Removal of Cr6+ from aqueous solution by some algae

Area of Science:

• Environmental Science
• Water Treatment
• Biotechnology

Background:

• Hexavalent chromium (Cr6+) is a toxic heavy metal pollutant.
• Effective and sustainable methods for Cr6+ removal from wastewater are crucial.

Purpose of the Study:

• To evaluate the biosorption capacity of five different dried algae species for Cr6+ removal.
• To determine optimal conditions (pH, concentration, time) for Cr6+ biosorption.
• To assess the applicability of Langmuir and Freundlich adsorption models.

Main Methods:

• Batch biosorption experiments were conducted using dried Halimeda tuna, Sargassum vulgare, Pterocladia capillacea, Hypnea musciformis, and Laurencia papillosa.
• Parameters such as pH, initial Cr6+ concentration, and agitation time were varied.
• Breakthrough curves were analyzed to determine adsorption quantities, equilibrium uptakes, and removal percentages.
• Adsorption isotherms were fitted using Langmuir and Freundlich models.

Main Results:

• Optimal pH for Cr6+ biosorption varied among algae species (1.0-3.0).
• Maximum chromium biosorption occurred at different contact times for each alga (60-180 min).
• Sargassum vulgare exhibited the highest maximum sorption capacity (33.0 mgg⁻¹), indicating its suitability for chromium removal.

Conclusions:

• Dried algae, particularly Sargassum vulgare, are effective biosorbents for hexavalent chromium.
• Biosorption efficiency is dependent on pH, initial metal concentration, and contact time.
• Further research into large-scale application of algal biosorbents for chromium remediation is warranted.