Abstract
Numerous strategies have been devised to effectively extract uranium (U[VI] or 238U) from raw materials because it is a significant energy source. This study focused on the highly selective extraction of 238U isotopes from altered granite rock (AGR) utilizing bio-absorbents/extracts from Three-dimensional mesoporous silica monoliths (MSMs), which have been successfully created from affordable and sustainable resources like rice husk (RH). The MSMs exhibited micrometric particle sizes, mesoscopic hexagonal geometry, and irregular nano/ microspace voids and grooves along their surfaces. To establish specific binding sites for the extremely selective adsorption/trapping/capturing of ultratrace levels of 238U isotope at pH 3, the MSMs were modified with (2-diethylphosphatoethyl) triethoxy silane chelating agent. Considering that the spent adsorbent/extractor could be recycled/regenerated by using H2SO4 as a stripping agent, the recycled bio-adsorbents could be reused several times with high retention efficiency. The isotherm, kinetic models, and thermodynamic parameters of U(VI) extraction were investigated to describe the nature of adsorption between the bio-adsorbents/extractors and adsorbate species. Results indicated that the MSM and MMSM biosorbents were promising effective extractors for 238U isotopes due to (i) their natural sources; (ii) their contribution to the management of RH waste; (iii) their low cost and eco-friendliness; (iv) their high efficiency, sensitivity, selectivity, and capacity for the target ions; (v) their minimization of waste volume by enabling multiple reuse/cycles; (vi) and their retention of structural performance for several reuse/cycles that resulted in a cost-effective extraction/capture process. Our proposed natural, sustainable porous material and efficient approach might enable the efficient extraction of uranium species from different resources and the appropriate exploitation of natural/agro-waste for clean energy production.