Investigation of ligand immobilized nano-composite adsorbent for efficient cerium(III) detection and recovery

• Organic–inorganic nano-composite adsorbent was fabricated for Ce(III) recovery.
• The adsorbent exhibited nano-sized cavities and high functionality in the acidic media.
• The Ce(III) was captured by naked-eye observation with high sensitivity.
• The adsorbent was also highly selective to Ce(III) with fast kinetic performances.

In this study, the organic ligand of 4-dodecyl-6-((4-(hexyloxy)phenyl)diazenyl) benzene-1,3-diol (DPDB) and mesoporous silica have been used to prepare the nano-composite adsorbent. The nano-composite adsorbent was fabricated by indirect immobilization of DPDB onto the mesoporous silica. The adsorbent was applied as an efficient material for the detection and recovery of Ce(III) ions in aqueous solutions. The adsorbent was exhibited fast and specific capturing of Ce(III) ions observable to the naked eye and based on the stable complex formation between DPDB and Ce(III) ions. Several experimental parameters such as solution pH, color optimization with initial concentrations, contact time, foreign ions effect and regeneration studies were systematically performed. The experimental data clarified that the Ce(III) was detected and adsorbed by the adsorbent at pH 2.50. The limit of detection for Ce(III) ions by the adsorbent was 0.12 μg/L and the sorption capacity was 150.37 mg/g at optimum conditions. The co-existing ions did not affect the Ce(III) detection and sorption and sorption uptake on the adsorbent reached equilibrium with rapid kinetic performances. The adsorbed Ce(III) was completely eluted with 0.30 M HNO3 and the adsorbent was regenerated into the initial form at the same time. In addition, the adsorbent was reused for several cycles without significant deterioration in its original functionality. Therefore, the proposed adsorbent allowed the sensitive, selective, easy to use, cost-effective, high efficiency, fast kinetics and stable capturing of Ce(III) ions even in the presence of diverse competing ions. In addition, there was no more secondary sludge produced in this operation and considered the adsorbent as the potential candidate in better replacement technology for capturing Ce(III) ions in a wide range of practical operations.

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