Particle-Assisted Ion-Imprinted Cryogels for Selective Cd^IIIon Removal

Abstract

Herein, we have reported particle-assisted ion-imprinted cryogels, which were synthesized by embedding finely crushed functional particles into cryogel structure under semifrozen conditions. These cryogels showed high adsorption efficiency and affinity against Cd II ions. Cd II adsorption performances were evaluated by varying some effective factors. In order to analyze the data, we applied Langmuir and Freundlich adsorption isotherms while using three different kinetic models, pseudo-first-order, pseudo-second-order, and Weber−Morris as well. Also, the dimensionless equilibrium parameter (R L ), initial adsorption rate, and half-adsorption time were calculated. The results revealed that ion-imprinted-polymer (IIP) cryogels have homogeneously distributed cavities, which were formed by a particle-assisted imprinting process, and the theoretical maximum adsorption capacity (Q max , 35.97 μg/g) was very close to the experimental value (Q eq , 32.15 μg/g). In addition, R L values for both IIP and nonimprinted-polymer cryogels showed favorability of the adsorption process, while kinetic models indicated that there were no diffusion limitations during the adsorption process, which means that the rate-limiting step was chemosorption of heavy-metal ions on binding sites (imprinted cavities or functional groups) with a high initial adsorption rate and a low half-adsorption time. Desorption, reusability, and selectivity studies were also conducted to state the performance of the cryogels. In conclusion, this promising approach provides a novel methodology for selective Cd II removal from water sources.

Specific heavy metal ion recovery with ion‐imprinted cryogels

“…Tabaklı et al . developed Cd(II)‐imprinted cryogels through particles assisted imprinting approach and reported maximum adsorption capacity as 0.0322 mg/g (32.15 μg/g) cryogel . As a result, the capacity values reported in this study are comparable to or higher than the values reported in literature.…”

Molecularly imprinted smart cryogels for selective nickel recognition in aqueous solutions

“…Nevertheless, NIP cryogel was lack of self‐assembled specific binding sites complementary to template ions. The difference in adsorption capacity of MIP and NIP cryogels made this newly synthesized cryogel a promising adsorbent as an important alternative among the traditional materials that possessed high efficiency for removal of metal ions 36 . In comparison to the literature, there were many reports about nickel ion imprinted adsorbents, which emphasized the importance of the removal of nickel ions from aqueous solutions.…”

“…The difference in adsorption capacity of MIP and NIP cryogels made this newly synthesized cryogel a promising adsorbent as an important alternative among the traditional materials that possessed high efficiency for removal of metal ions. 36 In comparison to the literature, there were many reports about nickel ion imprinted adsorbents, which emphasized the importance of the removal of nickel ions from aqueous solutions. Among these, Ersöz et al prepared Ni(II) imprinted beads using MAH as the functional monomer and ethyleneglycoldimethacrylate as the cross-linker.…”

Model fitting of sorption kinetics data: Misapplications overlooked and their rectifications

“…Later, the Lagergren model was extended to describing the adsorption kinetics of divalent heavy metals by Ho et al, which became the pseudosecond‐order rate equation that is widely used at present. Compared to Lagergren's pseudofirst‐order model, the pseudosecond‐order rate model appears to fit the kinetic data better for a broader range of adsorption systems …”

“…Compared to Lagergren's pseudofirst-order model, the pseudosecond-order rate model appears to fit the kinetic data better for a broader range of adsorption systems. [15][16][17] The pseudosecond-order rate model as represented by a semiempirical equation is actually a "lumped" form of more complicated theoretical representations. 18,19 The adsorption rate at a given time is considered to be determined by the difference between the sorption amount (Q t ) at the time and the maximum sorption amount if the system would reach equilibrium (Q e ), that is, (Q e -Q t ).…”