Because of their toxic potential, industrial effluents that contain cobalt ions have become
a severe environmental problem, unless properly treated. This research tends to study
the removal of cobalt from aqueous solution by Synechocystis pevalekii and Scenedesmus
bernardii, grown at different concentrations of Co2+ ions, and to study its impacts on
growth and metabolism. With increased concentrations of Co2+ ions, chlorophyll a, dry
weight, and total lipids decreased. The highest CAT and LOX activity was observed in
both tested algae at concentrations of 0.5 and 0.2 mgl−1 of Co2+. Langmuir, Freundlich,
Temkin and Dubinin–Radushkevich sorption isotherms were obtained by Sy. pevalekii
and Sc. bernardii, for the quantitative description of Co2+ uptake. All models studied
are well suited to describe the Co2+ isotherm biosorption equilibrium by Sy. pevalekii
than by Sc. bernardii. Dubinin–Radushkevich isotherm suggesting that the adsorption
mechanism was physical in nature. Sy pevalekii was an efficient to remove Co2+ ions than
Sc. bernardii. Nevertheless, affinity constant of Co2+ for Sc. bernardii was higher than that
of Sy. pevalekii, revealing that Sc. bernardii is more sensitive to Co2+ ion toxicity than Sy.
pevalekii. FTIR study of algae before and after biosorption showed the presence of groups
of amide, alkyl, hydroxyl, carbonyl and carboxyl responsible for Co2+ ions biosorption.
This indicates that Sy. pevalekii and Sc. bernardii can be used as a biosorbent for removing
heavy metals from various contaminated sites.