In a comprehensive review published in Biochar, authors Zhenli Sun, Zhongshan Chen, Yuan Chen, Xishi Tai, Suhua Wang, Jiehong Lei, Qizhao Wang, Fuyou Fan, Bin Ma, and Xiangke Wang systematically evaluated biochar-based porous materials for the selective separation and recovery of radioactive uranium from complex aqueous environments. The rapid expansion of global nuclear energy infrastructure requires efficient recovery of uranium from nuclear wastewater, salt lakes, and natural seawater to maintain stable fuel supply chains while preventing toxic environmental contamination. Traditional extraction technologies face limitations including elevated chemical costs, poor selectivity against abundant background ions like calcium and sodium, and secondary waste generation. Thermally converted organic waste biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More provides a high-surface-area, stable framework that can be functionalized to serve as high-performance adsorbents, photocatalysts, or electrocatalysts for targeted radionuclide recovery.

Direct adsorption remains a primary pathway for large-scale preconcentration, where engineered functional groups drive high affinity for target uranium ions. Modifying biochar with phosphorus-containing ligands, amino groups, or organic molecules forms strong chemical coordination complexes with dissolved uranyl ions through targeted acid-base interactions. Modified materials achieved maximum static adsorption capacities reaching 1,616 milligrams per gram, alongside elevated distribution coefficients that allow selective binding even in natural seawater environments dominated by competing alkali and alkaline earth metals. In parallel, chemical precipitation mechanisms convert soluble uranium into solid mineral structures such as calcium uranyl phosphate hydrates. This localized surface precipitation prevents re-dissolution and secures permanent mineral immobilization across diverse solution conditions.

Photocatalytic and electrocatalytic strategies provide continuous pathways for extracting dissolved uranium without consuming chemical reagents. Incorporating semiconductor nanoparticles or single metal atoms into carbon matrices enhances visible light harvesting, accelerates electron-hole pair separation, and promotes rapid charge transfer to adsorbed uranyl species. Light-driven catalysis reduces soluble hexavalent uranium to insoluble tetravalent uranium dioxide solids or generates hydrogen peroxide to precipitate stable uranyl peroxide minerals. Electrocatalytic extraction utilizes functionalized carbon electrodes under applied electric potentials to induce continuous electrosorption, achieving uranium extraction capacities up to 987 milligrams per gram while converting dissolved species into solid bimetallic oxide deposits.

Machine learning models and data-driven computational tools further accelerate the optimization of biochar adsorbents. By analyzing structural descriptors, surface chemistry parameters, and solution variables, predictive algorithms identify key factors governing metal uptake and guide the targeted synthesis of tailored porous networks. Integrating smart design frameworks with multi-functional carbon materials establishes a bankable pathway for scaling radionuclide recovery from laboratory testing to real-world industrial and marine applications.

Source: Sun, Z., Chen, Z., Chen, Y., Tai, X., Wang, S., Lei, J., Wang, Q., Fan, F., Ma, B., & Wang, X. (2026). Highly selective separation of uranium by biochar-based porous materials through sorption, precipitation, photocatalysis, and electrocatalysis strategies. Biochar, 8(1), 119.