Abstract
In the present article, the adsorbent prepared from laterite with lanthanum and cerium oxides (La2O3-CeO2/laterite (LCL)) was efficiently employed for the removal of arsenite and fluoride from an aqueous environment. The obtained materials were characterized by XRD, SEM, and nitrogen adsorption/desorption. The synthesized LCL exhibited a high adsorption capacity towards arsenite (As(III)) and fluoride. The adsorption of both analytes on LCL, which was well-fitted to a pseudo-second-order equation, was found to be kinetically fast in the first 20 minutes and reached equilibrium at around 180 minutes. Weber’s intraparticle diffusion model in multilinearity using the piecewise linear regression combined with Akaike’s criteria was addressed. The adsorption capacities of LCL calculated from Langmuir’s isotherm model were found to be 67.08 mg·g-1 for arsenite and 58.02 mg·g-1 for fluoride. Thermodynamic parameters presented an endothermic nature of arsenite adsorption but an exothermic nature for fluoride and a negative Gibbs free energy for the spontaneous process of arsenite or fluoride adsorption at the studied temperature range. The excellent adsorption performance and stability make the composite of laterite and La-Ce binary oxides an alternative efficient and cheap adsorbent for the removal of arsenite and fluoride in an aqueous solution.
Highlights
Arsenic or fluoride-contaminated water is an environmental problem which can lead to severe human health implications and ecological concern [1, 2]
As can be seen from Figure, three distinct weight losses according to three exothermic process peaks at 192°C, 281°C, and 476°C are observed
0.965 0.980 implying that the line does not pass the origin [38]. These results reveal that the intraparticle diffusion is not the only rate-limiting process
Summary
Arsenic or fluoride-contaminated water is an environmental problem which can lead to severe human health implications and ecological concern [1, 2]. Synthesized nanosized adsorbents including La2O3, Fe3O4, CeO2, CuO, MnO2, and TiO2, which exhibited a potential ability to remove arsenic or fluoride from an aqueous environment, have been extensively studied [25,26,27]. Their improved adsorption could be attributed to their controllable surface properties, being suitable for arsenite and fluoride removal. The composite of low-cost natural laterite and La-Ce bimetal oxides (LCL) is explored as a potential fluoride and arsenic adsorbent. The Langmuir and Freundlich isotherms were addressed, and the thermodynamic calculations were performed to have more insight into the process
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