The high organization displayed in biological materials can be partly conserved even after significant physico-chemical modifications. Various heat modifications of the polymeric system that constitutes the extracellular matrix can produce materials where complex nanoscale structures are formed while less thermally stable portions leave vacuums. Thus, through specific heat treatments of agricultural byproducts, such as nut shells, we produced highly porous carbonaceous materials (biochars) that could serve as water purifier or filtration system. 129Xe NMR was found to be a useful technique that is complementary to the conventional porosity measurements such as nitrogen adsorption isotherms. 129Xe NMR demonstrated the presence of nanoscale porosity that was influenced by the details of the heat treatment and post-treatment processes. In some cases, sustained or more extreme heat treatment caused increase in pore size, probably due to wall collapse. The charring process produced a residue that partially occluded the pores but could be removed by washing with water. These complex processes could be observed with 129Xe NMR at varying degrees of detail.Figure 1. Almond shell treated at 800 �C heat to produce biochar. Initial heat treatment (60 minutes) did not produce any measurable porosity (lower left 129Xe NMR spectrum), but further heat treatment (240 minutes, upper left spectrum) or washing with water (lower right spectrum) made pores appear. The porosity increased when both 240-minute heating and washing were applied (upper right spectrum).

Studies of biochars derived from agricultural materials using <sup>129</sup>Xe NMR and porosity measurements

247th National Meeting (2014)

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Studies of biochars derived from agricultural materials using 129Xe NMR and porosity measurements

Studies of biochars derived from agricultural materials using ¹²⁹Xe NMR and porosity measurements