Multifunctional MnO2 nanorods-modified wood sponge for water remediation: Applications for heavy metal sorption and oil/water separation

Abstract

This study focuses on the development of a wood sponge (WS) modified with MnO₂ nanorods (MnO₂/WS) from balsa natural wood, as an abundant environmental-friendly raw material, to adsorb organic solvents, oils, and heavy metal ions from water. The MnO₂/WS composite exhibits an exceptionally low density of 0.014 g cm^− 3 and a high porosity exceeding 97%. MnO₂/WS demonstrates successful sorption-desorption cycles over 20 iterations. Zeta potential analysis reveals the negative charge (-22.31 mV) of MnO₂ nanorods at pH 4.68, underscoring their affinity for adsorbing positively-charged heavy metal ions commonly found in industrial effluents. Moreover, WS exhibits exceptional mechanical robustness, enduring 1000 stress-strain cycles with high shape recovery, ensuring its durability under operational conditions. Data above proved several strengths for MnO₂/WS, such as cost-effective production process, high reusability, remarkable sorption capacities for carbon tetrachloride and soybean oil at 29.56 and 17.65 times its mass, respectively, efficient performance, and the capability to produce potable water from real industrial effluents position MnO₂/WS as an ideal solution for mitigating water crises.