Urea‐ and thiourea‐engineered sugarcane bagasse carbon aerogel for selective NaCl/NaHCO3 adsorption in MCDI

Abstract Background Cellulose aerogel was fabricated from the high‐purity cellulose recovered from sugarcane bagasse together with crosslinking agents such as thiourea and urea. Subsequently, the cellulose aerogel samples were carbonized and activated to form carbon aerogel, which was then processed into porous carbon aerogel electrodes to be utilized in a membrane capacitive deionization (MCDI) device for NaCl and NaHCO 3 adsorption. Results Among the fabricated electrodes, the porous carbon aerogel electrode derived from sugarcane bagasse and thiourea (SB‐TCCA) exhibited superior electrochemical and adsorption properties. It possessed a large BET surface area of 1003.1 m 2 g −1 , leading to a high specific capacitance of 72.10 F g −1 at a scan rate of 5 mV s −1 . This resulted in an outstanding NaCl adsorption capacity of 48.78 mg g −1 at an applied potential of 1.8 V. Furthermore, the SB‐TCCA electrode demonstrated a strong preference for NaHCO₃ adsorption, with an mSAC_NaHCO₃ of 61.97 mg g −1 at 1.6 V. In assessing selectivity between NaHCO₃ and NaCl using a solution containing 200 ppm NaHCO₃ and 400 ppm NaCl, the SB‐TCCA electrode demonstrated superior performance for HCO 3 − ions, achieving an mSAC_NaHCO 3 of 50.46 mg g −1 (0.601 mmol HCO₃ − ), which was 3.38 times higher than that of NaCl (10.40 mg g −1 or 0.179 mmol Cl − ). Conclusion These results indicate that the synthesized carbon aerogel not only exhibits excellent desalination performance but also holds potential for CO₂ adsorption, making it a promising material for MCDI applications. © 2025 Society of Chemical Industry (SCI).