Evaluation of the optimal activation parameters for almond shell bio-char production for capacitive deionization

A study on a possible new biomass waste to be used as electrode material for capacitive deionization (CDI) processes was performed. Raw almond shells were pyrolyzed at 800, 900 and 1000 °C and then activated through CO2. Carbon activation is used to develop porosity inside the material, increasing the specific surface area and the adsorption performances. In this work, authors tried to correlate the effects of pyrolysis and activation temperature on the ion storage capacity. Results from the desalination tests indicated that the best performance in terms of ion adsorption was obtained when the bio-char was activated at the temperature of 900 °C. Brunauer-Emmet-Teller (BET) and Barret-Joyner-Halenda (BHJ) analysis confirmed the trend of the CDI tests, reporting the highest surface area and share of micropore sites for the 900 °C samples. Salt adsorption capacity was found to be in the range of 13.7 to 19.2 mg g−1.