Removal of heavy metals from aqueous solutions by high performance capacitive deionization process using biochar derived from Sargassum hemiphyllum

Abstract

Capacitive deionization (CDI) has been considered as an efficient, energy-saving and environmental friendly technology for water treatment. For the practical application of CDI, high-performance electrode materials beyond standard activated carbon should be developed. In this study, biochar derived from brown algae Sargassum hemiphyllum prepared by pyrolysis at 300–700 °C and then used as the CDI electrode to remove Cu(II) from aqueous solutions. According to the findings, the optimal pyrolysis temperature was 700 °C, and the electrosorption capacity of BAB700 was 75–120 mg·g−1 at an applied voltage of 1.2 V across wide range of initial pH, temperatures and ion types. Moreover, BAB700 also exhibited outstanding ability to electrosorb other heavy metals (Zn(II), Ni(II), and Cd(II)). In addition, the BAB700 retained the Cu(II) removal efficiency of 70 % in 10 cycles. Cu(II) in actual water is completely eliminated with great reproducibility, resulting in a high degree of applicability for water treatment.