Taiwo Akinleye | Washington State University

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Presentation Description

Despite the success recorded in the last few years in isolating and identifying the emerging toxic contaminant-tire-wear-derived N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD-q), the prevention of 6PPD-q transport from its source, i.e., mostly road pavement surface, to the roadside soil remains elusive. Therefore, this study explores the use of engineered biochar in mitigating and reducing the transport of 6PPD-q in roadside soils. In light of recent advances in modifying the surface functional groups on biochar and its application in soil remediation, our study seeks to leverage chemical oxidation techniques to functionalize the biochar surface for the adsorption and retention of 6PPD-q. We hypothesize that phenolic (-OH), carbonyl (C=O), and quinone groups are suitable candidates for the adsorption of 6PPD-q due to their ability to undergo redox reactions and form pi-pi (π-π) interactions with aromatic compounds. To test our hypothesis, we have designed laboratory experiments to engineer the formation of these functional surface groups using chemical oxidation methods. Using chemical analysis methods, including Fourier transform infrared spectroscopy (FTIR) and Boehm titration, we evaluate the formation and abundance of the targeted functional groups. The microstructure of the engineered biochar is investigated using a scanning electron microscope, and the elemental composition is determined using energy-dispersive X-ray spectroscopy. Batch experiments are conducted to investigate the adsorption kinetics of 6PPD-q onto the modified biochar and evaluated using several adsorption isotherms. Soil column experiments are carried out incorporating the modified biochar in the soil to assess the effectiveness of the modified biochar in mitigating 6PPD-q contamination in soil environments. The changes in the microstructure of the biochar before and after modification are also examined. 6PPD-q adsorption on the engineered biochar surface is evaluated accordingly from the batch and soil column experiments. The results are analyzed to evaluate and quantify the formation of the surface functional group of interest and the corresponding benefits of mitigating contamination.

Keywords: N-(1,3-dimethyl butyl)-N′-phenyl-p-phenylenediamine (6PPD-q), surface functional groups, adsorption.

Speaker Biography

Taiwo O. Akinleye, S.M.ASCE is a Graduate Research Assistant, Department of Civil and Environmental Engineering at Washington State University in Pullman, WA.

Co-presenters

Xianming Shi

Presentation File