Fabrication of a highly porous, hydrophobic, and oleophilic bamboo sponge via a three-dimensional porous bamboo fiber network reconstruction

The development of high-performance and sustainable sorbents for oily wastewater remediation remains a critical challenge owing to the high cost, poor recyclability, and environmental incompatibility of conventional carbonaceous and polymer-based materials. Natural bamboo, a fast-growing and abundant lignocellulosic biomass, is a promising renewable feedstock. However, the dense native structure of natural bamboo significantly limits its application in adsorption technologies. This study presents a scalable and eco-friendly strategy for fabricating a highly porous hydrophobic/oleophilic bamboo sponge through the deconstruction and reconstruction of the bamboo fiber network, combined with silanization-induced surface functionalization. Chemical delignification and freeze-drying effectively disrupt the rigid bamboo cell wall and reconstruct a highly interconnected three-dimensional porous network with a porosity of 84.6%, representing a 4.6-fold increase compared with raw bamboo. The resulting hierarchical pore architecture, composed of aligned fiber channels and interlayer voids, provides rapid oil-transport pathways and large storage capacity. Subsequent silanization uniformly grafts low-surface-energy groups onto the pore surfaces, thereby imparting excellent hydrophobicity and superoleophilicity to the sponge. The synergistic integration of the interconnected porous network and tailored surface properties endows the sponge with an ultrahigh oil absorption capacity of 36.3 g/g, outperforming most conventional biomass- and polymer-based sorbents. Moreover, the elastic cellulose skeleton enables efficient oil recovery through simple mechanical squeezing, with minimal performance degradation over repeated cycles. This study presents a rational and structure-guided strategy for converting low-cost bamboo into a high-value functional material and establishes a fundamental structure–performance relationship for anisotropic biomass-derived sorbents. Owing to its renewability, scalability, and excellent oil adsorption performance, the bamboo sponge provides a promising and sustainable alternative to conventional sorbents for practical oily wastewater treatment and environmental remediation applications.