Biomass-derived hydrogel enables high-efficiency boron extraction from nuclear wastewater via green selective adsorption and rapid regeneration

Boron contamination in nuclear power plant cooling systems poses critical threats to aquatic ecosystems and human health due to its bioaccumulation and chronic toxicity. Targeting recalcitrant boron in nuclear effluents, we engineer a green and regenerable hydrogel adsorbent based on cellulose nanocrystal (CNC), polyethyleneimine (PEI), and polyvinyl alcohol (PVA) for highly selective boron removal from nuclear wastewater. By incorporating PAA-grafted CNC with PEI and PVA, a three-dimensional porous network was constructed, offering abundant adsorption sites. The optimized hydrogel (with PEI-PVA mass ratio of 1:2) exhibited a maximum boron adsorption capacity of 46.48 mg·g −1 , which is 40–60 % higher than other boron adsorbents, and reached equilibrium within 180 min. The adsorption process was highly pH-dependent, with optimal performance at pH 9, where boron speciates as B(OH) 4 − and strongly interacts with protonated amine and hydroxyl groups via electrostatic attraction and complexation. Kinetic and isotherm analyses indicated that the adsorption follows a pseudo-second-order model and Langmuir monolayer adsorption, confirming a chemisorption-dominated mechanism. The hydrogel also demonstrated strong anti-interference capability against common coexisting ions and excellent reusability over multiple adsorption-desorption cycles. With its high efficiency, outstanding selectivity, and sustainable design, this biomass-based hydrogel shows great potential for practical boron removal in nuclear wastewater treatment.