Incorporation of composite metal-PVP derived carbon membranes for the percrystallisation of salt water

In this research using supported metal‑carbon membranes in a membrane percrystallisation application, we investigated the influence of metal ions on the formation of carbon during carbon membrane synthesis by combining polyvinylpyrrolidone (PVP) with various metal compounds, including zinc, potassium, barium, sodium, magnesium, calcium, and strontium, through calcination at 700 °C in a nitrogen atmosphere for the first time. These carbon membranes were then subjected to continuous percrystallisation experiments to produce dry salt crystals from salt solutions. The feed solution (3.5, 10, 20 wt% of salt) were used at 30, 50, and 70 °C for the performance evaluation. Intriguingly, the addition of metal elements to the PVP solution resulted in an enhancement in the total pore volume and surface area of the resulting carbon membranes. The PVP-Zn precursor exhibited the highest increase with a maximum improvement of 99 fold. Moreover, when compared to the PVP membranes alone, the composite membranes also exhibited higher fluxes. Among the tested composite carbon membranes, PVP-Ca, PVP-Zn, and PVP-Mg demonstrated the highest flux values, reaching an impressive 55 kg.m−2.h−1. Additionally, these membranes exhibited self-elimination, where salt was effectively removed from the membrane surface during percrystallisation testing. Thus, these membranes have the potential to be employed in desalination applications.