SORPTION PROPERTIES OF HYDROLYZED STARCH GRAFT COPOLYMERS IN THE REMOVAL OF CADMIUM (II) AND COPPER (II) IONS FROM AQUEOUS MEDIA

Sorption properties of hydrolyzed starch graft poly (acrylic acid) and

starch graft poly(acrylonitrile) copolymers as sorbents for the removal of

Cd (II) and Cu(II) ions from aqueous solution in batch process were

assessed. The copolymers were prepared using methods as reported in

literature and were characterized in terms of morphology using scanning

electron microscopy, confirmation of sorbents produced using Fourier

transform infrared spectroscopy and thermal stability using

thermogravimetric analysis. The effect of contact time, initial concentration

and temperature were assessed to optimize the conditions for the sorption

of the metal ions. The experimental data were subjected to analysis using

the models; Langmuir, Freundlich, Temkin, Dubinin Radushkevich and

Sips isotherm models. The Freundlich and the Sips isotherms confirmed the

applicability of the models. The sorption capacity of the copolymers was

found to be 118.61mg/g for starch graft poly (acrylic acid) and 115.83mg/g

for starch graft poly (acrylonitrile). The sorption kinetics was assessed by

Lagergren pseudo first order, pseudo second order, Elovich equation,

Intraparticle diffusion and the liquid film diffusion models. The

experimental data fitted very well with the Elovich equation and the

Intraparticle kinetic models. The thermodynamic analysis showed that the

sorption was a spontaneous and endothermic process. The results indicated

that starch graft copolymers can be used as effective sorbents for Cd (II)

and Cu (II) removal from aqueous media.