Synthesis and characteristics of chelating fibers containing imidazoline group or thioamide group

Abstract

Two types of chelating fibers containing an imidazoline or thioamide group were prepared through the functionalization of hydrazine-modified polyacrylonitrile fiber by ethylenediamine and through the amination and sulfurization reaction of the hydrazine-modified polyacrylonitrile fiber under appropriate conditions, respectively. It is shown that the reaction temperature, time, and agent concentration are the dominant factors in the synthesis of fibrous sorbents. The increase of the ethylenediamine concentration from 33 to 45% (v/v) at 95-98°C results in a twofold higher increase of the fibrous sorbent with the imidazoline group, and a doubling of the reaction time from 2 to 4 h leads to a weight increase of the fibrous sorbent from 10 to 25% (w/w). Raising the temperature by about 5°C significantly accelerates the amination reaction of the hydrazine-modified fiber, but the temperature is an insensitive factor in the thioamidefunctionalized reaction of the aminated fiber. The introduction of a thioamide or imidazoline group is further verified by IR spectroscopy analysis. X-ray diffraction spectroscopy indicates the absolute disappearance of crystalline peaks for the fibers containing an imidazoline or thioamide group. However, the crosslinking reaction of the polyacrylonitrile fiber by hydrazine may make up for the effect of the crystallinity on the mechanical strength of the fibers, and the surface crackles of fibrous sorbents are not found by SEM photographs. The adsorption experiment results show that the newly prepared sorbents have high sorption capacities for noble metals in a high acidity, and it is also proved that Au(III) loaded on the chelating fibers may be reduced to Au(0).

Cancer statistics, 2011

“…In particular, chelating polymers of fibrous types have come into the spotlight because of advantages including the ability to be fabricated in the form of felts of fabrics, which display improved contact efficiencies with the media 3. Many scientists and engineers are therefore interested in developing these materials 4, 5. Despite that, the equilibrium study of anion particles adsorption on a chelating fiber is still far from the real application because of the difficulty of describing chain motions of a polymer and uncertain ion concentration distribution in solution.…”

Effect of polymer backbone chemical structure on metal ions binding by imidazolylmethyl derivatives

“…Formation of gold particles was also found after sorption of Au(III) ions on chelating polyacrylonitrile fibers containing imidazoline group, although the mechanism of reduction was not discussed [16]. In general, the higher activity of Au(III) and Pt(IV) in redox reaction with imidazolyl derivatives in comparison with Pd(II) can be related to their higher oxidation potential [37].…”

“…Covalent modification of polymers with imidazole-containing functional groups is of great interest due to the strong binding of d-metal ions to imidazole [13] and possibility to design materials with superior sorption characteristics applicable for metal ions recovery from leaching solutions, industrial wastes and natural waters [3,[14][15][16][17] In general, synthesis of imidazolecontaining sorbents is not well developed due to the low efficacy of known imidazole-containing reagents -imidazolecarboxaldehyde [18,19], 4(5)-chloromethylimidazole [20,21] N-substituted imidazole derivatives [14,15,17,22,23], and imidazole itself [24][25][26] -for polymer functionalization.…”

An overview of synthetic modification of nitrile group in polymers and applications

“…Preparation of chelating fiber containing ethylene diamine, carboxyl, and tetrazine groups (animo‐carboxyl‐tetrazine group) for separation of heavy metal ions were described from this group by the reaction of PAN with hydrazine followed by reaction with Ethylene diamine and caustic soda solution . Hydrazine modified chelating fiber containing an imidazoline or thioamide group was also developed by same group in 2002 . It was obtained through the functionalization of hydrazine modified fiber 31 with ethylene diamine 32 (Imidazole formation 33 ) and by the amination and sulfurization reaction of the modified PAN fiber (thioamide formation) under appropriate conditions (Scheme ).…”