In the present work, a novel two-dimensional (2D) nickel ion-imprinted polymer (RAFT-IIP) has been successfully synthesized based on the graphene oxide/SiO2 composite by reversible addition–fragmentation chain-transfer (RAFT) polymerization. The imprinted materials obtained are characterized by Fourier transmission infrared spectrometry (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results show that the thermal stability of the graphene oxide/SiO2 composite is obviously higher than that of graphene oxide. RAFT-IIP possesses an excellent 2D homogeneous imprinted polymer layer, which is a well-preserved unique structure of graphene oxide/SiO2. Owing to the intrinsic advantages of RAFT polymerization and 2D imprinted material, RAFT-IIP demonstrate a superior specific adsorption capacity (81.73 mg/g) and faster adsorption kinetics (30 min) for Ni(II) in comparison to the ion-imprinted polymer prepared by traditional radical polymerization and based on the common carbon material. Furthermore, the adsorption isotherm and selectivity toward Ni(II) onto RAFT-IIP and nonimprinted polymer (NIP) are investigated, indicating that RAFT-IIP has splendid recognizing ability and a nearly 3 times larger adsorption capacity than that of NIP (30.94 mg/g). Moreover, a three-level Box-Behnken experimental design with three factors combining the response surface method is utilized to optimize the desorption process. The optimal conditions for the desorption of Ni(II) from RAFT-IIP are as follows: an HCl-type eluent, an eluent concentration of 2.0 mol/L, and an eluent volume of 10 mL.

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.

In this work, novel core–shell ion imprinted polymers were firstly synthesized by photoinitiated polymerization (P-IIPs) for the selective separation of Co(II) in aqueous solution. In contrast to thermal polymerization, photoinitiated polymerization exhibits faster initiation rate, only a quarter of the former, and can be performed at room temperature. Subsequently, extensive characterizations were performed using FT-IR, SEM, TEM, XRD, and TGA. Adsorption isotherm and kinetics studies were carried out in batch adsorption experiments. Furthermore, the removal of Co(II) from aqueous solution was investigated at different conditions by using P-IIPs as the adsorbent in the fixed-bed column and the parameters were discussed and optimized. The data can be well fitted by the Thomas model, offering some model parameters for process design. Compared with non-imprinted polymers, P-IIPs displayed remarkable selectivity toward Co(II). Moreover, the synthesized polymers possessed excellent desorption performance and regeneration property with a desorption efficiency up to 94.1%. P-IIPs enabled the selective extraction of Co(II) successfully from sediment samples with satisfactory recovery. The above mentioned results indicate that P-IIPs are promising high-performance, low-energy and environmentally friendly adsorbents for effectively removing Co(II) from aqueous solution.

In this work, two novel Cs(I) ion-imprinted polymers (Cs(I)-IIP1 and Cs(I)-IIP2) have been prepared by surface imprinting technique based on support matrix of SBA-15. The strategy was carried out by introducing two different reversible addition–fragmentation chain transfer (RAFT) polymerization including using the free RAFT agent in solution and surface-anchored RAFT agent with appropriate initiation method, which is expected to generate a well-defined surface ion-imprinted polymer with excellent adsorption capacity. The materials were verified by FT-IR, SEM, TEM, nitrogen adsorption–desorption and TGA. Owing to the intrinsic advantages of surface-anchored RAFT polymerization, the resultant surface ion-imprinted polymer (Cs(I)-IIP2) exhibited more homogeneous and thinner polymer layer (15 nm) with excellent macrostructure in comparison to Cs(I)-IIP1 (75 nm) prepared by using the free RAFT agent in solution. Furthermore, the adsorption capacity of both polymers are compared, indicating that Cs(I)-IIP2 displays higher adsorption property and excellent selectivity for Cs(I).

A surface-imprinted mesoporous sorbent for Pb(II) ion was synthesized by the post-synthesis method. The material was characterized by transmission electron microscopy and nitrogen adsorption-desorption isotherms. The adsorption by the material was studied by batch experiments with respect to effects of pH value, contact time, kinetics, and adsorption isotherms. Both the pseudo-second-order kinetic model and the Langmuir model fit the experimental data well. Compared to other imprints for Pb(II), to the traditional sorbents and to the non-imprinted polymer, the new sorbent displays fast kinetics and higher selectivity. Pb(II) ion can be desorbed from the imprint with 2 M hydrochloric acid with high efficiency. The sorbent was applied to the selective separation and determination of Pb(II) in water and sediment samples with satisfactory results.

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.