Abstract
Abstract Magnetic nanopowders were developed by functionalization of bimagnetic core@shell nanoparticles with cysteine (CoFe2O4@ɣ-Fe2O3@Cys), which present a core with high saturation magnetization (CoFe2O4) combined with a shell with high long-term chemical stability (ɣ-Fe2O3) and a sorptive L-cysteine layer. Samples of two different mean sizes were elaborated and characterized by XRD, TEM, FTIR, SER, zetametry and SQUID magnetometry. The adsorption of Pb(II) by the magnetic nanopowders was investigated as a function of pH, time, and pollutant concentration. The Langmuir model fitted well the adsorption data indicating monolayer adsorption, and a maximum adsorption capacity of 1.2 mg/g was found for pH 5. The kinetic data were well correlated to the pseudo-second-order model and the best equilibrium time was 120 min. The adsorption mechanism mainly involves electrostatic interactions in pH 5-7 and hard–soft-acid–base interactions in low pH. Moreover, the nanoparticles were recovered and reused in readsorption experiments keeping a good removal efficiency.
Highlights
Due to the great importance of potable water for the maintenance of life and its gradually scarce availability, the spread of contaminants in water bodies has become an increasingly serious problem
Recent research indicates that the surface of magnetic nanoparticles (NPs) can be coated with different binders, increasing the adsorption capacity depending on the target pollutant[9,22,23]
The present study reported on the synthesis of cysteineferrite-based magnetic nanopowders of two different mean sizes and their application for Pb(II) removal from water
Summary
Due to the great importance of potable water for the maintenance of life and its gradually scarce availability, the spread of contaminants in water bodies has become an increasingly serious problem. Some usual technologies are based on chemical precipitation[10], ionic exchange[11,12], membrane filtration[13], electrolytic methods[14], reverse osmosis[15], and solvent extraction[16] Most of these methods have disadvantages due to limitations in the pH range since they use the reduction of metal ions as the main mechanism of action[17], as well as the high cost, difficulty of operation and significant energy consumption[18]. L-cysteine is a very promising choice because it contains sulfur, which has a strong tendency to coordinate with lead cation forms[26]
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