Simultaneous adsorption of toxic metals in binary systems using peanut and sheanut shells biochars

Area of Science:

• Environmental Science
• Materials Science
• Waste Management

Background:

• Agricultural waste, such as peanut and sheanut shells, presents a disposal challenge.
• Biochar production from waste materials is a promising avenue for resource recovery and environmental remediation.
• Heavy metal contamination in water bodies poses significant risks to ecosystems and human health.

Purpose of the Study:

• To investigate the potential of biochar derived from peanut and sheanut shells for the adsorption of lead (Pb²⁺), cadmium (Cd²⁺), and mercury (Hg²⁺) in binary systems.
• To evaluate the adsorption performance of biochar produced at different temperatures (350°C and 700°C).
• To determine the suitability of adsorption isotherm models (Langmuir and Freundlich) for describing the removal of these heavy metals.

Main Methods:

• Biochar was synthesized from peanut and sheanut shells at 350 ± 5 °C and 700 ± 5 °C.
• Adsorption experiments were conducted using binary systems of Pb²⁺, Cd²⁺, and Hg²⁺ at various concentrations (5:5 to 50:50 mg/L).
• Removal efficiencies were calculated, and adsorption data were fitted to Langmuir and Freundlich isotherm models.

Main Results:

• Biochar produced from peanut and sheanut shells demonstrated high removal efficiencies for Pb²⁺ (up to 100%), Cd²⁺ (88.70%-99.46%), and Hg²⁺ (98.20%-100%) in binary systems.
• The Langmuir model provided a better fit for the adsorption data compared to the Freundlich model, indicating monolayer adsorption.
• The presence of specific elements (Ca, K, Mg, Na, phosphates, and S) in the biochar influenced the adsorption mechanisms for different heavy metals.

Conclusions:

• Peanut and sheanut shell biochar exhibits excellent potential for the effective removal of lead, cadmium, and mercury from aqueous solutions.
• The biochar's chemical composition plays a crucial role in its heavy metal adsorption capabilities.
• Further investigation in real-world polluted water environments is recommended to validate the practical applicability of this biochar for wastewater treatment.