Surface Charge Effects on Adsorption of Solutes by Poplar and Elm Biochars

Authors: Peterson, Steven - Steve; Kim, Sanghoon; Adkins, Jason

Submitted to: C - Journal of Carbon Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/22/2021
Publication Date: 1/26/2021
Citation: Peterson, S.C., Kim, S., Adkins, J.E. 2021. Surface Charge Effects on Adsorption of Solutes by Poplar and Elm Biochars. C - Journal of Carbon Research. 7(1). Article 11. https://doi.org/10.3390/c7010011.
DOI: https://doi.org/10.3390/c7010011

Interpretive Summary: In this research, we examined how the surface electrical charge of biochars from elm and poplar tree species changed with processing temperature. These biochars had both positive and negative charges on their surface, which made them effective for adsorbing charged particles in aqueous solution. The biochars were more electrically conductive as the processing temperature was increased, and thus are able to adsorb charged contaminants in water more effectively. This research shows that biochars processed at high temperature from elm and poplar would be effective in water filtration to adsorb either positively or negatively charged contaminants. This research helps develop valuable biochar from renewable sources.

Technical Abstract: Elm and poplar are two tree species that can provide a large amount of low-value feedstock for biochar production due to their rapid growth rate (poplar), and susceptibility to disease and/or infestation (both elm and poplar). Biochar has been studied recently as filtration medium for water purification, as it provides a renewable alternative to activated carbon. In this work, the adsorption efficiency of biochars made from elm and poplar as a function of pyrolysis temperature were studied with positive, neutral, and negative dyes to determine what factors had the greatest effect on adsorption of these dyes. It was found that conductivity of the biochars increased with pyrolysis temperature, and that this factor was more important than surface area in terms of adsorbing charged dyes. Both elm and poplar biochars were not effective in adsorbing neutral dyes. This research demonstrates that elm and poplar biochars adsorb charged (either positively or negatively) solutes more efficiently than uncharged ones because they carry both charges themselves. Therefore, these biochars would make excellent candidates as renewable filtration media for charged solutes.