Efficient adsorptive and reductive removal of U(VI) and Se(IV) using porous hexagonal boron nitride supported nanoscale iron sulfide: Performance and mechanism

The removal of U(VI) and Se(IV) in an aqueous solution was investigated by batch experiments and characterized by spectroscopy techniques such as FTIR, XRD, SEM, TEM, XPS, using FeS@h-BN nanocomposite which was synthesized by hexagonal BN (h-BN) as the stabilizer anchored onto FeS nanoparticles to address the agglomeration of the FeS. The effects of pH, adsorbent concentration, contact time, and initial concentration of U(VI) and Se(IV) on FeS@h-BN adsorption U(VI) and Se(IV) were studied. Results showed that FeS@h-BN nanocomposite showed an excellent decontamination performance due to the large surface area and surface potential. A pseudo-second-order kinetic model well reflected the kinetic adsorption of U(VI) and Se(IV) which indicated chemical interaction mainly contributed to U(VI) and Se(IV) adsorption on FeS@h-BN. The adsorption process of removing U(VI) fitted Freundlich and D-R models well which presented multilayer adsorption on the nanocomposite surface. The Langmuir model fitted well with sorption isotherm data of Se(IV) removal displaying a single monolayer reaction between Se(IV) and FeS@h-BN. The adsorption of U(VI) and Se(IV) was high pH-dependent since pH affected the FeS@h-BN nanocomposite surface potential and U(VI) and Se(IV) speciation. The maximum sorption capacity of U(VI) and Se(IV) reached 163.11 and 196.39 mg/g, respectively. These results reveal that FeS@h-BN nanocomposite could be promising for the effective decontamination of U(VI) and Se(IV).