Abstract
In this study pequi (Caryocar brasiliense) shells were evaluated in relation to their potential for the adsorption of PbII ions in aqueous systems. The adsorbent was characterized by point of zero charge (PZC), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and PbII ions were detected by flame atomic absorption spectrometry (FAAS). The adsorption parameters studied were solution pH, adsorbent mass, contact time and the optimum adsorption conditions were found to be 7.0, 50 mg and 30 min, respectively, using 15 mL of the metal solution. A study on the adsorption kinetics and isotherms was performed applying the optimized conditions. The adsorption process followed a pseudo-second-order model. The experimental adsorption data were fitted to the Langmuir and Freundlich isotherm adsorptions and a very good fit to the Langmuir linear model was observed. The maximum adsorption capacity was found to be 35.52 mg g-1.
Highlights
The presence of toxic metals in aqueous systems due to discharges from various industrial processes has caused serious environmental problems, due to their non-biodegradability and ability to accumulate in living tissues.[1]Lead is one of the most toxic of the metal ions, even in low concentrations, and exposure can lead to a wide range of adverse health effects in both adults and children
Infrared spectroscopy is an important tool in the identification of the functional groups that may be present in different substances
With increasing pH protons are probably removed from the surface of the adsorbent material releasing active sites which can be occupied by metal ions
Summary
The presence of toxic metals in aqueous systems due to discharges from various industrial processes has caused serious environmental problems, due to their non-biodegradability and ability to accumulate in living tissues.[1]Lead is one of the most toxic of the metal ions, even in low concentrations, and exposure can lead to a wide range of adverse health effects in both adults and children. Adsorption experiments were carried out using various initial PbII concentrations and optimum conditions of adsorbent dosage, contact time and pH.
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