Aramid nanofibers/biochar nanosheets co-assembled composites for wastewater remediation under harsh environments

Nanoscale biochar is a promising material for the remediation of polluted water due to its low-cost sustainability, nevertheless, which still hindered by the self-aggregation and vulnerability issues in actual wastewater. In this work, biochar nanosheets (BCN) were successfully molded into membranes and aerogels with the help of aramid nanofibers (ANF) through a co-assembled process. Ascribing to the improved molecular sieving effects and electrostatic interactions of co-assembled membranes, as well as the superior chemical and thermal stabilities, the resultant ANF/BCN x membranes exhibited favorable dye separation performances toward rhodamine 6 G (R6G) even under high-temperature (e.g., ∼96.1 L·m −2 ·h −1 ·bar −1 and ∼97.4% at 80 °C) and strong acidic conditions (e.g., ∼84.1 L·m −2 ·h −1 ·bar −1 and ∼97.9% for 10 wt% H 2 SO 4 solutions). Besides, due to the reduced vaporization enthalpy, the ANF/BCN x aerogels as solar steam generators also demonstrated promising capability for clean water production even in 5 wt% H 2 SO 4 solutions (an evaporation rate of ∼1.0 kg·m −2 ·h −1 and an impressive efficiency of ∼89.9% under one sun illumination). Compared to conventional biochar materials, this work offered simple feasible morphology engineering designs to prepare multifunctional biochar-based composites with unique co-assemble structures, while also demonstrated great potential in wastewater remediation under extreme conditions.