Solid phase sensitive palladium(II) ions detection and recovery using ligand based efficient conjugate nanomaterials

• Ligand based conjugate nanomaterials was developed for palladium capturing.
• Very high sensitivity and selectivity were evaluated over other competing metal ions.
• The low detection limit and high adsorption were measured by the nanomaterials.

In this work, ligand based colorimetric conjugate nanomaterials was designed for highly selective and sensitive detection and removal of palladium (Pd(II)) ions. The proposed nanomaterials was exhibited the relatively rapid response and high selectivity toward Pd(II) ions without using additional reagents. Upon the addition of Pd(II) ions solution to the conjugate nanomaterials, the nanomaterials gave an absorption spectral intensity at around 425 nm and displayed a selective chromogenic behavior toward Pd(II) ions from colorless to light brown, which could be easily observed by the naked eye without using high-tech instruments. In addition, the solid-state nanomaterials showed great selectivity to Pd(II) ions at optimum conditions compared with diverse common ions as verified using UV–Vis–NIR analysis. Then the limit of detection by the nanomaterials was calculated to be 1.17 μg/L for Pd(II) ions. The pH of aqueous mediums was optimized through batch adsorption studies. The experimental data showed an interesting affinity between nanomaterials and Pd(II) ions at pH 2.0. The Pd(II) adsorption kinetic was fast, and the equilibrium data were represented well by the Langmuir adsorption isotherm equation with a monolayer adsorption capacity of 157.23 mg/g. Moreover, the conjugate nanomaterials was able to adsorbed the Pd(II) ions even in the presence of a high amount of foreign competing cations. More than 99% of Pd(II) ions was eluted in single contact using 0.10 M HCl–0.20 M thiourea and nanomaterials were reused several cycles of adsorption–elution–regeneration. Then the proposed solid design conjugate nanomaterials could be used as efficient and cost-effective material for selective Pd(II) ions detection and removal at optimum conditions.

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