Competitive adsorption of metals on cabbage waste from multi-metal solutions

This study assessed the adsorption capacity of the agro-waste ‘cabbage’ as a biosorbent in single, binary,

ternary and quaternary sorption systems with Cu(II), Pb(II), Zn(II) and Cd(II) ions. Dried and ground powder

of cabbage waste (CW) was used for the sorption of metals ions. Carboxylic, hydroxyl, and amine

groups in cabbage waste were found to be the key functional groups for metal sorption. The adsorption

isotherms obtained could be well fitted to both the mono- and multi-metal models. In the competitive

adsorption systems, cabbage waste adsorbed larger amount of Pb(II) than the other three metals. However,

the presence of the competing ions suppressed the sorption of the target metal ions. Except the case

of binary system of Cd(II)–Zn(II) and Cd(II)–Cu(II), there was a linear inverse dependency between the

sorption capacities and number of different types of competitive metal ions.