Preparation of a novel porous organic polymer for selective extraction/determination of palladium ions from water samples

Abstract

In this research, a new porphyrin-based porous organic polymer (POP), named here PPOP-UOZ-1 (UOZ stands for the University of Zabol), was synthesized through a solvothermal condensation reaction between 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP, Porph-NH₂) and 2,2'-[ethane-1,2-diylbis(oxy)]dibenzaldehyde (Dialdehyde, DA). The chemical structure, morphology, and surface properties of the PPOP-UOZ-1 were assessed using numerous techniques, including TGA, BET, FT- IR, PXRD, and SEM/EDX. The nominal PPOP-UOZ-1 was then used as an adsorbent for selective (better than 92 %) extraction of Pd(II) from aqueous solutions. The adsorption process was optimized by studying the effect of various factors such as pH, the type and volume of eluent, adsorption and desorption time, and the amount of adsorbent. The results exhibited that the maximum adsorption capacity of PPOP-UOZ-1 for Pd(II) was 208.3 mg/g at a pH of 3.0, based on the Langmuir isotherm model (a determination coefficient of 0.9887). The adsorbent showed excellent selectivity for Pd(II) over other coexisting metal ions, with a recovery rate higher than 92 %. Furthermore, the PPOP-UOZ-1 could be reused for at least six adsorption-desorption cycles without substantial loss of efficiency. This proposed adsorbent and approach was further applicable for the efficient extraction of Pd(II) from environmental water samples.