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

This study presents the development of a wood sponge (WS) modified with MnO₂ nanorods (MnO₂/WS) derived from balsa natural wood, an abundant and environmentally friendly raw material, for the adsorption of 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 of approximately 97%. It demonstrates consistent sorption-desorption performance over 20 cycles. Zeta potential analysis reveals that MnO₂ nanorods carry a negative charge (-22.31 mV) at pH 4.68, indicating their affinity for adsorbing positively charged heavy metal ions, which are commonly found in industrial effluents. Moreover, WS shows remarkable mechanical robustness, enduring 1000 stress-strain cycles with high shape recovery, ensuring its durability under operational conditions. The data highlight several strengths of MnO₂/WS, including cost-effective production process, high reusability, remarkable sorption capacities for carbon tetrachloride and soybean oil (29.56 and 17.65 times its mass, respectively), and efficient performance. Its capability to produce potable water from real industrial effluents positions MnO₂/WS as an ideal solution for addressing water crises.