“…Conventional methods for removing metal ions include electrochemical and chemical precipitation, ion exchange, membrane separation, coagulation–flocculation, adsorption, and capacitive deionization (CDI) (Ali et al., 2011; Fan et al., 2016; Hering et al., 1997; Mossad and Zou, 2012; Shin et al., 2011). Among these, the CDI technique is widely used because it offers simple operation, low cost, high efficiency, and no secondary pollution (Demirer et al., 2013; Hemmatifar et al., 2016; Wang et al., 2016).…”