Recycling of discarded face masks for modification and use in SBS-modified bitumen.

Since the outbreak of the COVID-19 pandemic, the discarded face masks have attracted widespread attention in society. In line with sustainable development, a physicochemical treatment method was used to recycle discarded face masks into styrene-butadiene-styrene (SBS) modified bitumen. Utilizing the highly adhesive polydopamine-polyethyleneimine (PDA-PEI) coating, it has improved the surface damage of the discarded face mask fibers (DFMF) caused by natural aging and mechanical fragmentation, simultaneously strengthening the connection between the fibers and bitumen. At 46 °C, the 2% embellish-face mask fiber (E-FMF)/SBS modified bitumen, compared to the 2%DFMF/SBS modified bitumen, exhibited improvements in complex modulus (G*), elastic modulus (G'), and loss modulus (G″) by 12.27%, 16.39%, and 13.35%, respectively. Furthermore, at 0.1 kPa and 3.2 kPa, the creep recovery rate (R) increased by 23.3% and 32%, and the average creep compliance (Jnr) decreased by 54.7% and 64%. It was demonstrated that DFMF adhered with the coating, were more effective in improving the mechanical properties, deformation resistance, and shear resistance of the bitumen. This approach enriches the application scenarios of discarded single-use face masks and supports environmental protection and road construction.

Study on the resourceful reuse in SBS-modified asphalt of waste bagasse fibers based on green modification with tannic acid and FeOOH.

Hydrophobic modification of bagasse fibers (BFs) through a green approach can promote its reuse in asphalt and enhance the utilization value of agricultural and forestry waste in road engineering. In contrast to traditional chemical modification, this study reports a new method for the hydrophobic modification of BFs using tannic acid (TA) and the in situ growth of FeOOH nanoparticles (NPs), resulting in FeOOH-TA-BF, which is used to prepare styrene-butadiene styrene (SBS)-modified asphalt. The experimental results show that the surface roughness, specific surface area, thermal stability, and hydrophobicity of the modified BF are improved, which is beneficial for enhancing the interface compatibility with asphalt. Specifically, compared with BF/SBS-modified asphalt, FeOOH-TA-BF/SBS-modified asphalt exhibits 39.21% and 23.26% increase in the elastic modulus G' and viscous modulus G″, respectively, at the optimal dosage of 2.5%, corresponding to 6.15-fold and 7.13-fold increase in the fatigue life at 2.5% and 5.0% strain respectively, and 22.0% improvement in shear resistance performance. In the meantime, 2.5-fold enhancement of the storage stability. Therefore, this study provides a simple, environmentally friendly, and efficient hydrophobic modification method that is of great significance for promoting the resource utilization of solid waste BF.