Navegando por Assunto "Esmectita"

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Adsorção de fenol e benzeno em montmorilonita modificada com brometo de hexadeciltrimetilamônio
(2014-12) SANTOS, Sheila Silva dos; LEMOS, Vanda Porpino; VILAÇA, A. L. C.; TAVARES, Laís Conceição; QUEIRÓZ, Leandro Santos
This study evaluates the intercalation of the smectite dioctahedric state of Acre, Brazil, with the quaternary ammonium salt bromide, hexadecyltrimethylammonium (HDTMA) at concentrations ranging from 1 to 5 times the value of the original clay CEC and its application in the adsorption of phenol and benzene in the liquid phase. The materials were characterized by microanalysis X-ray diffraction, scanning electron microscopy /energy dispersive spectroscopy and infrared spectroscopy. The adsorption processes were carried out in simple systems and measurements of the concentrations of phenol and benzene were performed by spectrophotometry in the ultraviolet region. The results indicated that the intercalation of smectite with HDTMA provided approximately 78.8 expansion (range d001: 1.47 nm to 1.91 nm) and sharp decrease of the interlayer positions of elements such as Na, Ca, Mg and K, together by delamination/exfoliation of the clay original. In adsorption processes of phenol and benzene at HDTMA-arg 5 the following results were obtained: qmax = 4.44 and 35.8 mg.g-1; KL= 0.076 and 0.115 L.g-1; ΔGº = -16.85 and -18.38 kJ.mol-1, respectively. These data indicated that the adsorption of benzene and phenol in liquid phase in the organophilic HDTMA-arg 5 were favorable, spontaneous and physical interactions.
Acesso aberto (Open Access)
Adsorção de molibdato em minerais de argila delaminados e amorfizados
(Universidade Federal do Pará, 2012-04-15) PEREIRA, Patricia Magalhães; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
The search for efficient methodologies to control environmental pollution, as well as the development of technologies in the fields chemical, physical and biological have been widely discussed in order to produce efficient alternatives to improve the quality of life and control of chemical pollutants (organic or inorganic) that over the years are being dumped into the environment so as inconsequential by households and industries. Thus, it is important to know about the adsorptive behavior of metals in the soil, because high concentrations of metals produce adverse effects on the environment. Molybdenum is an essential element for biological functions of plants and animals, but in high concentrations in the body can lead to bone deformities, anemia, abnormal liver and lead to death.The possibility of interaction of organic-inorganic compounds (Humic Acid, Urea andH2SO4) in sediments "in nature” from the region of Acre, was investigated with the aim of evaluating the possibility of applying these materials in adsorption processes in molybdate aqueous solutions. The natural samples used in this study have a high content of clay minerals, mainly smectite, kaolinite and low content of primary minerals such as feldspar and quartz. All samples "in nature" were characterized by XRD, XRF, FTIR, SEM and pHH2O and pHKCl. The modification with inorganic acid concentrations (0.25, 0.5, 1 and 1.5mol.L-1), temperature and contact time are important parameters in the process of delamination of the clay minerals. As the use of organic compounds such as urea and humic acid were efficient in the amorphization. The study by XRD in the modified samples show a change in the structure when H2SO4 at the concentrations used, but this fact is only observed for 15Å peak, characteristic of smectite, all other peaks showed no significant change. The synthesis of organic compounds promoted the amorphization of the smectite peak reference. Thus, as the sediment naturally has clay (smectite, kaolinite), confirmed by XRD and the presence of iron, indicating a transition to the montmorillonite nontronite, and with isomorphous substitution of iron is expected to strong interaction between the adsorption molybdate fractions modified with respect to the natural. The introduction of H+ due to the modification process with sulfuric acid promoted the replacement of calcium ions in the structure confirmed by semi-quantitative analysis performed by EDS. SEM analysis indicated the presence in natural samples cluster morphology, this fact was not observed in the modified samples, which was observed delamination and amorphization. The equilibrium conditions in the adsorption process were investigated in which it is inserted, time of 2 h and the solution pH was measured before and after adsorption. The equilibrium datawere represented by theisotherm models Langmuir, Freundlich and Sips. The adsorption process had better performance in the concentrations for samples and S10H15 S10UH. The humic acid modified samples contained higher Qmáx =3.43, values regression fit to the model obtained indicate Freundlich efficient adsorption process, the modified samples effective adsorbed molybdate anion in comparison to natural sample.
Acesso aberto (Open Access)
Aplicação de Al-PILC na adsorção de Cu2+, Ni2+e Co2+ utilizando modelos físico-químicos de adsorção
(2007) GUERRA, Denis de Jesus Lima; AIROLDI, Claudio; LEMOS, Vanda Porpino; ANGÉLICA, Rômulo Simões; VIANA, Rúbia Ribeiro
Smectite sample from the Serra de Maicuru area (Pará state, northern Brazil, Amazon region) were used for the pillaring process with Al13. Aluminum pillared clay (Al-PILC) was characterized by XRD, SEM and EDS. the textural analysis using nitrogen adsorption-desorption isotherms. The aim of this paper is to study in how Al-PILC adsorb heavy metals. The adsorption of Cu2+, Ni2+, Co2+ ions from aqueous solution in room temperature by Al-PILC have been carried out. The Langmuir, Freundlich and Temkin adsorption isotherm models have been applied to fit the experimental data, with the first model well adjusted with r = 0.999. The one-surface Langmuir equation provided the best fit to the data. The Freundlich equation presented limitations in rises concentrations, but acceptable values of parameters were obtained (Kf and n) with the use of the three models. The parameters were used to calculate the amount adsorbed Nf, a function constant Cs.
Acesso aberto (Open Access)
Cristaloquímica de esmectitas dioctaédricas em bentonitas brasileiras
(Universidade Federal do Pará, 2025-07-01) VEGA PORRAS, David Enrique; PAZ, Simone Patrícia Aranha da; http://lattes.cnpq.br/5376678084716817; https://orcid.org/0000-0002-5880-7638
Bentonites are mineral inputs of great industrial interest due to the physicochemical properties of clay minerals from the smectite group. These properties, resulting from the complex crystal chemistry and small particle size of smectites, include various layer charge, swelling capacity, and cation exchange capacity. In Brazil, the main bentonite deposits are located in the municipality of Boa Vista, Paraíba, which accounts for >70% of the country’s production. However, the progressive depletion of these varieties has motivated the search for new deposits. Among them, the Formosa deposit, in the state of Maranhão, stands out. Although both the Boa Vista and, to a lesser extent, the Formosa bentonites have been extensively studied in their <2 μm or coarser fractions, the crystal chemistry of their smectites has not yet been fully elucidated. This is due not only to the typical chemical and structural complexity of smectites, but also to the difficulty of obtaining pure smectite phases and the interference of accessory minerals. In this context, this thesis presents a detailed study of the crystal chemistry of smectite from the Formosa deposit, comparing it with three commercial varieties from Boa Vista: Bofe, Chocolate, and Verde Lodo. The <2 μm, 0.1-2 μm, and <0.1 μm fractions were analyzed, with the latter being the main focus of the study. The analyses included XRD (Rietveld method), FTIR, TEM-EDS, SEM, XRF, AAS, TG, and Mössbauer spectroscopy. These smectites, previously described as montmorillonites, also exhibit significant tetrahedral layer charge. In fact, the four samples show a tetrahedral charge of approximately 0.15 per half unit cell, sufficient to induce swelling after the Hofmann-Klemen treatment. The octahedral symmetry of all four samples was trans-vacant, influenced by both the Fe content and the tetrahedral charge. The structural and chemical similarities between the Formosa and Boa Vista smectites, along with similar smectite content in the <2 μm and <0.1 μm fractions – as quantified by the Rietveld method – demonstrated that the Formosa deposit is a potential alternative to the Boa Vista bentonites.
Acesso aberto (Open Access)
Influência da razão Al/argila no processo de pilarização de esmectita
(2006-09) GUERRA, Denis de Jesus Lima; LEMOS, Vanda Porpino; ANGÉLICA, Rômulo Simões; AIROLDI, Claudio
Smectite-type clays from the state of Pará, Brazil, were characterized by XRD, 27Al MAS NMR, FTIR and textural analysis by nitrogen adsorpition-desorption isotherms. In the production of pillared clays, the Al13 ion (keggin's ion) was used. This ion was obtained by the reaction of AlCl36H2O/NaOH solutions with OH/Al=2 molar ratio and with Al/clay ratios of 5, 10, 15, 20, 25 meq/g of clay, intercalated at 25 ºC during 3 h and calcined at 450 ºC (adequate temperature for calcination). The results showed that the pillarization process increased the basal spaces of the natural clay from 14.02 to 18.84 Å and the surface area from 44.30 to 198.03 m2/g (Al/g of clay = 25 meq/g of clay, pH=4). Materials prepared with different Al/g clay ratio showed the maximum Al incorporation for Al/g of clay = 25 meq/g of clay. The thermal stability of the natural clay was improved by the pillaring procedure.
Acesso aberto (Open Access)
Influência da temperatura de formação do íon de Keggin no processo de pilarização de esmectitas
(2005) GUERRA, Denis de Jesus Lima; LEMOS, Vanda Porpino; FERNANDES, Erlyson Farias; ANGÉLICA, Rômulo Simões; COSTA, Marcondes Lima da
Clays pillared with Keggin ions (AL-PILC) have been synthesized at OH/Al=2 molar ratio and various pretreatment temperatures (ambient temperature to 105ºC) in order to determine the optimum preparation conditions of the pillaring agent (Al13). The evolution of basal spacing, FTIR spectra, TG-curves, surface area and pillars number in function of temperatures of Al13 formation were studied. It was observed an increase number pillars and surface area at low temperatures.
Acesso aberto (Open Access)
Influência de argilas pilarizadas na decomposição catalítica do óleo de andiroba
(2007) GUERRA, Denis de Jesus Lima; LEMOS, Vanda Porpino; ANGÉLICA, Rômulo Simões; AIROLDI, Claudio
Smectite-bearing clay samples from Pará state, Amazon region, Brazil, were used for pillaring process in the present study. The natural and pillarized matrices were characterized using XRD and textural analysis using nitrogen adsorption-desorption isotherms. The ions of intercalation (Al13, Ti, Zr) were obtained through chemical reactions of AlCl36H2O/ NaOH, titanium ethoxide /HCl, zirconium acetate /HCl solutions. The Results showed that the pillarization process increases the basal spacing of the natural clay from 15.6 to 20.64 Å and the superficial area from 44 to 358 m2/g (Zr-PILC). The thermal stability of the natural clay was improved by the pillaring procedure. The resulting materials were submitted to catalytic process of decomposition of andiroba oil in a fix bed reactor at 673 ± 1 K. The catalytic activity was determined by the product composition resulting from the chemical reactions. The physicochemical parameters of the catalysts were obtained using XRD, FTIR and textural analysis. The pillared clays showed higher Brønsted acidity, with higher concentration in aromatic hydrocarbons and small concentration of aliphatic hydrocarbons.
Acesso aberto (Open Access)
Influência do método de síntese no processo de pilarização com titânio de uma esmectita da região amazônica
(2006-12) GUERRA, Denis de Jesus Lima; LEMOS, Vanda Porpino; ANGÉLICA, Rômulo Simões; AIROLDI, Claudio
Smectite clays of the State of Acre, Brazil, were used for the pillarization process. The natural and pillarized matrices were characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermal analysis, scanning electron microscopy, energy dispersive spectroscopy and textural analysis. The titanium pillarized solutions Ti(OC2H5)4 and TiCl4 were analyzed by FTIR. The intercalation ion was obtained by reacting Ti(OC2H5)4 with HCl (HCl/Ti ~ 1) and TiCl4 with ethanol (Ti/clay ~ 25 mmol Ti/g). The notronite intercalation was carried out using two methods: with dropwise hydrochloric acid in titanium ethoxide solution, and using titanium tetrachloride, kept under vigorous stirring at 25 °C for 3 h and calcination at 450 °C and 600 °C. The X-ray diffraction results of the pillarization process show an increase (15.30 Å to 18.76 Å) in the basal spacing of the natural clay and in the specific surface area (44.37 m2/g to 188.72 m2/g) The thermal stability of the natural clay was improved by the pillarization procedure.
Acesso aberto (Open Access)
Mineralogia e geoquímica da ocorrência de palygorskita de Alcântara, bacia de S. Luís-Grajaú, Maranhão
(2011-12) AMORIM, Kamilla Borges; ANGÉLICA, Rômulo Simões
The Alcântara Formation (S. Luis-Grajaú Basin, Alcântara region, northern Brazil) is mainly constituted by mudstones, sandstones and limestones. These lithotypes represent a progradacional succession of lagun/washover and tidal channel deposits that overlap huge shoreface deposits. The main purpose of this work is to carry out a mineralogical and geochemical characterization of the clay minerals association related to the pelitic rocks of the Alcantara Formation, specially the known palygorskite occurrences. One geological profile was sampled (eight samples) and described at the Baronesa beach (Alcântara city). The samples were submitted to mineralogical and chemical analysis by means of the following techniques: X-ray diffraction, X-ray fluorescence, thermal analysis (TG-DTA) and scanning electron microscopy. The results showed that the Baronesa Beach profile is mainly composed by sandstones at the base, followed by mudstones with intercalations of limestones. A wide clay mineral assemblage was described in a lagoon environment, with different contents of palygorskite, chlorite, illite, smectite and traces of kaolinite. Small amounts of dolomite, calcite and feldspars were also observed. The genesis of these minerals assemblage are mainly related to arid to semi-arid climatic conditions during the deposition period, with high evaporation rates. Two generations of palygorskite were described: (1) white macroscopic accumulations easily observed in the field and frequently described in the literature; and (2) massive accumulation, as the dominant mineral, in the upper muddy levels of the Baronesa Beach profile. This second generation is described for the first time in this work, and may constitute metric levels with potential economic interest.
Acesso aberto (Open Access)
Mineralogia e geoquímica dos sedimentos de fundo do rio-lago Tapajós-Pa.
(Universidade Federal do Pará, 2019-05-15) GOZZI, Priscila Valéria Tavares; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The Tapajós River experienced changes in its sedimentary load after the sea level in the Middle Holocene. The river’s mouth had its sedimentary load altered due to the difference of the density of its waters in relation to those of the Amazonas River, which created a physical barrier and drowned the mouth of the Tapajós River between the cities of Aveiro and Santarém. Thus, this part of the Tapajós River is nowadays better described as Lake Tapajós. Aiming the characterization of the Lake Tapajós, as well as the geological source of its sediments, samples from the water-sediment interface and from boreholes (90 cm) were collected and submitted to sedimentological, mineralogical and geochemical studies. The results show that the samples of the water-sediment interface are predominantly sandy, whereas the boreholes profiles are silty and composed by quartz, kaolinite, illite, muscovite, with goethite, gibbsite, anatase and smectite, showing a common mineralogical composition found in the terrains surrounding the lake. The occurrence of smectites suggests they are from the following different sources: Amazonas River, rocks of the sedimentary basin and partially weathered rocks from the Lake Tapajós upstream. The heavy mineral assemblage, predominantly composed by ultra-stable minerals, indicates recycling of these minerals, originally from primary sources as igneous and metamorphic rocks. The preferential distribution of sandy sediments in the margins and silty and clay in the central part of the lake, as well as the cyclical variation in the chemical composition along the borehole profiles, mainly in the southern portion of the lake, reinforces the lacustrine environment at least in the last 90 cm depth.
Acesso aberto (Open Access)
Ocorrência de uma nova bentonita brasileira nos basaltos intemperizados da formação Mosquito, bacia do Parnaíba, sul do Maranhão
(2011-12) PAZ, Simone Patrícia Aranha da; NEVES, Roberto de Freitas; NEUMANN, Reiner; COSTA, Geraldo Magela da
Extensive weathered basalt outcrops can be found in the vicinities of the Formosa da Serra Negra town, southern of Maranhão state, northern Brazil. They exhibit typical clay texture and an enormous potential to be used and explored as bentonite. This work deals with the chemical and mineralogical characterization of this material that has been named as Formosa Bentonite. The main following methods and analytical techniques were used: XRD, XRF, SEM, Mössbauer spectroscopy and CEC in total sample and after grain size separation. Two samples from the main Brazilian "Paraíba bentonites" (Chocolate and Bofe types) were used for comparison purposes. The results show that the Formosa bentonite exhibit some chemical and mineralogical differences in comparison with the two reference samples, although the main and most important feature is the presence of montmorillonite as the major mineral phase.
Acesso aberto (Open Access)
Síntese e caracterização de argila esmectita Zn-estevensita
(2014-06) HILDEBRANDO, Edemarino Araujo; VALENZUELA, Maria das Graças da Silva; NEVES, Roberto de Freitas; DIAZ, Francisco Rolando Valenzuela
Clay of the smectite group was successfully obtained at a low temperature hydrothermal processing using sodium metasilicate, zinc nitrate and urea as precursor materials. During the synthesis step, the molar composition of the mixture and the temperature remained constant varying the reaction time. The synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, diffuse reflectance Fourier Transform infrared spectroscopy, differential thermal analysis and thermogravimetry, cation exchange capacity (CEC) and BET surface area measurements. The results show that in the methodology utilized is obtained Zn-stevensite with specific surface area of 171.6-203.4 m2/g and good crystallinity as present single phase in the reaction product after static synthesis at 90 ºC for 44 to 138 h, indicating that, the increased synthesis time is an important parameter for crystallization process of the clay.
Acesso aberto (Open Access)
Síntese e caracterização de materiais híbridos (PCHs e Organoargilas) com aplicabilidade na adsorção de fenol, benzeno e tolueno
(Universidade Federal do Pará, 2013-12-18) SANTOS, Sheila Silva dos; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
This study evaluates the use of smectite from Acre/Brazil as a precursor in the synthesis of Porous Clay heterostructure and organofunctionalization with mercaptopropyltrimethoxysilane (MPTS-Arg) and applicability of these materials as adsorbents for phenol, benzene and toluene in the liquid phase. The synthesis of PCH involves the following steps: preparation of organoclay with hexadecyltrimethylammonium (HDTMA-clay); it increases the basal spacing (d001) of organoclay using the co-surfactant octylamine and concomitant addition of a source of Si, such as tetraethylorthosilicate (TEOS) , washing with HCl in ethanol and drying at 60 º C (PCH-60 A and B); calcination at 500 ° C and 700 ° C (PCH 500 A /B and PCH 700) by removing the surfactant / co-surfactant and subsequent replacement of these organic substances by protons that remain on the walls of galleries SiO pillars to new treatment perhaps held at PCH. The material MPTS-Arg was obtained from the intercalation of the original clay with mercaptopropiltrimetoxisilano stirring for 1 h (MPTS Arg-1) and the original clay pre-treated with HCl 1 mol L-1 and stirred for 2 h (Arg-MPOS 2).The materials (clay original HDTMA-Clay, PCH-60, Arg-PCH-500/700 and MPTS) were characterized by X-ray diffraction (XRD), scanning electron microscopy coupled to X-ray spectroscopy and energy dispersive (SEM / EDS), molecular absorption spectroscopy with Fourier transform IR (FTIR), thermal analysis techniques (DTA_TG) and textural analyzes, such as specific surface area measurements (ASE BET, ASELangmuir), total pore volume (TPV) and average pore diameter (APD). Additional characterization by nuclear magnetic resonance in solid coupled to mass spectrometry (NMR-MAS) was conducted for the PCH-500 A. In the experiments adsorption of phenol, benzene and toluene were used aqueous suspensions containing adsorbents of the separately adsorbates. The equilibrium concentrations of phenol, toluene and benzene were measured by molecular absorption spectroscopy in the ultraviolet region, as accepted method is applied in other adsorption studies. We obtained the following results: identification of smectite clay minerals in natural clay with basal spacing of 1.25 nm; intercalation of HDTMA and MPTS with expansion of d (001) to 1.95 nm (HDTMA-Arg 5) and 2.1 nm (MPTS Clay-1h). After modification was observed by EDS analysis a decrease of the concentrations of elements Na, Si and Al (%) and the increase in interlayer positions concentration C. The 29Si MAS NMR spectrum of the PCH A-500 showed signs of chemical center Q3 Si (OSi)3OH and Q4 Si(OSi)4 indicate that the formation of silica in its structure. The PCHs (60 and 500 A) were classified as mesoporous, with ASE BET between 417-446 m2 g-1 and total pore volume (cm-3 g-1) = 0.367 to 0.369. Increasing calcination temperature of 500 to 700º C PCH (PCH 700) provided decrease in SBET (305 m2 g-1) and average pore diameter (0976 nm). It was found from the evaluation of the measures of pore diameter at 700 PCH that 46 % of the measurements correspond to micropores. The adsorption process obtained values for KL (mg L-1) , KF (mg L-1) and qmax (mg g-1) in the following cases : (i) adsorption of phenol (1.40, 2.26 and 3.80) and toluene (145, 18.7 and 135) in the PCH- 500 , (ii) adsorption of benzene (0.33 , 41.49 and 69.81) in PCH 500 B (iii) in toluene adsorption MPTS-Argila 1h (1.06 , 118.9 and 146) and MPTSArgila 2h (2.1 , 92 and 97) , (iv) adsorption of phenol (0.07, 4.44 and 12.48 ) and benzene (12.11, 4.95 and 35.8) in HDTMA-Arg 5, respectively. The data on the characterization of the materials indicated that the formation of PCH caused a large increase in the concentrations of Si and decrease in the concentrations of Al, Fe and other elements due to delamination - exfoliation of smectite original. It was verified that the materials are most suitable for the adsorption of toluene and benzene to phenol.
Acesso aberto (Open Access)
Síntese, caracterização e aplicação de esmectitas pilarizadas com Al, Ti
(Universidade Federal do Pará, 2006-02-21) GUERRA, Denis de Jesus Lima; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
Hidroxi-polymers of Al and Ti were synthesized after hydrolysis of its respective salts and are being used in the intercalation and pillarization of smectites of different chemical composition. The intercalation methodology consists mainly in the substitution of interlamelar cations by bigger cations {aluminium polyhroxipolymer so-called Keggin ion, Al13 complex, [Al13O4(OH)24(H2O)12]7+ and Titanium polyoxycation, TiOx(OH)2x} followed by further drying at 80ºC. The resultant material of the intercalation must suffer calcinations at T=300-500ºC (pillarization), with the main purpose of removing interlayer water. The natural and pillared clays were characterized by XRD, FTIR, 27Al and 29Si NMR, TGA-TG and textural analysis using N2 adsorption/desorption isotherms. The samples were used as adsorbents in the adsorption process with butylamine (Al-PILC/acid activation) and Cu2+, Ni2+ and Co2+ solutions (Al-PILC and Ti-PILC). The results of XRD patterns show that the d(001) spacing increases of d001= 15,30-15,60 to d001= 18,36-18,92 Å (Al-PILC) and of d001= 15,30 to d001= 17,10-19,56. Å (Ti-PILC). FTIR spectra have proved smectites pillarization with Al and Ti by vibrations at 667 cm-1 (Al- O bond of tetrahedrally coordinated Al cations in the center of the Al13 pillars) and 1338 cm-1 (Ti-O bond of the TiO2 pillars). The 27Al RMN spectra show that Al-PILC samples presents signals of 68 ppm and 0 ppm related to the Al in the tetrahedral and octahedral positions, respectively. It was indicate that the TGA-TG curves are similar itself. Endothermic peaks were observed. The first one occurs at 100-200 ºC and is assigned to loss of surface physisorbed water and loosely coordinated water. The second occurs at 300-600 ºC corresponding to the dehydroxilation of the Hidroxi-polymers. Textural parameters have also increased which resulted in the classification of this pillared smectites as a microporous to mesoporous material. The adsorption of butylamine and Cu2+, Ni2+ and Co2+ ions from aqueous solution in room temperature onto PILCs show that the Langmuir, Freundlich and Temkin adsorption isotherms models have been applied to fit the experimental data by linear regression. The onesurface Langmuir equation provided the best fit to the data (r=0,999). The Freundlich equation presented limitations in rises concentrations, but acceptable values of parameters were obtained (Kf and n) with the use of the three models. The parameters were used to calculate the amount adsorbed (Nf), a function of Cs.
Acesso aberto (Open Access)
Sorção de Ni e azul de metileno em esmectita do Rio Branco-Acre sob tratamento com cátion orgânico
(Universidade Federal do Pará, 2008-03-19) SILVA, Tatiani da Luz; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
The interaction among organic cations, as the methylene blue (AM), benzyltrimethylammonium (BTMA) and clay minerals of the group of the smectites they result in the formation of applied materials in the adsorption of organic pollutant presents in waters, soils and you cultivate. In this work they were prepared the adsorbents (organic–clays) smectite - AM and smectite–BTMA, with the following objectives: the use of the clay minerals covering observed at several places of the municipal district of Rio Branco – Acre, as organic-clay precursor, with applicability of absorption of heavy metals and organic substances; the principal chemical and mineralogical attributes of the precursory clay determination, that are necessary requirements the interpretation of the mechanisms of interaction organic clay/cation and metallic organic-clay/cation; the study of the processes of adsorption of the organic-clays; the evaluation of the efficiency of the organic - clays in the nickel adsorption. The precursory sample of smectite was collected in Rio Branco–Acre, being used in the tests of adsorption and in the treatment with the organic cations the fraction clay mineral (F-Esmec) and the total fraction (FT-IR) of the sample. They were also used an smectite sample collected in Sena Madureira (SM)–Acre already characterized in previous work and a sample of standard smectite Swy-2-Na-Montmorillonite (SWy-2) of Wymong - USA. The mineralogical analysis was accomplished with base in the data of difraction of DRX, to FT-IR, MEV and ATD-ATG. The organic agents selected for this study they were: Methylene Blue, denominated AM and Benzyltrimethylammonium, denominated BTMA. The interaction processes between clay and organic cations were investigated through data obtained by molecular spectroscopy in the area of IV, ATD-ATG, MEV and DRX. The adsorbents were applied in the adsorption of AM and Ni in aqueous head offices (concentrations varying from 1 to 10 ppm). The concentrations of AM and Ni before and after the adsorption they were certain for spectrophotometry in the area UV for AM (λ= 670 nm) and for atomic absorption for determination of the concentration of Ni (λ = 232 nm). The clay sample collected in Rio Branco–Acre is constituted mainly by quartz, the most abundant, smectite, illita and caulinita, and of the clay minerals the smectites are the predominant ones in the clay sample. The basal spacings of the samples didn't change significantly with the adsorption of AM and of BTMA, as observed in works found in the literature. They were appraised the capacities adsorptive of the treated samples with BTMA being used AM as adsorvate. The results of these evaluations detected that ran total adsorption of AM (concentrations varying from 1 to 10 ppm) for the treated samples with BTMA, being also this behavior verified in experiences accomplished for: Gersti and Mingelgrin (1979), Mortland (1979), Boyd et al (1988), Margulies et al (1988), that in your studies evidence the organophilic interactions. Like this being, the samples presented plausible results as the adsorption of Ni and AM, being the clays of precursory of the organic-clays good Acre: smectite–AM and smectite–BTMA. In the tests of adsorption accomplished with solutions Ni2+ the amount adsorved (mg.g-1) it happened in the following order: F-Esmec-BTMA > F-Esmec. The organic cation, BTMA, interacting with the surfaces of the natural clay was more efficient in the adsorption of AM than the clay without the previous treatment with this salt. To evaluate the time that the sample F-Esmec should be in contact under agitation with the solution of Ni, three isotherms of adsorption were accomplished, where the time of agitation of the solution of Ni in contact with the clay varied in 1h, 12hs and 24 hs. The experiments showed that 1h are the enough time that the sample should be under agitation with the solution of Ni to obtain good results of adsorption because the value of Q, in mg/g, of Ni adsorbed after 24 h of agitation of the solution was practically the same obtained under agitation by 1h. The treatment of the clay with BTMA increased an amount adsorbed of the present nickel in aqueous solutions, as well as happened him in the tests of adsorption with AM. This is due the existent specific interactions between adsorbent and adsorvate, as foreseen by Gersti and Mingelgrin (1979). In all the tests of adsorption, the fraction F-Esmec was the one that it presented better result of adsorption.