A Novel Graphitic Biochar Derived from Banana Peels for Efficient PFAS Removal: Mechanistic Insight from Integrated...

Area of Science:

• Environmental Chemistry
• Materials Science
• Green Chemistry

Background:

• Per- and polyfluoroalkyl substances (PFASs) are persistent, bioaccumulative, and toxic environmental contaminants.
• Effective and affordable methods for PFAS removal from water are urgently needed.

Purpose of the Study:

• To synthesize and evaluate a porous graphitic biochar adsorbent (Zn-BBC) derived from banana peel waste for PFAS removal.
• To investigate the adsorption performance, kinetics, and mechanisms of Zn-BBC for various PFASs.

Main Methods:

• Zn-BBC was synthesized from banana peel waste using zinc chloride activation.
• Batch adsorption experiments were conducted to test PFAS removal efficiencies, kinetics, and isotherm models.
• The influence of pH, coexisting ions, and natural organic matter was assessed.
• Characterization techniques and DFT calculations were employed to elucidate adsorption mechanisms.

Main Results:

• Zn-BBC achieved >95% removal for ten legacy and alternative PFASs.
• Adsorption followed pseudo-second-order kinetics and was described by the Sips model, indicating chemisorption and surface heterogeneity.
• The adsorbent demonstrated robust performance across a wide pH range (3-9) and showed good reusability.
• While coexisting ions had minor effects, humic acid impacted the removal of certain PFASs; however, >85% removal was achieved in real water samples (except for PFBA).

Conclusions:

• Zn-BBC is a highly efficient, cost-effective, and sustainable adsorbent for removing diverse PFASs from water.
• The adsorption mechanism involves a combination of electrostatic, hydrophobic, π-CF, surface complexation, and hydrogen bonding interactions.
• This biochar adsorbent presents a promising solution for mitigating PFAS pollution in aquatic systems.