Chemical separation processes, including water purification, carbon capture, and critical mineral recovery, account for up to 15% of global energy use yet remain highly inefficient. My research tackles this grand challenge by using acidity, measured in pH, as a master control knob to drive chemical separations with far less energy consumption. We will develop a new class of polymeric buffers that reversibly shift solution acidity in response to mild heating, eliminating the high temperatures required in current industrial separation processes. We will combine experiments with thermodynamic calculations and machine learning to map how the molecular structure of buffers governs pH regulation and separation outcomes. Our work will transform pH-swing technology from an energy-intensive process into a low-cost and sustainable solution powered by sunlight or waste heat, accelerating our ability to address climate change and global resource security.