Abstract
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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.