Recycle of calcium waste into mesoporous carbons as sustainable electrode materials for capacitive deionization

Calcium waste from the direct pyrolysis of calcium citrate salts to produce mesoporous carbons (MCs) were successfully recycled and reused to prepare more MCs, which were used as sustainable electrode materials for capacitive deionization (CDI). Since the discovery of MCs, many attempts were made in their more cost effective synthesis - among these, direct pyrolysis of citrate salts seemed a promising method. However, the sacrificial metal templates (calcium) needed to be dissolved in acid and discharged, a step that wasted precious chemicals and led to higher environment protection cost. Here, for the first time, recycling the calcium waste into MCs and using them as electrode materials for CDI were reported. The recycled MCs showed high surface area, desired mesoporous features, high electrochemical capacitance, and excellent desalting performances, which were comparable to the original MCs. This recycling approach avoided the unnecessary waste of chemicals and improved the cost effectiveness of mass-producing sustainable electrode materials for CM. (C) 2013 Elsevier Inc. All rights reserved.