Magnetic adsorbent of Fe 3 O 4 @SiO 2 core shell nanoparticles modified with thiol group for chloroauric ion adsorption
Abstract The magnetic adsorbent of Fe 3 O 4 @SiO 2 core shell nanoparticles modified with thiol group was synthesized for chloroauric [AuCl 4 adsorption. The Fe 3 O 4 nanoparticles were prepared by co precipitation method under mechanical stirring and coated with SiO 2 by acid hydrolysis of Na 2 SiO 3 under N 2 purging. The coating of Fe 3 O 4 nanoparticles with SiO 2 prevents particles' agglomeration by forming Fe 3 O 4 Fe 3 O 4 Fe 3 O 4 @SiO 2 core shell and avoids dissolution of the Fe 3 O 4 core in the acidic medium. The coated Fe 3 O 4 particle was modified with a thiol group using 3 mercaptopropyltrimethoxysilane via silanization reaction. The results suggest that SiO 2 coated Fe 3 O 4 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 [AuCl 4 ion adsorption by the Fe 3 O 4 @SiO 2 core shell nanoparticles followed Langmuir isotherm model with a maximum adsorption capacity of 115 mg/g and free energy (DGdeg) of 24.8 kJ/mol. The thiourea solution can be used to desorb most of the adsorbed [AuCl 4 ion. The adsorption using magnetic compounds provides easy access to the separation for both preparation and recovery.