Adsorption performance of magnetic bamboo charcoal fibers activated by phosphoric acid for three radionuclides: uranium (VI), europium (III), and thorium (IV)
摘要
The treatment of radioactive wastewater from nuclear industry development remains an urgent challenge. Among various methods, adsorption stands out due to its efficiency and cost-effectiveness. In this study, bamboo fibers were used as raw materials to synthesis Magnetic Bamboo Charcoal Fibers Activated by Phosphoric acid (MBCAP) via pyrolysis and hydrothermal methods for the adsorption of U(VI), Eu(III), and Th(IV). Characterization revealed that MBCAP possesses a layered carbon fiber structure embedded with Fe3O4 microspheres, exhibiting a high specific surface area and abundant functional groups. Experimental results showed that adsorption was highly pH-dependent. While the adsorption of U(VI) and Eu(III) remained unaffected by ionic strength, Th(IV) adsorption was inhibited under high ionic strength conditions. At optimized conditions, MBCAP achieved adsorption efficiencies of 91.83% for U(VI), 93.2% for Eu(III), and 89.1% for Th(IV), with maximum Langmuir adsorption capacities of 77.02 mg/g, 23.80 mg/g, and 23.08 mg/g, respectively. Kinetic analyses indicated that the adsorption followed the pseudo-second-order model and Langmuir isotherm which means monolayer chemisorption is dominant, and there was likely some degree of surface heterogeneity. Thermodynamic analyses (ΔG0 < 0, ΔH0 > 0), suggesting a spontaneous, endothermic chemisorption process accompanied by multilayer adsorption. These findings demonstrate the promising potential of MBCAP for radioactive wastewater treatment.