Adsorptive removal of uranium from aqueous solutions using TiO2-diglycolamic acid functionalized graphitic carbon nitride (TiO2@gCN-HDGA) nanocomposite

In this work, a titanium dioxide integrated with diglycolamic acid functionalized graphitic carbon nitride (TiO₂@gCN-HDGA) nanocomposite was synthesized through a solvothermal route by coupling TiO₂ nanoparticles with diglycolamic acid modified graphitic carbon nitride (gCN) (HDGA). The structural and physicochemical features of the material was thoroughly examined through FT-IR, FE-SEM, XRD, TGA, BET, and XPS analyses. The ability of TiO₂@gCN-HDGA to capture uranium(VI) from aqueous and acidic environments was assessed using batch adsorption studies. The influence of contact time, adsorbent dosage, initial U(VI) concentration, and temperature on adsorption behavior were systematically evaluated. Kinetic modelling indicates that the adsorption process is best described by the pseudo-second-order model (R 2 = 0.99), and equilibrium profiles aligns well with the Langmuir isotherm model, yielding a maximum experimental adsorption capacity of 482.6 mg g −1 . The adsorption process is exothermic (ΔH = −2.35 kJ mol −1 ) and spontaneous (ΔG = −2.71 kJ mol −1 at 298 K), with a positive entropy change (ΔS = 0.017 kJ mol −1 K −1 ), confirming its thermodynamic feasibility. Desorption experiments demonstrated effective recovery of U(VI), with approximately 94% of the bound species released using dilute Na₂CO₃ solution. These findings demonstrate that TiO₂@gCN-HDGA offers remarkable adsorption capacity, favorable kinetic performance, and strong reusability, positioning it as a highly efficient material for remediation of U(VI)-contaminated waters.