Polycations inclusion to simultaneously boost permeation and selectivity of two-dimensional TaS2 membranes for acid recovery

Abstract

Two dimensional (2D) TaS2 laminates have highly regular and ordered transfer mass channels, thus being promising acid recovery membrane candidates for diffusion dialysis (DD) applications to discern H+ and metallic ions. However, it remains a daunting task to get access to high-performance 2D acid recycling membranes made from single TaS2 nanosheets. Here, we report manipulation of the chemical environments of TaS2 channels to develop excellent acid recycling 2D membranes. As demonstration projects, positively charged poly(diallyldimethylammonium chloride) (PDDA) and poly(4-vinylpyridine) (P4VP) in acid solution were chosen as polycation intercalators to modify the TaS2 2D channels. Under the DD mode, the TaS2 membrane exhibits a H+ dialysis coefficient (UH+) of 3.72 × 10−3 m h−1 and separation factor (S) of 9 towards the simulated acid pickle. In contrast, the UH+ and S value of the PDDA@TaS2 membrane improve to 12.7 × 10−3 m h−1 and 34.4 respectively. Those of the P4VP@TaS2 membrane increase to 12.5 × 10−3 m h−1 and 29.1 respectively. The reported acid recovery properties of PDDA@TaS2 and P4VP@TaS2 membranes exceed the commercial DF-120 acid recovery membranes. The experiment and simulation results reveal that the synergistical enhancements of UH+ and S originate from the incorporating polycations in PDDA@TaS2 and P4VP@TaS2 composite channels.