Experimental Studies and Computational Calculations to Advance our Understanding of Biochar Surface Chemical Functionalities Responsible for Pollutants Removal

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Proposal: 1703052PI: Manuel Garcia-PerezThe high-temperature processing of plant-based (lignocellulosic) feedstocks is used to produce carbon-based materials (biochars) that are used to remove environmental pollutants such as pesticides and herbicides. Various parameters have been found to affect biochar quality, including feedstock composition, production conditions (e. g., temperature and reaction environment), and contaminants. The focus of this project is to increase our fundamental understanding of biochars, especially the nature of the active sites associated with different removal mechanisms and how these active sites are formed. In this project the PIs will integrate experimentation and modeling to gain an insight into biochar chemical structures (active sites) associated with several pollutant removal mechanisms. Results of this project may be used to guide optimization of the production of biochars for removing environmental contaminants. The capacity to remove organic (pesticides and herbicides, pharmaceutical and personal care products, plasticizers, dyes and polyaromatic compounds) inorganic (phosphates, nitrates, ammonium and heavy metals) and gaseous (H2S, CH4, and N2O) pollutants is an important attribute of biochars. The PIs plan to perform fundamental research to better understand biochar adsorption rates and mechanisms and the relationships of these factors to feedstock composition, carbonization, and post-carbonization conditions. They will study the mechanism of carbonaceous solids formation from cellulose, hemicellulose, and lignin and the role of different surface functionalities as active sites for the adsorption of pollutants. Density Functional Theory (DFT) calculations will be used to inform new deconvolution strategies for the analysis of Raman, XPS, and 13C-NMR spectra of biochars. The capacity of these materials to remove gaseous, organic, inorganic, and heavy metal pollutants will be evaluated, and the results will be correlated with biochar chemical composition results. The resulting correlations will permit the identification of relevant active sites in biochars. DFT calculations will be used to further explore the adsorption mechanisms associated with these active sites. This research will impact the field by providing details of mechanisms responsible for the formation of carbonaceous structures (polyaromatic deficiencies, oxygen and nitrogen containing functional groups) that are relevant for pollutant removal. Results of this study may guide the efficient production of inexpensive carbonaceous adsorbents as a powerful environmental tool.