Abstract
Lead ion in drinking water is one of the most dangerous metals. It affects several systems, such as the nervous, gastrointestinal, reproductive, renal, and cardiovascular systems. Adsorption process is used as a technology that can solve this problem through suitable composites. The adsorption of lead (Pb(II)) on graphene oxide (GO) and on two goethite (α-FeOOH)/reduced graphene oxide (rGO) composites (composite 1: 0.10 g GO: 22.22 g α-FeOOH and composite 2: 0.10 g GO: 5.56 g α-FeOOH), in aqueous medium, was studied. The GO was synthesized from a commercial pencil lead. Composites 1 and 2 were prepared from GO and ferrous sulfate. The GO and both composites were characterized by using scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), Raman spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The adsorption capacity of Pb(II) on the GO and both composites was evaluated through adsorption isotherms. Composite 1 presented a significant agglomeration of α-FeOOH nanorods on the reduced graphene oxide layers. Meanwhile, composite 2 exhibited a more uniform distribution of nanorods. The adsorption of Pb(II) on the three adsorbents fits the Langmuir isotherm, with an adsorption capacity of 277.78 mg/g for composite 2200 mg/g for GO and 138.89 mg/g for composite 1. Composite 2 emerged as a highly efficient alternative to purify water contaminated with Pb(II).
Highlights
Heavy metals have been the major pollutants in the last decades, around the world
graphene oxide (GO) is an alternative that has been recently tested for the removal of heavy metals, and with good results [5]
The composites synthesis was previously reported by Xu et al [11]; they obtained four composites with different mass ratios, but, for this work, they chose the two most different mass ratios reported, in order to better understand each component’s contribution to the lead adsorption process
Summary
Heavy metals have been the major pollutants in the last decades, around the world. Due to their persistence, bioaccumulation, biomagnification, and toxicity, they represent a threat to aquatic life, and especially to human health [1]. In recent years, efforts to find alternative adsorbents have increased Due to their low cost and wide availability, natural materials such as clays and metal oxides are being studied in more detail [4]. Its functional groups (hydroxyl, carboxyl, and epoxide) allow it to participate in many interactions This material can be used as a substrate for the growth of metal oxides and hydroxides, improving its adsorbent properties [6]. Goethite (α-FeOOH) is one of the most studied iron oxyhydroxides It is a mesoporous material with high potential for the adsorption of contaminants, due to its low solubility and easy laboratory synthesis [7]. It is important to emphasize that the results can be extrapolated for the adsorption of other heavy metals
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