As a replacement for activated carbon, biochar was synthesized and used for the adsorptive removal of formaldehyde and nitrogen oxide. Biochar was produced from the fast pyrolysis of the red marine macro alga, Pyropia tenera. The P. tenera char was then activated with steam, ammonia and KOH to alter its characteristics. The adsorption of formaldehyde, which is one of the main indoor air pollutants, onto the seaweed char was performed using 1-ppm formaldehyde and the char was activated using a range of methods. The char activated with both the KOH and ammonia treatments showed the highest adsorptive removal efficiency, followed by KOH-treated char, ammonia-treated char, steam-treated char, and non-activated char. The removal of 1000-ppm NO over untreated char, KOH-treated char, and activated carbon was also tested. While the untreated char exhibited little activity, the KOH-treated char removed 80% of the NO at 50°C, which was an even higher NO removal efficiency than that achieved by activated carbon.

• Heejin Lee(School of Environmental Engineering, University of Seoul, Seoul 02504, Korea) The authors have contributed equally in
• Rae-su Park(Department of Bioenvironmental & Chemical Engineering, Chosun College of Science & Technology, Gwangju 61453, Korea)
• Hyung Won Lee(School of Environmental Engineering, University of Seoul, Seoul 02504, Korea) The authors have contributed equally in
• Yeojin Hong(School of Environmental Engineering, University of Seoul, Seoul 02504, Korea)
• Yejin Lee(School of Environmental Engineering, University of Seoul, Seoul 02504, Korea)
• Sung Hoon Park(Department of Environmental Engineering, Sunchon National University, Suncheon 57922, Korea)
• Sang-Chul Jung(Department of Environmental Engineering, Sunchon National University, Suncheon 57922, Korea)
• Kyung-Seun Yoo(Department of Environmental Engineering, Kwangwoon University, Seoul 01897, Korea)
• Jong-Ki Jeon(Department of Chemical Engineering, Kongju National University, Cheonan 31080, Korea)
• Young-Kwon Park(School of Environmental Engineering, University of Seoul, Seoul 02504, Korea) Corresponding Author