Biochar for volatile organic compound (VOC) removal: Sorption performance and governing mechanisms

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Sorption is an efficient, low-cost method for volatile organic compound (VOC) removal.
• Research on VOC sorption by biochar is limited, necessitating further investigation.

Purpose of the Study:

• To evaluate the VOC sorption potential and mechanisms of biochar.
• To assess the influence of feedstock and production temperature on biochar's sorption capacity.
• To determine the reusability of biochar for VOC removal.

Main Methods:

• Gas phase sorption experiments were conducted using 15 biochars from 5 feedstocks (pyrolyzed at 300, 450, 600°C).
• Three common VOCs (acetone, cyclohexane, toluene) were used as sorbates.
• Sorption capacities, mechanisms, and reusability over five cycles were analyzed.

Main Results:

• All tested biochars exhibited significant VOC sorption capacities (5.58-91.2 mg g⁻¹).
• Sorption capacity was influenced by biochar surface area and non-carbonized organic matter content.
• VOC removal decreased with increasing feedstock temperature; the process was exothermic.
• Both physical adsorption and partition mechanisms were key to VOC removal.
• Biochar demonstrated good reusability over five sorption-desorption cycles.

Conclusions:

• Biochar is a promising, cost-effective sorbent for gaseous VOC removal.
• Biochar's properties, influenced by feedstock and pyrolysis temperature, dictate its VOC sorption efficiency.
• The study confirms biochar's potential as a sustainable material for air pollution control.