Sorption and desorption of Cu and Cd by macroalgae and microalgae

Area of Science:

• Environmental Science
• Marine Biology
• Biotechnology

Background:

• Heavy metal pollution from industrial activities poses significant risks to aquatic ecosystems and human health.
• Algae, particularly macroalgae and microalgae, are increasingly recognized for their potential in bioremediation due to their biosorptive properties.

Purpose of the Study:

• To investigate the sorption and desorption capacities of different algal species for copper (Cu) and cadmium (Cd).
• To determine the optimal pH conditions and the influence of competing cations on metal sorption by algae.
• To evaluate the reusability of algal biomass for heavy metal removal in water treatment.

Main Methods:

• Studied sorption and desorption of Cu and Cd using two brown macroalgae (Laminaria japonica, Sargassum kjellmanianum) and five microalgae.
• Determined optimal pH for sorption and analyzed the effect of other cations.
• Applied Freundlich equation to model sorption isotherms.
• Investigated desorption efficiency using HCl and EDTA solutions.

Main Results:

• Brown macroalgae exhibited high sorption capacities at pH 4.0-5.0; microalgae showed optimal sorption at pH 6.7.
• Presence of other cations reduced sorption, indicating competition for binding sites.
• Sorption isotherms followed the Freundlich equation, suggesting diverse sorption mechanisms.
• Spirulina platensis showed the highest Cd sorption capacity among microalgae.
• HCl and EDTA effectively desorbed up to 99.5% of sorbed metals from macroalgae.
• Regenerated biomass retained its sorption performance.

Conclusions:

• Algal species demonstrate significant potential for Cu and Cd removal from aqueous solutions.
• Optimal pH conditions and cation competition are critical factors in algal metal sorption.
• Algal biomass can be effectively regenerated and reused, highlighting its sustainability for water and wastewater treatment applications.