Microwave-assisted synthesis of hierarchical mesoporous nano-TiO2/cellulose composites for rapid adsorption of Pb2+

•Microwave irradiation was applied to produce nano-TiO2/cellulose composite fibers.•100 nm raspberry-like TiO2 composed of 10 nm primary particles were formed.•Composites fabricated by in situ TiO2 growth outperformed due to large surface area.•Composites with hierarchical surface structure lead to rapid adsorption of Pb2+.•The adsorption was due to electrostatic interaction and the fibers were reusable.

Cellulose fibers were used as substrates to induce the formation of nano-TiO2 via heterogeneous titanium oxysulfate hydrolysis under microwave irradiation. The microwave provided fast heating for the one-pot reaction at 90 °C and contributed to the generation of 10 nm anatase TiO2 nanoparticles. These spherical particles further fused into 100 nm raspberry-like mesoporous TiO2 agglomerates uniformly distributed on the cellulose surface. The composite material was able to adsorb Pb2+ very rapidly from simulated wastewater with a maximum capacity of 42.5 mg/g. The adsorption, characterized by pseudo-second order kinetics and Freundlich isotherm, was attributed to the reaction between the hydroxyl groups of TiO2 and Pb2+ to form PbO bond, as indicated by XPS analysis. The adsorbent can be easily regenerated for a number of times without significant reduction in adsorption performances.