Maximizing Indoor Air Quality: The Role of Biochar Particle Size in Pollutant Adsorption

As public awareness of indoor air quality increases, the quest for effective and affordable purification methods is intensifying. A notable study delves into how the size of biochar particles, derived from bark, impacts their ability to adsorb airborne pollutants like formaldehyde and methanol.

Researchers prepared biochar from bark through grinding or ball milling, creating seven different size groups. These samples were then analyzed using various techniques to measure physical composition and structural properties. Interestingly, while most physical and X-ray diffraction (XRD) patterns remained consistent across different sizes, ball-milled samples had higher ash content and showed signs of contamination.

The study highlights that smaller biochar particles, especially those under 100 micrometers, demonstrated superior adsorption capabilities. This is largely due to their increased surface area and total pore volume, which were significantly enhanced by ball milling—by 102% and 48%, respectively.

However, it’s important to note the trade-offs with ball milling, such as potential contamination, higher energy consumption, and slower processing times. As such, simple mechanical grinding is recommended for reducing particle size to maintain the purity and efficiency of the biochar.

The research also found that the influence of particle size on adsorption efficiency was more pronounced at lower pollutant concentrations (1 ppm of formaldehyde). This suggests that in typical indoor environments, where pollutants are often at low concentrations, smaller biochar particles could be particularly effective.

This study underscores the potential of using sustainably sourced bark-derived biochar as a high-performance adsorbent for improving indoor air quality. By optimizing biochar particle size, it is possible to enhance air purification strategies without compromising on cost or environmental impact, marking a significant step forward in indoor health and sustainability.