Temperature-tuned fish-scale biochar with two-dimensional homogeneous porous structure: A promising uranium extractant

The efficient treatment of uranium (U(VI)) is a challenging issue regarding radioactive wastewater management. As a byproduct of kitchen waste, fish scales with a unique collagen-hydroxyapatite structure have recently been studied in various fields. Only a few reports have focused on the preparation of temperature-tuned fish-scale biochar, especially with a two-dimensional homogeneous porous structure, for radioactive wastewater man-agement. Herein, a novel homogeneous porous activated biochar (AB) with fish scales as precursors was pre -pared by temperature control, and then ABs presented an adsorption capacity for U(VI) as high as 291.98 mg/g. Meanwhile, the effect of factors (pH, ionic strength, contact time, etc.) were comprehensively investigated. Thermodynamic parameters demonstrated that the adsorption of U(VI) was a spontaneous and endothermic process, and the chemisorption governed the adsorption process. Significantly, AB-750 with a greater specific surface area of 1074.73 m(2) g(-1) and higher surface roughness, was more suitable for the efficient capture of U (VI). The desorption and reusability studies also suggested that AB-750 was a promising candidate for long-term use. As illustrated with the spectral analysis, the carboxyl/amino groups on AB-750 were the main functional groups for the immobilization of U(VI). Thus, this work opened a new pathway for the preparation and appli-cation of fish-scale biochar for the efficient extraction of U(VI).

Automated summary

This study demonstrates the efficient extraction of uranium (U(VI)) using a novel activated biochar (AB) prepared from fish scales. The ABs showed a high adsorption capacity for U(VI), with thermodynamic analysis indicating a spontaneous and endothermic process dominated by chemisorption. AB-750, with a larger specific surface area and higher surface roughness, exhibited better capture efficiency for U(VI). Desorption and reusability studies confirmed the potential long-term use of AB-750. Spectral analysis revealed that carboxyl/amino groups on AB-750 were the main functional groups for immobilizing U(VI).