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Conference information: Abstracts, 15th Iranian Chemistry Congress

Abstract: Thallium is a heavy metallic element which exists in environment mainly combined with other elements (primarily oxygen, sulfur and the halogens) in inorganic compounds. Thallium can be found in nature as Tl (I) and Tl (III) ions but its monovalent state has higher stability, whereas its trivalent state forms complexes of greater stability. Each oxidation state of the element exhibits different bioavailability and toxicity property [1] and hence thallium speciation in environment is important. As the total concentration of thallium in aquatic environment is very low, an analytical technique featuring high sensitivity and low detection limit is required [2].During the last years ion-imprinted polymers (IIPs), as selective sorbents for a particular chemical form of the given element, have received much attention. The high selectivity of IIPs can be explained by the polymer memory effects towards the metal ion interaction with a specific ligand, coordination geometry, metal ion coordination number, charge and size [3].In this study, a thallium (I) ion-imprinted polymer as a new sorbent has been synthesized for the first time. This sorbent was used for SPE and preconcentration of Tl (I) ions from aqueous solutions.Thallium (I) ion-imprinted polymer (IIP) particles were synthesized by preparing the ternary complex of thallium (I) ions with 5, 7-dichloroquinoline-8-ol (DCQ) and 4-vinylpyridine (VP). Thermal copolymerization with methyl methacrylate (functional monomer, MMA) and ethyleneglycoldimethacrylate (cross-linking monomer, EGDMA) was then performed in the presence of acetonitrile (porogen) and 2, 2 -azobisisobutyronitrile (initiator, AIBN). The imprinted ion was removed from polymer by stirring of the above particles with 1M HNO3 to obtain the leached IIP particles. Moreover, control polymer (CP) particles were similarly prepared without the thallium (I) ions. The unleached and leached IIP particles were characterized by surface area analysis (BET), X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR) and scanning electron microscopy (SEM).The preconcentration of the thallium (I) traces was studied during rebinding with the leached IIP particles as a function of pH, the weight of the polymer material, the preconcentration and the uptake times, the uptake volume and the aqueous phase volume. Electrothermal atomic absorption spectrometry (ETAAS) was employed for determination of thallium in aqueous solution. The limit for detection of the method was 0.02ngmL??1, while the relative standard deviation for five replicates was 2.5%
Template and target information: thallium ion, Tl(I)