Fig. 7. Preparation and performance of large-area membranes and modules.

a An optical image of a large-area QSPIP-TMC membrane, b nanofiltration performance of five pieces of small membranes (M₁-M₅, 8 × 8 cm²) randomly selected from the membrane in (a). M₀ is the small membrane in Fig. 3b. Test conditions: 1000 ppm MgCl₂, 6 bar. c Schematic structures (top) and photographs (bottom) of QSPIP-TMC modules prepared from the membrane in (a). The optical image of d feed solution (salt concentration: 5.78 g/L, Mg²⁺/Li⁺ ratio: 40) and e three-stage nanofiltration. Please note: the feed solution was prepared to simulate the salt concentration and Mg²⁺/Li⁺ ratio in the East Taijinar Brine⁶¹. f Effect of operation time in the volume of permeates of 1st, 2nd, 3rd-stage nanofiltration. g The Mg²⁺/Li⁺ ratio of feed and permeates in 1st, 2nd, 3rd-stage nanofiltration. h The mass content of Li₂CO₃ and MgCO₃ in the Li₂CO₃ compound. The insert is the optical image of Li₂CO₃ compound.