) and (H(2)AsO(4))(-) units. The position of the bands indicates a C(2v) symmetry of the (H(2)AsO(4))(-) anion. Two bands are found at around 800 and 835 cm(-1) and are assigned to the stretching vibrations of uncomplexed (AsO(4))(3-) units. Bands are observed at around 435, 403 and 395 cm(-1) and are assigned to the nu(2) bending modes of the HAsO(4) (434 and 400 cm(-1)) and the AsO(4) groups (324 cm(-1)).


Asunto(s)
Aluminio/química , Cobre/química , Espectrometría Raman/métodos , Itrio/química , Zeolitas/química , Arseniatos/química , Bismuto/química , Hidróxidos/química , Espectrofotometría Infrarroja , Agua/química , Difracción de Rayos X
11.
Spectrochim Acta A Mol Biomol Spectrosc ; 62(1-3): 181-8, 2005 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-16257712

RESUMEN

The phosphate minerals hannayite, newberyite and struvite have been studied by Raman spectroscopy using a thermal stage. Hannayite and newberyite are characterised by an intense band at around 980cm(-1) assigned to the v(1) symmetric stretching vibration of the HPO(4) units. In contrast the symmetric stretching mode is observed at 942cm(-1) for struvite. The Raman spectra are characterised by multiple v(3) anti-symmetric stretching bands and v(2) and v(4) bending modes indicating strong distortion of the HPO(4) and PO(4) units. Hannayite and newberyite are defined by bands at 3382 and 3350cm(-1) attributed to HOPO(3) vibrations and hannayite and struvite by bands at 2990, 2973 and 2874 assigned to NH(4)(+) bands. Raman spectroscopy has proven most useful for the analysis of these 'cave' minerals where complex paragenetic relationships exist between the minerals.


Asunto(s)
Compuestos de Magnesio/química , Fosfatos/química , Ácidos Fosfóricos/química , Espectrometría Raman/métodos , Conformación Molecular , Estruvita , Termodinámica
12.
Mar Pollut Bull ; 91(1): 380-8, 2015 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-25537749

RESUMEN

Sediment samples were taken from six sampling sites in Bramble Bay, Queensland, Australia between February and November in 2012. They were analysed for a range of heavy metals including Al, Fe, Mn, Ti, Ce, Th, U, V, Cr, Co, Ni, Cu, Zn, As, Cd, Sb, Te, Hg, Tl and Pb. Fraction analysis, Enrichment Factors and Principal Component Analysis-Absolute Principal Component Scores (PCA-APCS) were carried out in order to assess metal pollution, potential bioavailability and source apportionment. Cr and Ni exceeded the Australian Interim Sediment Quality Guidelines at some sampling sites, while Hg was found to be the most enriched metal. Fraction analysis identified increased weak acid soluble Hg and Cd during the sampling period. Source apportionment via PCA-APCS found four sources of metals pollution, namely, marine sediments, shipping, antifouling coatings and a mixed source. These sources need to be considered in any metal pollution control measure within Bramble Bay.


Asunto(s)
Bahías/análisis , Monitoreo del Ambiente/métodos , Sedimentos Geológicos/análisis , Metales Pesados/análisis , Contaminantes Químicos del Agua/análisis , Bahías/química , Sedimentos Geológicos/química , Mercurio/análisis , Análisis de Componente Principal , Queensland , Espectrometría de Masas en Tándem
13.
J Colloid Interface Sci ; 247(1): 132-7, 2002 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-16290448

RESUMEN

A model for pseudoboehmite crystallite packing formed during the hydrolysis of trisecbutoxyaluminium is postulated. The model describes platelike crystallites of pseudoboehmite stacked in a sharing edges only configuration. With this type of stacking, the pore sizes detected are approximately equal to the crystallite sizes of the hydrolysates. The hydrolysates age via a dissolution re-precipitation reaction. This increases the size of the crystallite size of the pseudoboehmite formed, speeding peptization by allowing nitrate ions to enter pores and access the surfaces of the crystallites. This type of model also allows an explanation for the peptization kinetics of systems containing sec-butanol formed during the hydrolysis of trisecbutoxyaluminium.

14.
J Colloid Interface Sci ; 251(2): 350-9, 2002 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-16290740

RESUMEN

Controlled rate thermal analysis (CRTA) allows the separation of adsorbed and intercalated hydrazine. CRTA displays the presence of three different types of hydrogen-bonded hydrazine in the intercalation complex: (a) The first is adsorbed loosely bonded on the kaolinite structure fully expanded by hydrazine-hydrate and liberated between approx 50 and 70 degrees C (b) The second intercalated hydrazine is lost between approx 70 and 85 degrees C. (c) The third type of intercalated-hydrazine molecule is lost in the 85-130 degrees C range. CRTA at 70 degrees C enables the removal of hydrazine-water and results in the partial collapse of the hydrazine-intercalated kaolinite structure to form a hydrazine-intercalated kaolinite. Removal of the adsorbed hydrazine enables the DRIFT spectra of the hydrazine-intercalated complex without any adsorbed hydrazine to be obtained. A band at 3626 cm(-1) attributed to the inner surface hydroxyls of kaolinite hydrogen bonded to hydrazine is observed. The intercalation of hydrazine-hydrate into kaolinite is complex and results from the different types of surface interactions of the hydrazine with the kaolinite surfaces.

15.
Spectrochim Acta A Mol Biomol Spectrosc ; 59(10): 2241-6, 2003 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-12909138

RESUMEN

The contamination of soils with heavy metals such as As, Cr and Cu is of great importance; the remediation of such soils even more so. Arsenic compounds are prevalent in soils either through leaching of mine tailings, the use of Cu/Cr/As as a wood preservative or through the use of arsenic in cattle dips. The arsenic compounds in soils and leachates can be highly reactive and mobile, resulting in the formation of metal arsenate compounds. Of these compounds, one such set of minerals that can be formed is the vivianite arsenate minerals. Raman spectroscopy has been used to characterise the vivianite arsenates and to identify arsenic contaminants in a soil.


Asunto(s)
Arseniatos/química , Contaminantes del Suelo , Espectrometría Raman
16.
Mar Pollut Bull ; 81(1): 248-55, 2014 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-24485297

RESUMEN

Sediment samples from 13 sampling sites in Deception Bay, Australia were analysed for the presence of heavy metals. Enrichment factors, modified contamination indices and Nemerow pollution indices were calculated for each sampling site to determine sediment quality. The results indicate significant pollution of most sites by lead (average enrichment factor (EF) of 13), but there is also enrichment of arsenic (average EF 2.3), zinc (average EF 2.7) and other heavy metals. The modified degree of contamination indices (average 1.0) suggests that there is little contamination. By contrast, the Nemerow pollution index (average 5.8) suggests that Deception Bay is heavily contaminated. Cluster analysis was undertaken to identify groups of elements. Strong correlation between some elements and two distinct clusters of sampling sites based on sediment type was evident. These results have implications for pollution in complex marine environments where there is significant influx of sand and sediment into an estuarine environment.


Asunto(s)
Bahías , Monitoreo del Ambiente/métodos , Sedimentos Geológicos/química , Contaminantes Químicos del Agua/química , Metales Pesados/análisis , Queensland
17.
Mar Pollut Bull ; 89(1-2): 464-472, 2014 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-25440195

RESUMEN

Thirteen sites in Deception Bay, Queensland, Australia were sampled three times over a period of 7 months and assessed for contamination by a range of heavy metals, primarily As, Cd, Cr, Cu, Pb and Hg. Fraction analysis, enrichment factors and Principal Components Analysis-Absolute Principal Component Scores (PCA-APCS) analysis were conducted in order to identify the potential bioavailability of these elements of concern and their sources. Hg and Te were identified as the elements of highest enrichment in Deception Bay while marine sediments, shipping and antifouling agents were identified as the sources of the Weak Acid Extractable Metals (WE-M), with antifouling agents showing long residence time for mercury contamination. This has significant implications for the future of monitoring and regulation of heavy metal contamination within Deception Bay.


Asunto(s)
Organismos Acuáticos/metabolismo , Monitoreo del Ambiente , Sedimentos Geológicos/química , Metales Pesados/farmacocinética , Contaminantes Químicos del Agua/farmacocinética , Bahías , Disponibilidad Biológica , Metales Pesados/análisis , Análisis de Componente Principal , Queensland , Estaciones del Año , Contaminantes Químicos del Agua/análisis
18.
J Colloid Interface Sci ; 436: 194-203, 2014 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-25268823

RESUMEN

A series of macro-mesoporous TiO2/Al2O3 nanocomposites with different morphologies were synthesized. The materials were calcined at 723 K and were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscope (TEM), N2 adsorption/desorption, Infrared Emission Spectroscopy (IES), X-ray photoelectron spectroscopy (XPS) and UV-visible spectroscopy (UV-visible). A modified approach was proposed for the synthesis of 1D (fibrous) nanocomposite with higher Ti/Al molar ratio (2:1) at lower temperature (<100°C), which makes it possible to synthesize such materials on industrial scale. The performance-morphology relationship of as-synthesized TiO2/Al2O3 nanocomposites was investigated by the photocatalytic degradation of a model organic pollutant under UV irradiation. The samples with 1D (fibrous) morphology exhibited superior catalytic performance than the samples without, such as titania microspheres.

19.
J Colloid Interface Sci ; 386(1): 66-72, 2012 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-22909968

RESUMEN

Using a series of partial phase transitions, an effective photocatalyst with fibril morphology was prepared. The catalytic activities of these materials were tested against phenol and herbicide in water. Both H-titanate and TiO(2)-(B) fibres decorated with anatase nanocrystals were studied. It was found that anatase coated TiO(2)-(B) fibres prepared by a 45 h hydrothermal treatment followed by calcination were not only superior photocatalysts but could also be readily separated from the slurry after photocatalytic reactions due to its fibril morphology.

20.
J Colloid Interface Sci ; 360(1): 132-8, 2011 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-21570088

RESUMEN

The effective removal of pollutants using a thermally and chemically stable substrate that has controllable absorption properties is a goal of water treatment. In this study, the surfaces of thin alumina (γ-Al(2)O(3)) nanofibres were modified by the grafting either of two organosilane agents, 3-chloro-propyl-triethoxysilane (CPTES) and octyl-triethoxysilane (OTES). These modified materials were then trialed as absorbents for the removal of two herbicides, alachlor and imazaquin from water. The formation of organic groups during the functionalisation process established super hydrophobic sites on the surfaces of the nanofibres. This super hydrophobic group is a kind of protruding adsorption site which facilitates the intimate contact with the pollutants. OTES grafted substrate were shown to be more selective for alachlor while imazaquin selectivity is shown by the CPTES grafted substrate. Kinetics studies revealed that imazaquin was rapidly adsorbed on CPTES-modified surfaces. However, the adsorption of alachlor by OTES grafted surface was achieved more slowly.


Asunto(s)
Acetamidas/química , Óxido de Aluminio/química , Herbicidas/química , Imidazoles/química , Nanofibras/química , Quinolinas/química , Adsorción , Tamaño de la Partícula , Propiedades de Superficie
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