Poly-L-Histidine Attached Poly(glycidyl methacrylate) Cryogels for Heavy Metal Removal


JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY, vol.52, no.9, pp.724-731, 2015 (SCI-Expanded) identifier identifier


Poly-L-histidine immobilized poly(glycidyl methacrylate) (PGMA) cryogel discs were used for the removal of heavy metal ions [Pb(II), Cd(II), Zn(II) and Cu(II)] from aqueous solutions. In the first step, PGMA cryogel discs were synthesized using glycidyl methacrylate (GMA) as a basic monomer and methylene bisacrylamide (MBAAm) as a cross linker in order to introduce active epoxy groups through the polymeric backbone. Then, the metal chelating groups are incorporated to cryogel discs by immobilizing poly-L-histidine (mol wt 5000) having poly-imidazole ring. The swelling test, fourier transform infrared spectroscopy and scanning electron microscopy were performed to characterize both the PGMA and poly-L-histidine immobilized PGMA [P-His@PGMA] cryogel discs. The effects of the metal ion concentration and pH on the adsorption capacity were studied. These parameters were varied between 3.0-6.0 and 10-800mg/L for pH and metal ion concentration, respectively. The maximum adsorption capacity of heavy metal ions of P-His@PGMA cryogel discs were 6.9mg/g for Pb(II), 6.4mg/g for Cd(II), 5.6mg/g for Cu(II) and 4.3mg/g for > Zn(II). Desorption of heavy metal ions was studied with 0.1M HNO3 solution. It was observed that cryogel discs could be recurrently used without important loss in the adsorption amount after five repetitive adsorption/desorption processes. Adsorption isotherms were fitted to Langmuir model and adsorption kinetics were suited to pseudo-second order model. Thermodynamic parameters (i.e. H degrees S degrees, G degrees) were also calculated at different temperatures.