Walnut shell-derived porous carbon with MgSO4 modification for high-performance capacitive deionization

Capacitive deionization (CDI) is considered as a promising desalination technology, and the fabrication of electrode materials with high specific surface area, good hydrophilicity and hierarchical pore structure is beneficial to improve CDI performances. Herein, porous carbon (MAWC-700) with a high specific surface area of 3074.8 m2 g−1 and superior hydrophilicity is derived using walnut shell as precursor, KOH as activation agent, and MgSO4 as modification. The MAWC-700 demonstrates a capacitance of 214.3 F g−1 at 5 mV s−1, and the corresponding CDI delivers a high desalination capacity of 27.79 mg g−1 and salt adsorption rate of 5.56 mg g−1 min−1 at 1.2 V. Hence, the synthesis of biomass-based porous carbon activated with KOH along with MgSO4 is an effective way to improve desalination performances for CDI applications.