Abstract
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.
Highlights
The environmental impacts mainly originated by the constant discharge of all types of industrial pollutants by using water at some stage of the process reduce the self purifying ability of water
This study aimed to evaluate the potential of an alternative adsorbent such as sodium bentonite clay, commercially called as Fluidgel, for the removal of Pb2+ present in aqueous effluents in dynamic system
It can be observed (Table 1) that for the flowrate of 1 mL/min. a relative low value of mass transfer zone (MTZ) length (3.4 cm) as well as a low resistance to mass transfer, observed by the jump in the curve after the breakthrough point (Figure 1) for lead removal by the clay, in addition to the greater percentage removal (47.03%). For this reason the flowrate selected to be used in other experiments of lead removal with Fluidgel TACal was 1 ml/min
Summary
The environmental impacts mainly originated by the constant discharge of all types of industrial pollutants by using water at some stage of the process reduce the self purifying ability of water. The pollutants present in water interferes with the metabolic cycles, due to the toxic effects they have on microorganisms. Some metals are essential for numerous metabolic processes, all metals are potentially toxic, carcinogenic and mutagenic if used excessively. Traditional processes have been employed, along with new technologies, with the aim of contributing to the removal of metals present in the effluent wastewater[1]. Among various existing processes there are: ion exchange[2], the chemical precipitation[3] and ultrafiltration[4]. These methods are not always effective, and usuallyhave high cost and generate waste, requiring a further stage of treatment
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