Synthesis, Characterization, Adsorption, and Isotopic Separation Studies of Pyrocatechol-Modified MCM-41 for Efficient Boron Removal

Abstract

Selected by the conductive value change (Δ) caused by generated proton in the boric acid-polyol solutions, pyrocatechol (CL) and nitropyrocatechol (NCL) were grafted into the mesoporous MCM-41 material for boron removal and isotopic separation. The adsorption kinetics, isotherms and thermodynamics, effect of pH, adsorption mechanism, regeneration, and isotopic separation performance on the new materials were explored in this study. The adsorption equilibrium was reached within 10 h, with the maximum boron adsorption capacity reaching up to 1.799 mmol g–1 for CL-MCM-41 at pH 9 and 1.548 mmol g–1 for NCL-MCM-41 at pH 12, respectively. In addition, the boron isotopic separation factor was measured to be 1.158, which was significantly higher than that of commercial IRA 743. After four cycles of elution with acetic acid of low concentration, approximately 80% of the original adsorption capacity could be maintained, which also outperformed the commercial resins.