Multifunctional carboxylated cellulose nanofibers/exfoliated bentonite/Ti3C2 aerogel for efficient oil adsorption and recovery: The dual effect of exfoliated bentonite and MXene

Abstract

Discharge of oily wastewater with poor fluidity could cause serious environmental pollution. Therefore, rapid and efficient removal and recovery of oil is still a global problem. Currently, two-dimensional (2D) Ti3C2 MXene materials with high photothermal performance have attracted extensive attention in photothermal-assisted crude oil wastewater treatment. However, the poor stability of Ti3C2 severely limits the application in the development of photothermal aerogels. In this study, porous CNF-C/BTex/Ti3C2 aerogel was constructed by synergistically introducing cost-effective exfoliated bentonite (BTex) and Ti3C2 MXene combined with carboxylated cellulose nanofibers (CNF-C) through a simple in situ co-precipitation coupling with microwave hydrothermal and solution impregnation processes. The introduced BTex efficiently restrained the oxidation of Ti3C2 during the preparation process, and synergistically enhanced the structural stability, mechanical and adsorption properties of aerogel. Specifically, CNF-C/BTex/Ti3C2 exhibited excellent stability (structural, thermal and chemical stability), thermal resistance, hydrophobic properties (water contact angle was 149°), and mechanical properties (full recovery at 60% strain), which was conducive to adsorption of common oils (up to 46–90 times than its original weight). In addition, CNF-C/BTex/Ti3C2 has outstanding photothermal conversion efficiency (light absorption efficiency was 99% and the surface temperature reached up to 75.2 °C under 1-sun irradiation:1 kW·m−2) and thermal conductivity (104 mW/m·K), which allows CNF-C/BTex/Ti3C2 to adsorb more than 48 times than its original weight of crude oil (adsorption capacity up to 48 g·g−1) under 1-sun irradiation (1 kW·m−2) within 25 s. Furthermore, enhanced adsorption mechanisms for common oils and high-viscosity crude oil have been proposed. The study provides a new option for the development of efficient and stable cellulose-based adsorbents for oily wastewater remediation by introducing low-cost bentonite and MXene.