Adsorption of metals from mining-impacted water onto biochar from different sources
Citation:
Al-Abed, Souhail R., P. Pinto, M. Arambewela, Phillip M. Potter, M. Johnson, J. Novak, S. Kemp, AND J. McKernan. Adsorption of metals from mining-impacted water onto biochar from different sources. 258th American Chemical Society, San Diego, CA, August 25 - 29, 2019.
Impact/Purpose:
Toxic metal contamination transported via mining-impacted water contaminates superficial waters around the world. Metal adsorption is one of the most important technologies available for metal remediation. This research aims at using biochar, a material produced from waste that has been used as agricultural soil amendment and has been used for adsorption in a few studies. Our study involved metal adsorption on four different types of biochar and other three adsorbent materials aiming at finding successful metal removal at low cost. This research will have a wide range of interest from the decision-makers, researchers, and the communities affected by metal polluted waters from abandoned mine sites, contaminated watersheds, and other contaminated areas. This presentation will be part of a symposium dedicated to biochar manufacturing and applications in the ACS Fall 2019 conference.
Description:
The runoff from mine tailings in active and abandoned mine sites transport important amounts of dissolved and particulate metals into streams and water bodies, posing a serious risk for ecosystems and endangering drinking water sources. The remediation of these mining-impacted waters is challenging because a significant portion of the metals is transported in the dissolved form, which tends to be a recalcitrant problem. The removal of metals from these waters is usually carried out by precipitation, filtration, ion exchange, or adsorption. The adsorption of metals could be very effective but also cumbersome and expensive. An ideal adsorbent would come from a natural source that would not raise environmental concerns, would have high superficial area with capabilities to remove several contaminants at low cost. Biochar, a carbonaceous product of the thermal degradation of biomass, could be the ideal adsorbent for water treatment applications. We evaluated the removal of zinc and other metals using four biochars from different vendors with sorbent loading, initial metal concentration, surface area, and initial pH as variables. We found that three of the four tested biochars had a performance similar to other tested commercial adsorbents (>80% zinc removal efficiency), while the fourth biochar performed at lower removal rates (up to 40% zinc removal). The interaction between sorbed metals and the biochar surface was studied using spectroscopic analyses. Overall, we concluded that biochar can be an important alternative in mining-impacted water remediation at moderate costs.