The heavy lanthanide of Thulium(III) separation and recovery using specific ligand-based facial composite adsorbent

The organic ligand of 3-(((5-ethoxybenzenethiol)imino)methyl)-salicylic acid (EBMS) was synthesized and then immobilized onto the mesoporous silica for the fabrication of facial composite adsorbent (FCA). The FCA was successfully utilized for the heavy lanthanide of Thulium(Tm(III)) separation, adsorption, and recovery in the solid-liquid approach. The FCA characterizations and affecting experimental parameters were assessed systematically. The Tm(III) ion was selected due to the high adsorption ability of the FCA according to the intra-series separation behaviors. The solution pH played a key role based on hydroxide formation in the basic pH region and a slightly acidic pH (3.50) was selected based on the high adsorption ability. The FCA was shown high kinetic performance and diverse competing metal ions did not interfere with Tm(III) adsorption. The Tm(III) adsorption was well-fitted with the Langmuir adsorption isotherm model with monolayer coverage and the maximum adsorption capacity was determined as 168.57 mg/g. The Tm(III) ion was strongly coordinated with the EBMS and the expected bond distance between Tm-N was shorter than the other bond length of Tm-S atoms in the complexation mechanism. The adsorbed Tm(III) ion was completely desorbed from the FCA with the suitable eluent of 0.25 M HNO3 and then simultaneously regenerated the FCA into the initial form without significant deterioration in the original functionality. The highest selectivity and maximum adsorption capacity of FCA to Tm(III) ions indicated that the proposed EBMS ligand-based composite adsorbent high potentiality to separate and recover the Tm(III) ions from waste samples effectively.