Add time:08/10/2019         Source:sciencedirect.com

The magnetic adsorbent of Fe3O4@SiO2 core-shell nanoparticles modified with thiol group was synthesized for chloroauric ([AuCl4]−) adsorption. The Fe3O4 nanoparticles were prepared by co-precipitation method under mechanical stirring and coated with SiO2 by acid hydrolysis of Na2SiO3 under N2 purging. The coating of Fe3O4 nanoparticles with SiO2 prevents particles’ agglomeration by forming Fe3O4 Fe3O4 Fe3O4@SiO2 core-shell and avoids dissolution of the Fe3O4 core in the acidic medium. The coated Fe3O4 particle was modified with a thiol group using 3-mercaptopropyltrimethoxysilane via silanization reaction. The results suggest that SiO2-coated Fe3O4 particles have a size of 10–20 nm. The FTIR and EDX data indicate that the thiol groups are successfully attached to the surface of the nanoparticles. The [AuCl4]− ion adsorption by the Fe3O4@SiO2 core-shell nanoparticles followed Langmuir isotherm model with a maximum adsorption capacity of 115 mg/g and free energy (ΔG°) of 24.8 kJ/mol. The thiourea solution can be used to desorb most of the adsorbed [AuCl4]− ion. The adsorption using magnetic compounds provides easy access to the separation for both preparation and recovery.

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