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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.