Simultaneous heavy metal removal mechanism by dead macrophytes

Area of Science:

• Environmental Science
• Water Treatment
• Bioremediation

Background:

• Industrial activities release heavy metals into water bodies.
• Aquatic plant biomass is explored as a sustainable biosorbent for metal removal.
• Understanding biosorption mechanisms is crucial for effective water remediation.

Purpose of the Study:

• To investigate the simultaneous removal of heavy metals (Cd2+, Ni2+, Cu2+, Zn2+, Pb2+) using three dead aquatic macrophyte species.
• To analyze the sorption data using Langmuir and Freundlich isotherms and assess adsorption kinetics.
• To elucidate the ion exchange mechanism involved in heavy metal biosorption.

Main Methods:

• Biosorption experiments using dead biomass of Spirodela intermedia, Lemna minor, and Pistia stratiotes.
• Testing simultaneous removal of Cd2+, Ni2+, Cu2+, Zn2+, and Pb2+ from aqueous solutions.
• Analysis of sorption data using Langmuir and Freundlich isotherm models and first-order kinetics.

Main Results:

• Lemna minor exhibited the highest mean removal percentage for tested metals; Pistia stratiotes showed the lowest.
• Lead (Pb2+) and Cadmium (Cd2+) were removed most efficiently by all three macrophytes.
• Freundlich isotherm model best described the sorption data for all metals, indicating multilayer adsorption.

Conclusions:

• Dead aquatic macrophytes are effective biosorbents for simultaneous heavy metal removal from industrial wastewater.
• Biosorption efficiency varies among macrophyte species, with Lemna minor being particularly effective.
• The primary biosorption mechanism involves ion exchange, with Freundlich isotherm and first-order kinetics accurately modeling the process.