Once a membrane candidate was secured, the following step was optimizing filtration performance as a function of operating pressure and input flow rate. As the Zaiput cell was limited to 20 bar maximum pressure, a new cross-flow cell was designed in-house to achieve pressures up to 40 bar (operating limit for the NF030306, according to its specifications). The cell design is detailed in Supplementary Information, Section 2.6. Figure in Supplementary Information presents the results of the screening of operating pressures of TBADT recovery with nanofiltration. As expected, higher pressures resulted in an increased flux without significantly affecting TBADT recovery. However, at 40 bar, undesired TBADT precipitation occurred, leading to decreased catalyst concentration in the retentate solution and, thus, reduced catalyst recovery. For this reason, an operating pressure of 35 bar was selected for further experiments. Figure in Supplementary Information details the screening of flow rates. Longer residence times in the cell resulted in increased transport across the membrane. However, a decreased flux was observed for the lowest flow rate, which can be explained by reduced mixing in the cell and concentration polarization across the membrane. Therefore, the flow rate for catalyst recovery was maintained at 0.15 mL/min. The result of the membrane screening and operating parameters optimization proved the potential of OSN for TBADT recovery, with an achieved recovery exceeding 98%.