TiO2/Activated Biochar Hybrid Material Prepared By Ultrasonication and Heat Treatment for Capacitive Deionization

Abstract

TiO2-doped activated biochar was successfully prepared as a hybrid electrode material for capacitive deionization. The introduction of TiO2 has the advantages of low cost, high chemical stability, hydrophilicity, and eco-friendliness. Activated biochar was treated with titanium isopropoxide (TTIP) and isopropyl alcohol solution by an ultrasound assisted process followed by calcination at 400 °C. The physical and chemical properties of the resulting material was characterized by XPS, XRD, SEM, and TEM. Cyclic voltammetry was performed to analyze the electrochemical properties of the prepared electrodes. Furthermore, the performance of TiO2-biochar electrode was evaluated in a 3D-printed CDI cell and the salt removal capacity was examined using a chloride ion-selective electrode. It was shown that the removal capacity was enhanced from 5.1 mg/g NaCl (activated biochar) to 8.6 mg/g NaCl. The increase in capacity is associated with a better wettability of the electrode, which increases the number of surface-active sites and promotes a more efficient ion diffusion inside the biochar pores. This result is beneficial to improve biochar application as an inexpensive alternative electrode material with metal oxide modification.