Valorization of pineapple leaf waste into Fe-Modified biochar for efficient H₂S adsorption

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Agricultural residues like pineapple leaves (PAL) are abundant but underutilized in Thailand.
• Hydrogen sulfide (H₂S) is a toxic and corrosive gas requiring efficient removal methods.
• Developing cost-effective and sustainable adsorbents is crucial for gas purification.

Purpose of the Study:

• To develop an efficient hydrogen sulfide (H₂S) adsorbent from pineapple leaf-derived biochar (PALC).
• To investigate the effect of FeCl₃ pretreatment and pyrolysis conditions on H₂S adsorption performance.
• To explore the potential of valorizing agricultural waste into functional materials for gas purification.

Main Methods:

• Pineapple leaves were pretreated with FeCl₃ and pyrolyzed at temperatures ranging from 400-800°C.
• PAL-to-Fe mass ratios were varied between 0.5-3.
• H₂S adsorption capacity was evaluated under varying humidity and CO₂ concentrations.
• Material characterization included X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations.

Main Results:

• The optimal adsorbent, 2Fe/PALC600, containing Fe₃O₄, exhibited a maximum H₂S adsorption capacity of 380.1 mg g⁻¹ at 40% relative humidity.
• Adsorption performance was significantly influenced by pore structure and iron species, which depend on pyrolysis temperature and iron loading.
• Humidity enhanced H₂S removal, whereas 40% CO₂ significantly suppressed adsorption due to competitive physisorption.

Conclusions:

• Fe-modified PAL-derived biochar is a promising, sustainable, and cost-effective material for H₂S removal.
• The study demonstrates effective valorization of agricultural waste into high-performance adsorbents.
• Understanding the role of pore structure, iron species, and environmental factors is key to optimizing adsorbent performance.