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

Abstract

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 [PHis@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 10-800 mg/L for pH and metal ion concentration, respectively. The maximum adsorption capacity of heavy metal ions of P-His@PGMA cryogel discs were 6.9 mg/g for Pb(II), 6.4 mg/g for Cd(II), 5.6 mg/g for Cu(II) and 4.3 mg/g for > Zn(II). Desorption of heavy metal ions was studied with 0.1 M HNO 3 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. DH DS , DG ) were also calculated at different temperatures.

Poly-(l)-histidine immobilized cryogels for lysozyme purification

“…In conclusion, PGMA cryogel discs can be used as an alternative adsorbent for lysozyme purification.

Scheme 1.The chemical structure of poly- l -histidine (Çimen et al, 2015).

…”

A review of cryogels synthesis, characterization and applications on the removal of heavy metals from aqueous solutions

“…Also, cryogels have open-ended pores which contribute to the fast diffusion in contrast to the closed-end pores of conventional porous materials [57,58,105]. The relatively low surface area can be compensated with a high number of active sites distributed on the cryogel walls and also the adaptability of cryogels as the surface can be easily altered by adding functional groups and ligands, which can greatly contribute to the capacity and selectivity [26,47,52,57,60,71,106]. Moreover, hydrogels and cryogels have the ability to expand their structure due to their high swelling capacity [107,108].…”

“…Under these pH values, it is positively charged and repulsion between ligand and metal ions occurred. At higher pH the metal ions precipitation and competition with -OH ions may cause a decrease in adsorption capacity [106].…”

Covalent immobilization of papain onto poly(hydroxyethyl methacrylate)-chitosan cryogels for apple juice clarification

“…Cryogels are matrices produced by freeze-induced polymerization of the building precursors. These unusual hydrogels have become appealing due to their unique properties which can be listed as follows: large interconnected macropores; elasticity; good mechanical, physical, and chemical stability; easy preparation; low-cost; ecofriendly nature (Ç imen et al, 2015;Gun'ko et al, 2013). Cryogels are also utilized as stationary phases in various research areas including biotechnology, chromatography, biomedicine, environmental sciences, and biocatalysis (Plieva et al, 2007).…”