Aminated lignin derived from diethylenetriamine and formaldehyde: A high-performance adsorbent for uranium(VI) removal from aqueous solutions

A novel DETA/Formaldehyde-modified lignin adsorbent was developed, showing enhanced affinity for U(VI). • The adsorbent achieved a maximum U(VI) adsorption capacity of 315.58 mg·g −1  under optimized preparation conditions. • Aminated lignin has better uranium adsorption performance than pristine lignin, showing great potential for uranium recovery. This study investigated the uranium adsorption performance of a polyamine/aldehyde-modified alkali lignin system. Five polyamines with different structural characteristics, including 1,3-propanediamine, 1,4-butanediamine, diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA), were employed as amination agents for lignin modification to evaluate the effects of polyamine incorporation on uranium adsorption capacity, adsorption rate, and selectivity. Experimental results showed that DETA/formaldehyde-modified lignin achieved a maximum U(VI) adsorption capacity of 315.58 mg·g −1 at pH 4.0 and 298.15 K, with an initial U(VI) concentration of 30 mg·L −1 and an adsorbent dosage of 33 mg·L −1 . Adsorption kinetic and thermodynamic analyses indicated that the adsorption process was a spontaneous, endothermic, and mon o layer chemisorption process. SEM, FTIR, and XPS characterizations demonstrated that the introduced amino groups significantly enhanced the affinity of the adsorbent toward U(VI). Compared with unmodified alkaline lignin, DETA/Formaldehyde-modified lignin exhibited a significantly enhanced uranium adsorption capacity.