Surface Modification of Crosslinked Chitosan Beads Via Atom Transfer Radical Polymerization Technology for Effective Boron Removal: A Combined FTIR, XPS, and Quantum Modeling Study

As boron in water has potential adverse effect on plant species, it must be treated for irrigation utilization. In this study, a new approach was developed for preparation of an adsorbent with high boron sorption capacity, by surface modification of crosslinked chitosan beads via atom transfer radical polymerization. 2-bromoisobutyrate bromide as an initiator was first immobilized on the surface of CCTS through the interactions with hydroxyl and amine groups. Glycidyl methacrylate (GMA) polymer brushes were grafted from the surface-initiated chitosan by the ATRP. Epoxides of the grafted poly(glycidyl methacrylate) (PGMA) further reacted with N-methyl glucamine (NMDG) to obtain the sorbent (CTS-MG) for boron sorption. The morphological study of sorbents by optical and scanning electron microscopy showed that the chemical modification contributed to significant changes in both particle size and surface morphology. Fourier transform infrared and X-ray Photoelectron spectroscope analyses demonstrated that the oxygen in the form of secondary alcohol played an important role in boron sorption, and the tetrahedral boron complexes were present on the surface of the sorbent. Quantum modeling tool was used to illustrate the uptake of boron from aqueous solution.