الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 286 |  |  |
| | | from | 286 | | |
Abstract
An ion imprinted polymer for Ni(II) was synthesized by the trapping method and bulk polymerization based on dimethyl glyoxime as a chelating ligand [(Ni(II)-(DMG)2),IIP]. The structures and the properties of the ion imprinted and non-imprinted polymers were explored using various physicochemical characterization techniques. These included, Fourier transform Infra-Red spectroscopy (FTIR), scanning electron microscopy (SEM).
The [(Ni(II)-(DMG)2),IIP] with optimized molar ratio of monomer to cross-linker to 2,2’-azobisisobutyronitrile (AIBN) initiator to porogen and template to ligand was studied for effects of pH, mass, contact time to uniformly design an experimental method. The optimum parameters were: IIP mass, 50 mg; pH, 9.0; and contact time, 10 min. The best ratios of cross-linker to monomer, monomer to template and (NiSO4.6H2O) to 4-vinylpyridine (4-VP) to dimethylglyoxime (DMG) were: 3.3:1.0, 0.6:1.0, and 1.0:2.0:4.0, respectively. The optimum amounts of porogen and initiator were 10 ml and 40 mg, respectively. During this optimization, the recovery rate of Ni(II) is increased to reach 100%. The selectivity of the prepared ion imprinted polymer was evaluated by using inductively coupled plasma-optical emission spectrometer to analyze Ni(II) ions alone and in combination with different concentrations of Co(II), Cu(II), Zn(II), Pd(II), Fe(II), Ca(II), Mg(II), Na(I) and K(I) ions in aqueous samples. The selectivity study also confirmed that the ion imprinted polymer has very good selectivity, which is characterized by low % RSD of less than 5 %. However, Co(II) was the only ion that can slightly interfere with the determination of Ni(II), due to its high affinity to the DMG chelating ligand. The quantification limit and detection limit were 0.9 and 0.3 ng/mL, respectively. The proposed method was evaluated by analyzing a customized solution of ground water certified reference material (SEP-3) and sandy soil reference material (BCR-142R), where the obtained Ni(II) concentration were in excellent agreement with the certified reference values. Then the [(Ni(II)-(DMG)2),IIP] was applied to the assessment of Ni(II) from real soil and water samples, and the recoveries were 93-100 % and 98-101 %, respectively. The enrichment factors in the water and soil samples were 2-16.6, and 27.6-36.6, respectively.
In addition, an IIP of Hg(II) was synthesized by copolymerizing functional and cross-linking monomers, N’- [3-(Trimethoxysilyl)-Propyl]diethylenetriamine (TPET) and tetraethylorthosilicate (TEOS), in the presence of mercury(II) ions as template. In this synthesis, cetyltrimethylammonium bromide (CTAB) was used as second template to boost the efficiency of the polymer. The imprinted polymer particles were characterized by FTIR, SEM, and their average size was specified by screen analysis using a standard sieve test. The relative selectivity coefficients (k`) of imprinted polymers were estimated based on the selective binding study between Hg2+ and Cd2+ or Cu2+ ions and were found to be 3146 and 10588, respectively. These values indicated that the extraction of Hg2+ is better than that of the two most competing ions. The polymer’s application to several fresh water samples resulted in significant extraction efficiency (EEs) of Hg2+ ions; (in all cases above 84%), as measured by ICP-OES. The LOD was found to be 0.036 ng /ml and the % RSD was less than 4%. These findings suggest that the current double-imprinted polymer could be efficiently used to selectively pre-concentrate mercury(II) ions from complex aqueous environments.