Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) are widely distributed in soils, sediments and clay deposits. They originate from natural processes as byproducts of chemical manufacturing and industrial waste incineration. So general these chemicals are hydrophobic, toxic, bioaccumulative and persistent in the environment. As such it is important to understand their environmental fate, and their risks to human and ecosystem health. Recently, in-situ sorbent amendments using activated carbon and similar carbonaceous geosorbents (e.g. biochars) has been suggested as a new approach for management of contaminated soils and sediments. This approach relies on the ability of added sorbents to sequester PCDD/Fs and reduce their availabilities to target organisms. We have examined sorption/desorption processes of diobenzo-p-dioxin/dibenzofuran by activated carbons and biochars. Both dibenzo-p-dioxin and dibenzofuran were significantly sorbed by these carbonaceous sorbents (CGs) with sorption coefficients ranging from 480 to 4000 L/kg. Sorption by the CGs was much greater than soil organic matter as exemplify by the comparison with sorption by Pahokee Peat Soil. It is interesting to note that dibenzo-p-dioxin manifested reversible sorption/desorption process in activated carbons, whereas dibenzofuran desorption was observed to be irreversible to sorption. The presence of humic acid did not attenuate dibenzo-p-dioxin and dibenzofuran sorption by the CGs. In fact, humic acid coatings on the CG surfaces (~2% by weight) enhanced sorption of dibenzo-p-dioxin/dibenzofuran up to four folds compared to sorption by the pristine CGs. Understanding dibenzo-p-dioxin/dibenzofuran sorption by CGs is essential to evaluating their bioavailability and exposure to human health, and the potential to developing remediation strategy.

Sorption of dibenzo-p-dioxin/dibenzofuran by high surface area carbonaceous geosorbents

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.