Numerous studies reported that HCl is very effective for desorbing
heavy metals from biosorbents (Singh et al., 2007; Tuzen and
Sari, 2010). We used 0.5 M HCl on Pb(II) and Cu(II) for Spirogyra
and Cladophora algae powders to test the adsorption–desorption
efficiency. We discovered that 0.5 M HCl was highly effective, with
up to an 85% recovery rate for both Spirogyra and Cladophora algae
powders. Furthermore, these two types of biomass continued to
maintain high stability even after five continuous adsorption–
desorption processes. The results are shown in Fig. 5.
In every cycle, Cladophora Pb(II) and Cu(II) recovery rates were
more than 88.0% and 82.6%, respectively, while those for Spirogyra
Pb(II) and Cu(II) were more than 92.5% and 85.1%, respectively. As discovered in studies of this type of adsorption–desorption cycle,
both Cladophora and Spirogyra were good biosorbents.