Biochar‐mediated reductive transformation of nitro herbicides and explosives

Abstract

Abstract-Biochar, a subset of black carbon produced via pyrolysis of biomass, has received much attention in recent years due to its potential to address many important issues, from energy and climate to agriculture and environmental quality. Biochar is known to influence the fate and transport of organic contaminants, although its role has been generally assumed to be as an adsorbent. In this study, the authors investigated the ability of biochar to catalyze the reductive reactions of nitro herbicides and explosives. Two biochars, derived from poultry litter and wastewater biosolids, were found to promote the reductive removal of the dinitro herbicides pendimethalin and trifluralin and the explosives 2,4-dinitrotoluene and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by dithiothreitol. Parallel experiments using another black carbon material, graphite powder or granular activated carbon, in place of a biochar resulted in comparable rate enhancement to show reduction products, such as 2,4-diaminotoluene and formaldehyde. A cyclization product of trifluralin and reduction products of dinitrotoluene and RDX were detected only when biochar and dithiothreitol were both present, supporting the ability of biochar to promote redox reactions. Three possible catalysts, including graphene moieties, surface functional groups, and redox-active metals, in biochar may be responsible for the biochar-mediated reactions. The environmental significance, implications, and applications of this previously unrecognized role of biochar are discussed. Environ. Toxicol. Chem. 2013;32:501-508. # 2012 SETAC

Polymer/biomass-derived biochar for use as a sorbent and electron transfer mediator in environmental applications

“…5). This is consistent with the previously reported biochar-dithiothreitol-DNT system (Oh et al, 2013b). Copyrolyzed biochar with PS/PE and RS also showed similar results (data not shown).…”

Wood-Biochar-Supported Magnetite Nanoparticles for Remediation of PAH-Contaminated Estuary Sediment

“…In this process, a suitable magnetic oxide (namely, iron oxide) and its composite are used for PS oxidation to yield an effective reactive species because iron oxide is a more effective and stable catalyst as compared to soluble Fe 2+ ions for the catalytic oxidation of organic pollutants [9][10][11]. Biochar is a readily available porous carbonaceous material that is produced as a solid by-product by the thermal decomposition of organic materials under oxygen-limited conditions and subsequent modification by chemical and physical methods [12]. Biochar is used widely as a soil additive, for nutrient retention in agriculture, for the adsorption of metallic and organic contaminants in sediments, as an energy generation co-product, and for mitigating climate change, because of its wide availability, low cost, and environmental friendliness [13].…”

Measuring the bioavailability of polychlorinated biphenyls to earthworms in soil enriched with biochar or activated carbon using triolein-embedded cellulose acetate membrane

“…It has been reported that biochar contains persistent free radicals (PFRs), which exhibited the ability to activate oxygen for the generation of reactive oxygen species and degraded contaminants efficiently (Fang et al 2014(Fang et al , 2015. Moreover, these PFRs also exhibited the ability to mediate the electron transfer reactions, which would mediate the reductive degradation of contaminants (Oh et al 2013;Klüpfel et al 2014). Although the concentrations of detected high-chlorinated PCBs changed slightly in soils, other highchlorinated PCBs could also existe in this contaminated soil, and their concentrations were not quantified due to the lack of standards.…”