A series of macroporous amphoteric cryogels based on allylamine, methacrylic acid and acrylamide were synthesized by radical copolymerization of monomers in cryoconditions. The average molar composition of amphoteric cryogels was found from the potentiometric and conductimetric titration curves. The morphology of cryogels was evaluated by SEM. Cryogels are highly elastic and have continuous macroporous structure with 50-200 mm pores. The values of the isoelectric pH determined from the swelling experiments arranged between 3.5 and 4.3. Complexation of amphoteric with transition metal ions was studied. Cryogels with adsorbed copper, nickel, or cobalt ions have an intense colour due to formation of coordination and ionic bonds between metal ions and amine and/or carboxylic groups of cryogels. Metal ions entrapped within the pores of cryogels were reduced by treating aqueous solution of NaBH 4 . Formation of micron sized metals on the inner surface of cryogels was observed by SEM.

No abstract

Abstract. Macroporous amphoteric gels based on allylamine, methacrylic acid and acrylamide crosslinked by N,N!-methylenebisacrylamide were synthesized by radical copolymerization of monomers in cryoconditions. The composition of cryogels was determined by combination of potentiometric and conductimetric titrations. The morphology of cryogels was evaluated by scanning electron microscope (SEM). Cryogels exhibited sponge-like porous structure with pore size ranging from 50 to 200 µm. The values of the isoelectric points (IEPs) determined from the swelling experiments arranged between 3.5 and 4.3. The high adsorption-desorption capacity of amphoteric cryogels with respect to mM and trace concentrations of copper, nickel, and cobalt ions was demonstrated. It was shown that the macroporous amphoteric cryogels are able to adsorb up to 99.9% of copper, nickel, and cobalt ions from 10 -3 mol·L -1 aqueous solution.

No abstract

No abstract