High-efficiently capturing trace thallium (Ι) from wastewater via the prussian blue@polytetrafluoroethylene hybrid membranes

Abstract

The exploitation of advanced material technology with high selectivity, efficiency, and separability for thallium (Tl) removal remains challenging. In this work, a hybrid polytetrafluroethylene membrane with polydopamine (PDA)/polyethyleneimine (PEI) co-supported Prussian blue nanoparticles (PB NPs) was successfully fabricated and denoted as PB@PDA/PEI-M−1. The PB@PDA/PEI-M−1 displayed a high-efficient capture for Tl(I) during a continuous flowing operation. Based on the pseudo-second-order model, its dynamic Tl(I)-adsorption constant (k) and maximum capacity (qe) are 1.8 min−1 and 460.4 mg/m2 respectively, which are both much higher than the static adsorption and many previous studies. Tl(I)-adsorption capacity of PB@PDA/PEI-M−1 was slightly decreased by the disturbances of many accompanying impurity ions (H+, Ca2+ or Mg2+), but it still reached a high level. The density functional theory (DFT) revealed the most prominent binding ability of membrane surface-loaded PB with Tl(I) via ion exchanges, contributing to the high selectivity of PB@PDA/PEI-M−1 in capturing trace Tl(I). As for the macromolecular organic matter, humic acid (HA) facilitated the Tl(I)-capture ability of PB@PDA/PEI-M−1 due to the formation of Tl-HA complexes and their high adsorption on membrane surface. By virtue of those advantages, our as-prepared membranes exhibit excellent ability in remedying the actual Tl(I)-polluted pearl river water, and in the meantime, membrane structure robustness was well maintained. All results verified that PB@PDA/PEI-M−1 provided a feasible technology for Tl(I) removal in a complicated environment.