Pre-modification strategy to prepare a novel Zr-based MOF for selective adsorption of Palladium(II) from solution

In this study, a novel metal organic framework (MOF) was prepared by pre-modification strategy and used as adsorbents to recover palladium ions in wastewater. The characterization indicates that the adsorbents have been successfully synthesized. The effects of various factors on the adsorption behavior of the adsorbents for Pd(II) was studied. Experimental research shows that the optimal pH of the adsorption process is 4.0. The adsorption kinetics and isotherms of Pd(II) on the adsorbents show that it conforms to pseudo-second-order and Langmuir models, respectively. Therefore, the adsorption reaction is a single layer adsorption on the uniform surface of the adsorbent, and chemical adsorption is the main rate-limiting step. According to thermodynamic analysis, the adsorption process is entropiezunahme, spontaneous and endothermic. The adsorption mechanism of Pd(II) on the adsorbents is mainly through the electrostatic action and chelation of Pd(II) with N and O atoms, and the reduction of Pd(II) to Pd(0) by N and O functional groups. The adsorbents can selectively uptake palladium ions from multi-ion wastewater, and after five adsorption–desorption cycles, the adsorption efficiency is still high. This new adsorbent has a wide application prospect in the field of palladium ion separation.