Navegando por Orientadores "LEMOS, Vanda Porpino"

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Adsorção de cromato em materiais sintetizados a partir de rejeito de caulim do rio Capim
(Universidade Federal do Pará, 2008-05-13) MORAES, Milena Carvalho de; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
Industrial and domestic waste cause serious problems for the environment. Industries treatment of kaolin have been deposited reject in large lakes of sedimentation and this has caused accidents as occurred in august/2007 and February/2008. The large volume of kaolin in the lakes sedimentation invaded lakes and rivers from Rio Capim, Para region. This fact resulted in the pollution of waters and death of fish. This problem can be minimized with the use of kaolin reject (KR) in the synthesis of new materials. In this work was used KR treated with organic acid (glycine at concentrations of 5%, 10% and 15% , being obtained the adsorbents: KR-gly-5, KRgly-10 and KL-gly-15, respectively) and mixture NaClO4:HClO4 (proportions 1:50 and 1:75, being obtained the adsorbents KR-NaClO4:HClO4-1:50 and KR- NaClO4:HClO4- 1:75, respectively) and KR as source of Si and Al in the synthesis of zeolites. The materials were characterized by chemical composition and XRD, FTIR, DTA-TG and SEM data. These materials were studied in adsorption process for CrO4 2- from aqueous solutions. The results obtained indicate that the CrO4 2- is adsorbed by kaolin reject and other materials from KR followed this order: KR-gly-10> KR-gly-5>KR-gly-15>KG> KR- NaClO4:HClO4- 1:75> zeolites.
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)
Adsorção de nitrato em rejeito de caulim organofuncionalizado com uréia
(Universidade Federal do Pará, 2012-05-30) TAVARES, Laís Conceição; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
Kaolin waste, generated in abundance by companies from Pará state, has caused to the environmental problems. In order to give input on the reuse of this waste was evaluated retention of nitrate ions on kaolin waste natural and modified with urea and studied the equilibrium of adsorption processes at solid-solution interfaces. The materials were characterized by X-ray diffraction and X-ray fluorescence (XRF and XRD, respectiely), IR spectroscopy (FTIR spectrum), scanning electron microscopy and estimated data of surface charge. Adsorption experiments of nitrate ions in the waste natural kaolin (CRJN) and modified with urea (CRJU) were performed without pH adjustment. H + concentrations were measured by direct potentiometry before and after the process of adsorption and equilibrium concentrations of nitrate were measured by ion chromatography. The results indicated: high purity kaolin waste; formation of kaolinite-urea complex confirmed by XRD reflection at 2  8,28o e d = 1.068 nm and the FTIR spectrum with the appearance of a broad band of low intensity, containing two discrete shoulder around 3500-3380 cm-1, corresponding to asymmetric and symmetric vibrations of the group-NH2 of urea-kaolinite, superimposed to the vibration of water. surface charges data, suggesting that the materials have a higher capacity to adsorb cations than anions, but depending on the concentration of H + and OH- on adsorbent, the hydroxyl surface can be protonated yielding positive charges that are reflected in the adsorption of anions, obtaining significant adsorbed nitrate, both in CRJN as CRJU (0,27-0,73 and from 0,18-0,70 3.5 mg g-1, respectively), the separation coefficient (RL) of from 0,28 to 0,828 change in free energy ΔG ° = -2,094 to + 0,445 kJ mol-1 for CRJN and ΔG° = -1,036 to + 1,32 kJ mol-1 for CRJN molecule. The data from RL indicated that the adsorption processes are less favorable in most points of the adsorption processes and based on the results of the free energy change (ΔG º) was showed low spontaneity to no spontaneity and adsorption processes are physical.
Acesso aberto (Open Access)
Adsorção de Pb por caulinita tratada com ácidos acético e cítrico
(Universidade Federal do Pará, 2005) SENA, Luciana Freitas de; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
Acesso aberto (Open Access)
Adsorção simultânea de íons níquel, zinco e cobre em sedimentos argilosos da Formação Solimões no estado do Acre
(Universidade Federal do Pará, 2011-09-02) CARDOSO, Vivian Mariana Miranda; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
Torrential rains in the Amazon region provide large leaching of micronutrients, which can be controlled from the adsorption reactions of micronutrients in clay minerals. Studies on the geochemical properties of sediment containing high concentrations of clay minerals in the adsorption reactions of micronutrients is a research topic of great importance considering the proven use of clay minerals with a wide range of applications in various processes and procedures adsorption, involving the remediation of sediment, purification of air and water. In order to make contributions on the physical and chemical properties of soils and applicability of the Solimões Formation from Acre State was carried out a study to simulate natural competitive adsorption of micronutrients cobre, níquel e zinco in different adsorbents sites present in these sediment and to evaluate the influence of the attributes mineralogical, chemical and physico-chemical from these adsorption processes. Preliminary data on the mineralogy of soil samples allowed to select four stations distributed among four named as H1RA, H6B, H23A H9F and located along the BR 364 and BR 317, as well as outcrops in the river Acre. Analyses of samples were performed by XRD (using the powder in the range 2θ=o 5-75 ; analysis of clay fraction in sheets oriented air-dried in an atmosphere of ethylene glycol o and heated at 550 ° C (2θ = 3 -35 ) analysis total chemical by ICP-OES; element analysis exchangeable and available to determine parameters of soil fertility. In adsorption experiments the equilibrium concentrations of cobre, níquel and zinco were determined by AAS. We used the models of Langmuir isotherm, Sips, Toth, Temkin Rendlich-Petersen and the fit of the experimental data of adsorption. The results indicated that the samples present as major minerals quartz and clay minerals of the smectite group, mica and kaolinite mineral and the 14th (H6B) preliminarily identified as interstratified mica-chlorite smectite-mica or chlorite-vermiculite. The other minerals identified in the samples were gypsum (H1RA), microcline (H6B and H9F) and albite (H9F). The average chemical composition is represented by 60.99% SiO2, 15.91% Al2O3, 5.84% of Fe2O3, 2.21% K2O, 0.34% of Na2O, 1.26% MgO, 0.86% CaO and 0.86% TiO2. The following ranges were obtained for the parameters of fertility: pHH2O = 5.24 to 8.36; pHKCl = 3.16 to 7.02; CTCefetiva = 3.37 to 25.42 cmol c / kg;% V (base saturation) = 83.08 to 97.63; saturation% Ca = 4.28 to 69.21; saturation% = 11.32 to 76.42 Mg, K saturation% = 2.32 to 17.32;. In the adsorption experiments were obtained the following ranges for the amount of each element adsorbed (mg / g) in soil samples selected: Cu) from 91.30 to 147.46 in H1RA, 47.25 to 83.93 in H6B , 67.13 to 137.36 in H9F; 73.01 to 141.35 in H23A, Ni) from 49.97 to 93.81 in H1RA; 42.51 to 113.44 in H6B; 62.52 to 134.86 in H9F; 54.13 to 172.58 in H23A, Zn) from 50.11 to 104.50 in H1RA, 44.31 to 64.12 in H6B; 60.21 to 89.91 in H9F; 73.84-135 , 60 in H23A. In these experiments was obtained the following values for the initial pH of the aqueous suspensions of samples in H1RA pHinicial=3.88 to 5.38; in pHinicial H6B = 2.71 to 3.27; H9F in pHinicial = 3.16 to 4, 24 and in pHinicial H23A = 2.61 to 3.29. The values of pH equilibrium were 4.38 to 5.2 in the H1RA sample, 2.71 to 3.16 in H6B; 3.24 to 4.2 in H9F; 2.51 to 3.14.in H23A. It was concluded that the sediment samples analyzed have suitable properties adsorptive for simultaneous retention of Cobre, níquel and zinco in water; the samples with montmorilonite (station H23A) and mineral 14A (H6B) present adsorption of metals transition at pH values between 2.5 and 3.1. The samples H1RA H9F with different groups of clay minerals (smectite, kaolinite and mica) the adsorption of transition metals occurs at pH values between 3.2 to 5.5. The ionic strength increases with decreasing pH . The best isotherm models to describe adsorption processes of Cobre, níquel and zinco in sediment samples were the Langmuir and Sips models. The values of ns Sips indicated that the majority of adsorption systems fall between the homogeneous heterogeneous systems. The equilibrium data and thermodynamic processes of simultaneous interaction between these ions and mineral adsorbents indicated that the processes are favorable, spontaneous and the type of adsorption is specific (chemical adsorption) with the formation of inner sphere complexes.
Acesso aberto (Open Access)
Assinaturas geoquímicas dos perfis de solo do sítio arqueológico do município Bom Jesus do Tocantins – Pará
(Universidade Federal do Pará, 2010-12-07) SILVA, Any Kelly Terra da; KERN, Dirse Clara; http://lattes.cnpq.br/8351785832221386; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
The integration of morphological, mineralogical and chemical data of a soil with Archeological Black Earth (ABE) and surrounding Argissolos allowed to indentify the main process acting on the ABE formation from Bom Jesus do Tocantins, southeast Pará State. The similarity between these data in the subsurface horizon of ABE and surrounding soils indicate that ABE was probably developed from Argissolos with subsequent pedogenetic transformation through the input of organic and inorganic materials (kitchenware, foods and other materials of animal and vegetable origin) by ancient human settlements that promoted the thickness of the surface horizon and higher concentrations of CaO, P2O5, Zn, available P and Zn, and exchangeable Ca and Mg in relation to surrounding Argissolos. Furthermore, this anthropic influence also resulted in changes of subsurface horizon of Argissolos with ABE, such as high concentrations of P2O5 and available P. The Soil Taxonomy and Brazilian System of Soil Classification (BSSC) are suitable to identify ABE, since they prioritize in the soil orders the main pedogenetic process acting on soil formation and development, related to the subsurface horizon, and subsequent pedogenetic transformations in the surface horizon. Moreover, this study propose the addition of diagnostic properties such as ceramic and lithic artifacts, P2O5 and available P and Zn, organic carbon, Ca2++ Mg2+, CEC and base saturation index in the surface horizon of Soil Taxonomy and BSSC to group and differentiate several types of anthropic soils of Amazon region.
Acesso aberto (Open Access)
lndicadores de estabilidade da matéria orgânica em terras pretas nos sítios arqueológicos Jabuti e Jacarequara (Pará)
(Universidade Federal do Pará, 2015-09-02) SENA, Luciana Freitas de; KERN, Dirse Clara; http://lattes.cnpq.br/8351785832221386; 8351785832221386; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008; 1829861620854008
Environmental conditions in the Amazon region favor the weathering and decomposition of soil organic matter, making it depleted in nutrients and difficult agricultural use. But in the same region, areas that have been modified by human action preterit, known as Terra Preta Archaeological (TPA), have different properties, among which stands out the high stability of soil organic matter (SOM) that in some research it is attributed to interactions between the MOS and other soil constituents such as pyrogenic carbon and minerals from the soil. In this study were selected two archaeological sites in the state of Pará, the Jabuti, the cemetery housing type, located in the city of Bragança, and the Jacarequara, the sambaqui type, located in Barcarena, in order to assess the stability of organic matter TPA from soil extracted solutions (depths 30 and 80 cm) and own soil (collected during the implementation of extractors in December 2013) in areas of TPA and vicinity. The characterization of soil solutions was conducted in the period between March and June 2013, based on the macroscopic properties and the chemical indicators: dissolved carbon concentrations (organic, inorganic and total), determined by the combustion method; pH, Eh and conductivity. The SOM stability assessments in the solid phases of the TPA and surrounding areas (ADJ) were based on textural verification of soil chemical indicators (pH, organic carbon concentrations and Ca, K, P, Na, and Mg) and biological represented by the microbial biomass, determined by the method of irradiation / extraction and expressed in terms of carbon (Cbm) and nitrogen (Nbm). The results of the soil solutions showed that two sites in the pH values are higher in depth (80 cm), and at the site Jacarequara values were determined for this parameter up to 7.2, while the site Jabuti pH results do not exceed the value 6. The maximum values of Eh (mV), conductivity (μs) and dissolved organic carbon (mg L-1) in place Jacarequara, 30 cm deep were respectively +201 mV, 427 µs e 13 mg L-1 and in the area adjacent to this site, at the same depth the highest values were +128 mV, 72 µs e 23 mg L-1 for the same parameters. At the Jabuti site and its ADJ, in 30 cm deep, the respective maximum values of the same areas were Eh +108 mV and +96 mV; conductivity 138.87µs and 59.85µs, dissolved organic carbon 12 mg L-1 and 21.08 mg L-1. Comparing the areas of TPA and their ADJ, the data Eh and dissolved organic carbon refer to more stable components in soil areas of solutions of TPA, owing to the more oxidizing values and smaller dissolved organic carbon concentrations, the results conductivity, which is an indicator of the concentration of ions is higher in the TPA reporting the increased availability of nutrients. In both sites, soils presented sandy texture, both in the areas of TPA as the ADJ, the latter being more sandy. In the soil Jacarequara site and its ADJ in the range of 20 to 30 cm deep, the following values were obtained respectively: 119.82 g kg-1 and 20.34 g kg-1 for SOM; pHH2O equal to 6.8 and 4.9; 183 mg/dm3 and 5 mg/dm3 P (available); 39 mg/dm3 and 29 mg/dm3 K (exchangeable); 14.8 cmolc/dm3 and 0.7 cmolc/dm3 Ca (exchangeable); 0.1 cmolc/dm3 and 1.7 cmolc/dm3 Al (exchangeable), 181.26 μg g-1 and 88.74 μg g-1 of Cbm and 3.27 mg kg-1 and 1.91 mg kg-1 Nbm. In the soil of Jabuti site, the determined values were: 83.66 g kg-1 of MOS, pHH2O equal to 4.4; 55 mg/dm3 P (available); 59 mg/dm3 K (exchangeable); 0.3 cmolc/dm3 Ca (exchangeable); 4 cmolc/dm3 of Al (exchangeable); 92.56 mg kg-1 of Cbm and 1.41 mg kg-1 Nbm; in the area adjacent to this site, the values were: 13.13 g kg-1 of MOS, pHH2O equal to 4.6; 4 mg/dm3 P (available); 29 mg dm3 K (exchangeable); 0.3 cmolc/dm3 Ca (exchangeable); 1 cmolc/dm3 Al (exchangeable), 27.54 mg kg-1 of Cbm and 0.96 mg kg-1 Nbm. As well as other archaeological sites with TPA, Jacarequara and the Jabuti had significantly higher levels of nutrients compared to surrounding areas, with the exception of Ca element in Jabuti. In the sites, carbonaceous particles were investigated, showing no intrinsic results pyrogenic carbon. In areas of TPA, the results obtained from the soil analysis indicated positive correlation between the microbial biomass, organic matter and nutrients, which can be associated with better quality of the soil in these areas compared their ADJ, consistently with the data highlighted in the soil solutions. Comparing the two sites, the results indicate that the SOM in Jacarequara site shows more stable constituents.
Acesso aberto (Open Access)
Materiais de interações biocarvões/latossolo: caracterização química e físico-química
(Universidade Federal do Pará, 2019-04-17) MACHADO, Marcelly Christian Galvão Rodrigues; MORAES, Milena Carvalho de; http://lattes.cnpq.br/9699850614353792; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
The present study aims to obtain materials from thermochemical interactions biochars-latosoil and to evaluation its chemical and physicochemical properties inrelation to those indicated in high fertility soils. The key importance of this study involves: characteristics indicative of soil with high organic matter stability, as to those indicated for archeological black earth (ABE), due to the structural properties from crystalline and amorphous materials, associated to the organic aggregates, considered natural adsorbent in soils. The sources of biochar were leaves of cinnamon, cacau, cashew and ipê trees and to those for soil was latosoilsample fromthe Caxiuanã region/ Brazil-Pará. The characterization of the materials was performed based on analysis by spectral analytical methods [XRD, FTIR, EDS and MIRO-RAMAN].The results from XRD indicatedspecially characteristics of organic compounds, represented by hexagonal and rhombohedral graphites, turbostratic graphite and graphite oxide. Based elementaryanalysis were obtained atomic ratio O/C corresponding to carbonaceous materials with high aromaticity. Micro-Raman spectra shown bands D e G corresponding to HPA´s pyrene and naphthalene. The following conclusions were obtained: the materials from thermochemical interactions biochars-soil presents chemical and physicochemical properties corresponding to the organic aggregates common in soil with high stability; the presence of HPAs into materials shoud be considered negativefor to use biochars into soils, due to the possibility of contamination of the soil and groundwater.
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)
Síntese, caracterização físico-química e aplicação de alumínossilicatos como adsorventes
(Universidade Federal do Pará, 2003-05) CASTRO, Elton Anderson Santos de; LEMOS, Vanda Porpino; http://lattes.cnpq.br/1829861620854008
In this work three differente aluminosilicates were used for evaluation of the index of recovery of the coloring monovalent metilene blue. The no-porous clay mineral, Kaolinite, from Capim river area in Pará, Brazil, was treated with hydrochloric acid 5N in order to increase the specific area. The microporous molecular sieve, zeolite NaP, was synthesized through the hidrotermal method, with the kaolinite of Capim river area being used as source of Si and Al. The hidrotermal method was also used for the synthesis of the mesoporous molecular sieve Al-MCM-48, wich received thermal treatment (calcination) at 540ºC under flow of N2 and air for 7h to removal of the agent director (surfactant). The porous and no-porous materials were characterized by X-ray diffraction, infrared spectrophotometry, thermodifferential and termogravimetric analyses and adsorption and desorption methods with N2. Chemical analysis for the clay mineral has been performed and scanning electronic microscopy was used for the microporous aluminosilicate. These materials were tested as adsorbents in the recovery of the metilene blue at concentration of 6ppm, in different times (20, 40, 60 and 120min) with the contact method being used. The concentration, separation method of phases and the more appropriate wave length were studied. The determination of the recovery index for the organic coloring, using the three materials, was performed through visible spectrophotometry. XRD and chemical analysis results revealed the high purity of the clay mineral kaolinite. The specific surface area increased by 31,23% after acid activation. The specific area obtained for Al-MCM-48, was of 1219m2g-1, which is a characteristic value for this kind of materials. The results of XRD indicate that the zeolita NaP was formed, but traces of the feldspatoid hidroxysodalite are also present, what could be confirmed by the SEM images. The values of the recovery index for the metilene blue demonstrated that the kaolinite under acid activation was the most effective (100% of recovery), followed by the zeolite NaP (97,89% of recovery) and Al-MCM-48 (97,35% of recovery). The results indicate the viability of use of these materials as agents for pre-concentration in cromatographic analyses.
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.