Adsorption Capacity Of Ion-imprinted Polymer Research Articles

Palladium ion-imprinted polymers with PHEMA polymer brushes: Role of grafting polymerization degree in anti-interference

Ion-imprinted polymers (IIPs) exhibit great potential as the adsorbent for adsorption of palladium from the industrial wastewater. However, co-existence of complicated water matrixes can readily block the imprinting cavities and disturb the adsorption of target ions. Therefore, it is meaningful to endow the IIPs with an excellent anti-interference ability toward practical applications. In this work, the polymer 2-hydroxyethyl methacylate (PHEMA) polymer brushes with different polymerization degree were successfully grafted on the IIPs. The polymerization degrees of PHEMA brushes are 43, 49, 73, 122, and 294 for the IIP-1, IIP-2, IIP-3, IIP-4, and IIP-5, respectively. Batch experiments reveal that polymerization degree has an inconspicuous effect on the adsorption capacity of IIPs. And their adsorption capacities are in the range from 42 to 46 mg/g, which is much higher than most adsorbents documented in literature. The kinetic constant has increased from 0.021 to 0.042 g/(mg·min) with the increase of polymerization degree from 43 to 294, respectively. This result implies that the high-polymerization PHEMA brush can accelerate the adsorption of Pd. More importantly, the anti-interference ability of IIP-3 significantly outperforms the ungrafted IIPs; and corresponding anti-interference mechanism has been proposed. This work provides a fundamental insight into the inter-relation between polymerization degree of polymer brushes and its anti-interference ability, which may facilitate the IIPs-based technology for the adsorption and recovery of valuable metals from complex wastewater.

Selective Ce(III) ion-imprinted polymer grafted on Fe3O4 nanoparticles supported by SBA-15 mesopores microreactor via surface-initiated RAFT polymerization

Ce(III) ion-imprinted polymer (Ce(III)-IIP) grafted on Fe3O4 nanoparticles supported by SBA-15 mesopores microreactor was successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization for selective removal of Ce(III) from aqueous solution. The characterization results suggest that the surface ion-imprinted polymer (IIP) synthesized by RAFT is a thin layer. Adsorption isotherm experiments indicated that Redlich-Peterson isotherm model best fitted the experimental data and the adsorption capacity of IIP was obviously higher than that of non-imprinted polymers (NIP) at the same conditions. The kinetics of adsorption followed the Thomas model. Moreover, competitive adsorption studies illustrated that Ce(III)-IIP offers the advantages of selectivity towards Ce(III) compared with NIP even in the presence of other metal ions. All above results indicated the potential application of Ce(III)-IIP for selective removal of Ce(III) from aqueous solution.

Highly selective solid phase extraction of mercury ion based on novel ion imprinted polymer and its application to water and fish samples

A novel ion imprinted polymer (IIP) material has been synthesized for mercury ion. The IIP material is applied to the solid phase extraction (SPE) of Hg2+ from complex matrixes including water and fish samples. The IIP-SPE method is operated prior to cold vapor atomic absorption spectroscopy (CV-AAS) to determine mercury ion. In the polymer synthesis, mercury ion, 2-vinylpyridine, ethyleneglycol dimethacrylate and 2,2′-azobisisobutyronitrile are used as target, Hg2+ complexing reagent monomer, cross-linker and initiator, respectively. The polymer is characterized on the basis of FT-IR and thermal analysis (thermogravimetric, TGA; differential thermic, DTA; and differential scanning calorimetry, DSC). The obtained polymer block is ground, sieved and Hg2+ ions are removed from polymer particles by leaching with EDTA, which leaves a cavity in the polymer particles. The maximum Hg2+ adsorption capacity of IIP is 24.6 mg/g. Effective parameters on retaining Hg2+ such as pH, flow rate of sample and eluent, nature of the eluent, ionic strength, selectivity coefficient and retention capacity are investigated. The detection limit and the relative standard deviation are 5 × 10−4 ng/mL and 2.4%, respectively. After 20 adsorption cycles, the recovery of Hg2+ on IIP is only decreased by 3.2%. The column selective adsorption experiments of Na+, Cu2+, Pb2+, Cd2+, Ca2+ and Mg2+ ions with respect to mercury are conducted by using imprinted and non-imprinted polymer. These results showed that the IIP is highly selective for Hg2+ over the other metals.

An imprinted polymer for removal of Cd2+ from water samples: Optimization of adsorption and recovery steps by experimental design

A new ion-imprinted polymer (IIP) was synthesized by copolymerization of 4-vinylpyridine (monomer), ethyleneglycoldimethacrylate (cross-linker) and 2,2-azobis-isobutyronitrile (initiator) in the presence of Cd2+ and quinaldic acid (complexing agent). It was found that the adsorption capacity of IIP and blank polymer were 45.0 and 6.2 mg g−1, respectively. The relative selectivity coefficients of the imprinted polymer for different binary mixture were also calculated. Compared to non-imprinted polymer (NIP), the IIP had higher selectivity for Cd(II). The IIP was used as a sorbent for cadmium extraction from water samples by using a simple batch extraction procedure. The effect of different parameters on Cd2+ extraction and its recovery from the IIP were evaluated and optimized by using experimental design methodology. The optimized adsorption/desorption procedure was applied for cadmium removal from the real water samples. The obtained recoveries proved that this IIP could be used for removal of trace cadmium ions from water samples.

Synthesis, characterization and analytical applications of Ni(II)-ion imprinted polymer

Ion recognition-based separation techniques have received much attention because of their high selectivity for target ions. In this study, we have prepared a novel ion imprinted polymer (IIP) to remove nickel ions with high selectivity. The imprinted polymer was prepared by copolymerization of 2-hydroxy ethyl methacrylate (HEMA) with nickel vinylbenzoate complex in the presence of ethylene glycol dimethacrylate (EGDMA) as a crosslinker. The polymerization was carried out in bulk with free radical initiation using 2-methoxy ethanol as a solvent and porogen. The adsorbed nickel was completely eluted with 15 mL of 1 M HCl. Control polymer was also prepared by similar experimental conditions without using imprint ion. The above synthesized polymers were characterized by surface area measurements, FT-IR, microanalysis and SEM analysis. The adsorption capacity of IIP and CP was found to be 1.51 and 0.65 mmol g −1, respectively. The optimal pH for quantitative enrichment was 6.5. Nature of eluent, eluent concentration and eluent volume were also studied. The relative selectivity factor ( α r) values of Ni(II)/Zn(II), Ni(II)/Cu(II) and Ni(II)/Co(II) were 78.6, 111.1 and 91.6, respectively. Five replicate determinations of 30 μg L −1 of Ni(II) gave a mean absorbance of 0.067 with a relative standard deviation of 1.06%. The lowest concentration determined by GTA-AAS below which the recovery becomes non-quantitative is 6 μg L −1. IIP was tested for removal of Ni(II) from sea water sample.

Synthesis, characterization and removal of Cd(II) using Cd(II)-ion imprinted polymer

A novel ion imprinted polymer (IIP), phenol–formaldehyde–Cd(II)–2-( p-sulphophenylazo)-1,8-dihydroxynaphthalene-3,6-disulphonate (PF–Cd(II)–SPANDS) has been synthesized for selective solid phase extraction (SPE) of Cd(II) from aqueous solutions. IIP was prepared by the copolymerization of phenol and formaldehyde in the presence of Cd(II)–SPANDS complex in acidic medium. This polymer has been characterized on the basis of FTIR, elemental analysis and surface area measurement. Subsequently, the imprinted Cd(II) was completely removed by leaching the dried and powdered imprinted polymer with 1 M HNO 3 or 0.01 M EDTA in 0.5 M HNO 3. Adsorption capacity was determined by batch experiments for Cd(II), Zn(II), Cu(II) and Hg(II) ions. The effect of pH, flow rate and equilibrium adsorption time was also studied for Cd(II). Adsorption equilibrium time was 50 min. The maximum adsorption of Cd(II) ions on to the imprinted polymer was 270 μg g −1. For comparison, the adsorption of metal ions was also studied on non-imprinted polymer (NIP). The adsorption capacity of IIP was found 59.2% higher than that of NIP for Cd(II) ion. However, for other investigated transition metal ions the capacity difference was not significant. The relative selectivity factor ( α r) values of Cd(II)/Zn(II), Cd(II)/Cu(II) and Cd(II)/Hg(II) are 7.4, 6.6 and 6.7, respectively which are greater than 1.