Copolymeric network crown ether resins with pendent functional group: Synthesis and adsorption for metal ions

Abstract

Three network crown ether resins with a high content of pendent functional groups were prepared and characterized by IR, elemental analysis, and thermal analysis. The slight variance of the thermal stability of the resins was related to the kind and content of the pendent functional group. The adsorption capacity of the resins for Mg(II), Cu(II), Co(II), Pb(II), and Hg(II) was determined. Toward Hg(II), the adsorption capacity of the resins was high and the adsorption process was easy and spontaneously performed. The XPS study showed that the adsorption of the NCR-SN resin toward Cu(II), Pb(II), and Hg(II) was mainly the coordinate interactions between the ligand atom (S, N) of the pendent functional groups and the metal ions.

Design of functionalization and structural analysis of organically-modified siliceous oxides with periodic structures for the development of sorbents for hazardous substances

“…Furthermore, the stoichiometric coordination of metal ions is expected, since the adsorbents have a molecular nature. In contrast, previous studies on synthetic polymers [14][15][16][17][18][19][20] have revealed that the ratio of N(adsorbate ion)/N(ionic pendant function) is far from stoichiometric and the capacity is, in most cases, below 1 mmol g À1 . Amine pendants have been often studied for the adsorption of oxyanions such as arsenate and chromate.…”

“…16 Crown ethers have also been chosen for the pendant groups for polymer adsorbents for hazardous aqueous cations. 19 The adsorption capacity of Hg 2+ has been reported as 0.5-1.5 mmol g À1 , depending on the pH conditions. 19 These results suggest that a considerable number of ''sleeping'' sites are generally present during metal ion sorption by polymer materials.…”

“…Many adsorptions are stoichiometric, unlike those that occur on polymer adsorbents. [14][15][16][17][18][19]116 The decrease in spacing between organic tethers causes repulsion between the adsorption sites and between neighbouring adsorbates. Thus, the optimization of density and the positioning of tethers are critical to synthesize organo-functionalized mesostructured silicas with maximum capacity and selectivity in the adsorption of target pollutants.…”