Nanofiltration (NF) membranes have the potential to significantly advance resource recovery efforts where monovalent/divalent ion separation is critical, but their utilization is limited by inadequate stability under extreme conditions. "Base separation"-i.e., separating hydroxide from other ions-has emerged as an essential approach in resource recovery, enabling the extraction of multivalent anions (e.g., carbonates and phosphates) from hydroxide-rich streams. There is a particularly high demand for membranes capable of separating carbonates from hydroxide-rich CO