Development of melamine-impregnated alginate capsule for selective recovery of Pd(II) from a binary metal solution

An ionic barrier concept is proposed to introduce selectivity function to adsorbents towards precious metals (PMs) in the present study. As a model system, melamine-impregnated alginate capsule (MIAC) was prepared and used as a Pd(II) selective adsorbent from a binary metal solution containing Pt (IV) and Pd(II). The MIAC exhibited excellent Pd(II) selectivity for a pH around 4.3, where the selectivity coefficient reached a high value of 2190.66. In comparison to the very low Pt (IV) uptake, a high maximum uptake of Pd(II) was estimated of 316.92 +/- 9.50 mg/g by the Langmuir isotherm model. Sorptiondesorption studies showed that the MIAC had a good reutilization property. The selective process for Pd(II) recovery was proposed as follows: the electroneutral Pd(OH)(2) but not anionic PtCl5 first penetrate the outer ionic barrier; then, the penetrated Pd(OH)(2) was bound by the inner melamine through chelation. The ionic barrier-based sorbent thus can be considered as an alternative one for separation and recovery of Pd(II). (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

An ionic barrier concept was proposed to introduce selectivity function for precious metals (PMs) adsorption in this study. MIAC, as a model system, showed excellent Pd(II) selectivity and good reutilization property, which is beneficial for the separation and recovery of precious metals.