Sorção de Ni e azul de metileno em esmectita do Rio Branco-Acre sob tratamento com cátion orgânico

Abstract

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.