Encapsulating carbon-coated nano zero-valent iron particles with biomass-derived carbon aerogel for efficient uranium extraction from uranium-containing wastewater

Encapsulating nano zero-valent iron particles with biomass-derived carbon is a promising strategy to achieve efficient uranium extraction by avoiding agglomeration and oxidation of nano zero-valent iron. Herein, we develop distinctive carbon-encapsulated nano zero-valent iron particles with konjac glucomannan-derived carbon aerogel for reduction-assisted uranium extraction. The nano zero-valent iron particles encapsulated in konjac glucomannan-derived carbon are composed of γ-Fe and a small part of α-Fe, in which γ-Fe with a stable carbon shell reduces the passivation rate, and the konjac glucomannan-derived carbon support prevents the nano zero-valent iron particles from agglomerating. U(VI) enrichment ratio via carbon-encapsulated nano zero-valent iron particles with konjac glucomannan-derived carbon aerogel reached up to 90.1% within 60 min in 200 mg/L uranium-containing wastewater, with U(VI) enrichment capacity of 720.8 mg/g. The mechanistic research revealed the oxygen-containing functional groups on konjac glucomannan-derived carbon confine UO22+, electrons on the nano zero-valent iron particles further transferred to konjac glucomannan-derived carbon, thereby realizing the reduction and fixation of uranium. Carbon-encapsulated nano zero-valent iron particles with konjac glucomannan-derived carbon aerogel can be a promising adsorption-reduction coupling material for multi-environment systems, providing a successful example for the purification of uranium-containing wastewater. [Display omitted] •Bio-assembly technology improved nZVI particles dispersibility.•KGMC encapsulated carbon-coated nZVI particles to enhance the stability of nZVI.•Fast adsorption kinetics: 75.7% removal efficiency was achieved in 10 min.•The presence of coexisting ions and organics scarcely affected the enrichment of uranium by nZVI@KGMC.