Mechanistic links between magnetic nanoparticles and recovery potential and enhanced capacity for crystal violet of nanoparticles-coated kaolin

Kaolin has potential in wastewaters treatment due to its advantage of nontoxicity to aquatic flora and fauna. However, its adsorption capacity needs significant improvement, in addition, the re-collection of adsorbents after application can reduce the risk of desorption of pollutants. Therefore, nanoparticle-modified kaolin (NMK) was prepared by coating kaolin with Fe 3 O 4 nanoparticles to enhance the adsorption capacity of kaolin for crystal violet (CV) in this study. Fe 3 O 4 nanoparticles improved the adsorption capacity of kaolin by at least an order of magnitude, with a maximum capacity of 247.68 ± 4.56 mg CV/g NMK with the initial CV concentration of 800 mg/L; additionally, nanoparticles endowed NMK a magnetization of 21.20 emu/g, indicating that NMK has a magnetic re-collection potential. Spectroscopic analysis demonstrates that the epoxy groups in kaolin are likely the link to the nanoparticles, and the aromatic C C and C O groups of NMK could be responsible for CV adsorption. The enhanced adsorption capacity mechanism of NMK is attributed to nanoparticles decreased zeta potential and changed porous surface characteristics of virgin kaolin. The results suggest that some materials can become more effective in environmental applications via modification by nanoparticles.