There is an indication from one set of experiments using solutions with a mix of Cu and Zn
that there were differences in the ability of mussel shell to capture the different metal ions. In
this experiment the mussel shell showed a reduced ability to retain Zn while Cu continued to
be efficiently retained. In other studies Cu has typically been found to be adsorbed more
easily than other metals (Coşkun et al. 2006), although this can vary with the type of sorbent
media and pH (Wu and Zhou 2009). Unfortunately, in this current experiment no
measurements of pH were reported despite the potential for changes in pH to be caused by
chemical reactions between the dissolved metal compounds and the shell material (Färm
2002; Genç-Fuhrman et al. 2007; Wu and Zhou 2009). It is important for future research to
either measure pH or control for possible effects from varying pH