Modified coconut shell biochars (MCSBCs): Fabrication and their adsorptions for Pb(II)

Area of Science:

• Environmental Chemistry
• Materials Science
• Adsorption Science

Background:

• Heavy metal contamination, particularly lead (Pb(II)), poses significant environmental and health risks.
• Developing cost-effective and efficient adsorbents for heavy metal removal is crucial for water remediation.

Purpose of the Study:

• To fabricate modified coconut shell biochars (MCSBCs) using ZnCl2 and KMnO4 as inorganic modifiers.
• To evaluate the adsorption performance of MCSBCs for Pb(II) removal from aqueous solutions.
• To investigate the influence of chemical modification on biochar properties and adsorption mechanisms.

Main Methods:

• Coconut shells were pyrolyzed to produce biochar, then modified with ZnCl2 and KMnO4.
• Characterization of biochar properties using FT-IR, TGA, SEM, and BET techniques.
• Batch adsorption experiments were conducted to study Pb(II) removal under varying conditions (pH, contact time, concentration, temperature).

Main Results:

• Modified coconut shell biochars (MCSBCs) exhibited enhanced Pb(II) adsorption capacities, reaching 93.666 mg/g for Mn-modified biochar.
• Adsorption kinetics followed Lagergren first-order and Avrami fractional-order models, while isotherms best fit Langmuir and Sips models.
• While surface area decreased upon modification, pore diameter changes were minimal, suggesting chemical functional groups play a key role in adsorption.

Conclusions:

• Chemical modification of coconut shell biochar with ZnCl2 and KMnO4 significantly improves Pb(II) adsorption.
• MCSBCs demonstrate high efficiency and potential for practical application in treating lead-contaminated wastewater.
• The study highlights the effectiveness of biochar modification for developing advanced water purification materials.