Synthesis of hydrophilic surface ion-imprinted polymer based on graphene oxide for removal of strontium from aqueous solution

A novel hydrophilic ion-imprinted polymer based on graphene oxide has been synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization with surface imprinting technique. Methylacrylic acid is used as a hydrophilic functional monomer. The resultant adsorbent is verified by UV-vis scanning spectrophotometer, Fourier transmission infrared spectrometry, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction, water contact angle measurements, and thermogravimetric analysis. The results suggest that the surface imprinted polymer synthesized by RAFT is a homogeneous thin layer. Owing to the intrinsic advantages of controlling/living polymerization and surface imprinting technology, the obtained RAFT surface ion-imprinted polymer (RAFT-IIP) exhibits excellent imprinting efficiency and adsorption capacity in comparison to the ion-imprinted polymer prepared by traditional radical polymerization. Furthermore, the adsorption isotherm and recognizing ability towards Sr(II) onto RAFT-IIP and non-imprinted polymer (NIP) are compared in batch experiments. The equilibrium data are well fitted by Langmuir model and RAFT-IIP has higher selectivity and nearly four times larger Langmuir calculated maximum adsorption capacity (145.77 mg g−1) than that of NIP at 25 °C. Meanwhile, RAFT-IIP is regenerated and found to be suitable for reuse in successive adsorption–desorption cycles five times without significant loss in adsorption capacity.