Direct bromination of nano hydroxyapatite strategy towards particle brushes via surface-initiated ATRP for highly efficient heavy metal removal

Aminated n-HAP-g-polyacrylonitrile (n-HAP-g-APAN) particle brushes were developed for highly efficient heavy metal removal based on surface-initiated ATRP (SI-ATRP) and subsequent amination. An efficient one-step method for morphology controlled synthesis of ATRP initiator immobilized n-HAP (n-HAP-Br) was realized by using 2-bromoisobutyric acid as tetherable initiator. Uniform and individually dispersed n-HAP-Br NCs were obtained with controlled morphology and particle size by adding portion of water miscible organic solvents to rational adjusting aqueous dispersion medium. Aminated n-HAP-g-APAN displayed record-high adsorption capacity of heavy meatal ions due to the combined contributions of grafted APAN providing pendent amino diethylenepentamine as chelating groups and n-HAP core towards heavy metal ions (pure n-HAP of q e  = 284.4 mg/g vs n-HAP-g-APAN of q e  = 944.4 mg/g). The proposed one-step direct bromination of n-HAP strategy provides the preparation of uniform n-HAP NCs ready for polymer grafting and further fabrication of n-HAP-g-polymers via SI-ATRP for various applications depending on the characteristic of grafted polymers.