Asphalt, a fossil derived material, is used globally in construction for roads, pavements, and buildings and is known to generate volatile organic compounds (VOCs) upon exposure to heat and light. Several heterogeneous strategies have been reported for mitigating the issue of VOC emissions from asphalt by incorporating different inhibitors such as metal oxides, hydroxides, salts and porous substances as binders. However the direct use of inexpensive, accessible Earth-Abundant metals has not been extensively explored for their binding capability towards VOCs. In the present study, we have efficiently examined the coordination capability of metal salts towards asphalt-generated VOCs spectroscopically in HTE format using a plate reader. From these studies FeCl₃ emerged relative to other metal salts (metal = Mn, Co, Ni, Cu, Zn) as a promising candidate for the adsorption and retention of Lewis Basic compounds. Coordination of an example oxygen-containing VOC, benzofuran, to Fe^III yielded a paramagnetic semi-octahedral complex Fe(Bf)₃Cl₃ (Bf = benzofuran). Evaluation by thermal gravimetric analysis (TGA) coupled to infrared spectroscopy (IR) demonstrated that the complex was stable to 360 °C, visible light irradiation, and a variety of organic chemicals. The potential application of Fe was demonstrated by subjecting algae-derived biochar to FeCl₃ followed by the addition of benzofuran. It was discovered that this Fe-incorporated Biochar was successful at adsorbing benzofuran suggesting the possibility of introducing Fe salt to Biochar late-stage in processing to deter asphalt degradation and VOC emissions. An understanding of the binding and stability of Fe salts to VOCs provides insight into how sustainable infrastructure can be achieved.

Reem Nsouli

Appearances