Transport of Biochar Particles in Saturated Granular Media: Effects of Pyrolysis Temperature and Particle Size

TLDR: Most biochars exhibited attractive acid-base interactions that impeded their transport, whereas the biochar with the greatest mobility had repulsive acid- base interaction, and greater retention of the MPs than that of the NPs was in contrast with the XDLVO predictions.

Abstract: Land application of biochar is increasingly being considered for potential agronomic and environmental benefits, e.g., enhancing carbon sequestration, nutrient retention, water holding capacity, and crop productivity; and reducing greenhouse gas emissions and bioavailability of environmental contaminants. However, little is known about the transport of biochar particles in the aqueous environment, which represents a critical knowledge gap because biochar particles can facilitate the transport of adsorbed contaminants. In this study, column experiments were conducted to investigate biochar particle transport and retention in water-saturated quartz sand. Specific factors considered included biochar feedstocks (wheat straw and pine needle), pyrolysis temperature (350 and 550 °C), and particle size (micrometer-particle (MP) and nanoparticle (NP)). Greater mobility was observed for the biochars of lower pyrolysis temperatures and smaller particle sizes. Extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) calcula...