Pyrolyzed biomass-derived nanoparticles: a review of surface chemistry, contaminant mobility, and future research avenues to fill the gaps

Highlights

•	The surface functionality of pyrolyzed biomass-derived nanoparticles (PBNPs), described here as those derived from bulk biochar and activated carbon, differs from parent material.
•	The literature on PBNPs derived from biochar is growing, unlike that of activated carbon derived PBNPs.
•	There is a need for better understanding of co-transport of contaminants, photochemistry, and toxicity of PBNPs.

Abstract

Nanoparticles are abundant in the subsurface, soil, streams, and water bodies, and are often a critical control on elemental speciation, transport and cycling in the natural environment. This review provides an overview of pyrolyzed biomass-derived nanoparticles (PBNPs), their surface properties and reactivity towards aqueous species. We focus specifically on biochar-derived nanoparticles and activated carbon-derived nanoparticles which fall under our classification of PBNPs. Activated carbon-iron (nano)composites are included in some instances where there are significant gaps in literature because of their environmental relevance. Increased use of activated carbon, along with a resurgence in the manufacture and application of biochar for water treatment and soil amendment, has generated significant concerns about the mobility and toxicity of PBNPs derived from the bulk material in environmental applications. Recent examples are discussed to highlight current progress in understanding the influence of PBNPs on contaminant transport, followed by a critical discussion of gaps and future research directions.

Graphical Abstract

Funding

Natural Sciences and Engineering Research Council of Canada(RGPIN-2020-05289)