The bentonitic clays show good adsorptive characteristics, being used as alternative material for removing metals. This study evaluates several treatments (calcination, acid activation and treatment with sodium) of bentonite type Bofe in the removal of nickel and copper. Analyses were performed for physicochemical characterization of clay using the techniques: X-ray fluorescence (XRF), thermal analysis (TG and DTA), X-ray Diffraction (XRD), the ethylene glycol monoethyl ether (EGME) method, N2 adsorption (BET) and Scanning Electron Microscopy (SEM). Among the changes induced by acid activation and sodium transformations, the treatment with sodium chloride in fixed bed showed the highest performance in the monocomponent removal of nickel and copper.

This study aims to characterize the complex metal-clay formed by adsorption of lead. In this work, the bentonite clay named Fluidgel was calcined at 750 ºC and was used as adsorbent for lead removal. The characterization of this clay and complex metal-clay was carried out by X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FTIR), surface area (BET method), scanning electron microscopy (SEM) and chemical composition by energy dispersive X-ray (EDX). The removal of lead from aqueous solution was carried out in a fixed bed. Dynamic experiments were performed to evaluate the effect of flowrate on adsorption efficiency. The experiments were accomplished at room temperature, the clay adsorbent particle diameter was of 0.855 mm and the flow rate varied from 0.6 to 2 mL/min. The feed concentration of lead was about 0.24 mmol/L. Comparing the chemical compositions of the clays obtained by EDX before and after removal of the lead, it was concluded that the ion exchange process might be important to lead removal. From the semi-quantitative analysis of chemical composition in clays with and without adsorbed lead it was observed a reduction of the amount of Ca2+, K+ cations and the disappearance of Na+ cations, which was caused by cation exchange process.

This study evaluated the kinetic adsorption of Pb and Cu ions using rice husk ash as adsorbent in a fixed bed. The maximum adsorption capacities obtained for lead and copper ions in the fixed bed were 0.0561 and 0.0682 mmol/g (at 20 ºC), respectively. The thermodynamic studies indicated that the lead adsorption process was exothermic and spontaneous, while the copper adsorption process was endothermic and spontaneous. Characterization results indicated the presence of several functional groups, amorphous silica and a fibrous and longitudinal structure of rice husks. Rice husk ash (RHA) from northern Brazil can be used as a bioadsorbent for the individual removal of Pb(II) and Cu(II) ions from metal-containing effluents.

A aplicação de argilas para adsorção de metais pesados presentes em efluentes tem sido objeto de estudo em muitas pesquisas em virtude das inúmeras vantagens técnicas e econômicas. Este trabalho teve como objetivo obtenção de isotermas de adsorção de níquel e zinco em coluna de leito fixo utilizando como adsorvente argila bentonita calcinada a 500 ºC. Os experimentos para remoção de níquel e zinco foram conduzidos à temperatura ambiente (20 ºC - 25 ºC), pH da alimentação ajustado em 4,5, massa de argila calcinada de 15,5 g, com diâmetro médio de 0,855 mm, vazão de alimentação de 4 mL/min e concentração da solução de metal variando entre 0,5 meq/L a 4 meq/L. Os modelos de isoterma de Langmuir, Freundlich, Langmuir-Freundlich, Radke-Prausnitz, Redlich-Peterson, Sips e Toth foram ajustados aos dados de equilíbrio, sendo que o modelo de Langmuir apresentou melhor ajuste às concentrações de Ni2+ e Zn2+ adsorvido.

The use of clays for adsorption of heavy metals in wastewater has been studied in many trials because of numerous technical and economic advantages. This work aimed to evaluate the removal of nickel and zinc in fixed bed column. The experiments for the removal of nickel and zinc were conducted at room temperature (20 ºC - 25 ºC), pH adjusted at 4.5, weight of 15.5 g calcined clay,with an average diameter of 0.855mm, feeding flow rate 4 mL/min and concentration of the solution of metal between 0.5 meq/L to 4 meq/L. The Langmuir, Freundlich, Langmuir-Freundlich, Radke-Prausnitz, Redlich-Peterson, Sips and Toth models were fitted to equilibrium data, and the Langmuir model provided the best fit for adsorption isotherms.

Este artigo tem como principal objetivo caracterizar argilas esmectíticas chocolate de Boa-Vista, Estado da Paraíba (Brasil) na sua forma natural e após tratamento químico, visando a sua utilização na remoção de Pb2+ de efluentes sintéticos. Os métodos de caracterização utilizados foram fluorescência de raios X, difração de raios X, microscopia eletrônica de varredura e espectroscopia de raios X por energia dispersiva. Neste trabalho foi estabelecido o procedimento para remoção de Pb2+ a partir de um efluente inorgânico sintético, utilizando argila natural. Para avaliar a influência dos principais parâmetros, como pH, tratamento e granulometria da argila sobre a remoção do Pb2+, foi utilizado o planejamento fatorial e os melhores resultados obtidos foram: pH 4,5, granulometria entre 35 e 48 mesh, e argila natural.

The main objective of this paper is to characterize the Chocolate smectite clays of Boa-Vista, State of Paraíba (Brazil), in their natural form, and after chemical treatment for their application in the removal of Pb2+ from synthetic effluents. The following methods were used: X-ray fluorescence, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. In is work the procedures for Pb2+ removal from a synthetic inorganic effluent using a natural clay were established. To evaluate the influence of the main parameters, such as pH, clay treatment and granulometry, on Pb2+ removal, factorial planning was used and the best results obtained were pH 4.5, granulometry in the range of 35 to 48 mesh and natural clay.