Key points are not available for this paper at this time.
This paper investigates the role of phenolic compounds in biochar's adsorption capacity toward volatile organic compounds (VOCs) emitted from asphalt. Considering the impact of the preparation technique on biochar's composition, our findings show that the biochar produced through the fixed-bed technique contained more functional groups than the biochar produced through the fluidized-bed technique. Specifically, Fourier transform infrared analysis showed a higher concentration of phenolic OH groups in fixed-bed biochar, consistent with its nearly 3-fold higher oxygen content (6.37 ± 0.52 wt %) compared to fluidized-bed biochar (2.36 ± 0.54 wt %). Additionally, fixed-bed biochar contains significant concentrations of inorganic elements, such as Ca (8.103 g/kg), Al (6.904 g/kg), K (6.365 g/kg), and Fe (4.397 g/kg). Our density functional theory (DFT)-based molecular modeling revealed that phenolic groups directly influence the interaction of metal sites on biochar with the VOCs, benzoic acid, benzofuran, and dibenzothiophene. Consequently, the biochar model surface containing phenolic OH groups outperforms VOC adsorption compared with the pristine biochar surface lacking any phenolic OH groups. DFT results were validated by using UV–vis absorption studies, which demonstrated that phenolic OH-rich biochar was able to adsorb higher concentrations of benzofuran, benzoic acid, and dibenzothiophene. In addition, thermogravimetric analysis confirmed the biochar's ability to adsorb VOCs and retain them even under high temperatures. The study outcomes provide insight into the role of phenolic functional groups in the performance of the biochar in VOC adsorption. This in turn promotes the use of biochar in asphalt as a means of sequestering anthropogenic CO2 and reducing the emission of VOCs.
Mousavi et al. (Wed,) studied this question.