Carbon dioxide activated carbonized date palm fronds free standing electrodes for highly efficient capacitive deionization of water

Water is essential for life and is one of the most important resources on Earth. However, pollution of water is a major concern, as it can have negative impact on both the environment and human health. Capacitive deionization (CDI) of water is being considered as one of the emerging water purification techniques for removal of ions and desalination. In this work, CDI performance of free-standing electrodes made of CO2 activated carbon nanoparticles (AcNP) has been studied. These nanoparticles were produced from carbonized date palm fronds followed by ball milling. The AcNP were mixed with single wall carbon nanotubes and polymer binder; subsequently casted on glass substrate to fabricate highly conducting free-standing electrodes. The Brunauer–Emmett–Teller analysis of the AcNP in contrast to the un-activated carbon nanoparticles (UnAcNP) showed significant increase in the specific surface area, microspore and mesopore volume, total pore volume and average pore size. The specific capacitance values of the UnAcNP and AcNP electrodes were measured to be 8.75 and 50 Fg−1, respectively at a fixed scan rate of 5 mV/s. The electrochemical impedance spectroscopy measurement also showed that the CO2 activation has reduced the charge transfer resistance of the fabricated electrode and enhanced its capacity. The CDI performance showed that the AcNP has a much higher salt absorption capacity of 6.30 mg/g in contrast to 0.032 mg/g for the UnAcNP sample. Moreover, average salt absorption rate was found to be 0.42 mg/g/min for AcNP in comparison to UnAcNP (0.0021 mg/g/min). The higher desalination capacity of the AcNP shows promising applications of plant-based carbon materials in water desalination and purification systems.