Hypercrosslinked microporous polymer networks for effective removal of toxic metal ions from water

Sulfonic acid-modified microporous hypercrosslinked polymers (SAM-HCPs) synthesized by sulfonation of microporous hypercrosslinked polymers (HCPs, also known as Davankov Resins) have been investigated as a high-capacity adsorbent for toxic metal ions. The materials were characterized using proton magnetic resonance (H-1 NMR), Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA), thermogravimetric analysis (TGA), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption method. The results show that the modified resins retained their original microporous structure and spherical morphology, and possess sulfonic acid groups as hydrophilic groups and active sites. Sulfonic acids-modified hypercrosslinked Davankov Resins (SAM-HCP-DR) have been found to attain very good adsorption capacity for metal ions (e.g., Cu2+ 51.45 mg g(-1) at 303 K, 54.82 mg g(-1) at 313 K, and 57.68 mg g(-1) at 323 K), which is due to the synergic effect of microporous structure and active sites. The kinetic data obtained from adsorption experiments supports a pseudo-second order model and adsorption isotherms obtained at different temperatures (303 K, 313 K and 323 K) are all fitted with the Langmuir isotherms. In addition, the thermodynamic parameters, i.e., Gibbs free energy change (Delta G(0)), enthalpy change (Delta H-0), entropy change (Delta S-0) of the adsorption process were calculated, and the results confirmed the adsorption to be spontaneous and endothermic. Moreover, these modified resins can be recycled several times with minimal loss of adsorption capacity and thus may have potential industrial applications. (C) 2010 Elsevier Inc. All rights reserved.