To date, particle separation using dielectrophoresis (DEP) has been intensively investigated for small-scale operations mainly for bioapplications and nanoapplications. However, methods for expanding a DEP separator to large scale have not yet been established. In this study, an easily expandable wetted-wall DEP separator is proposed, and experiments to capture TiO2 particles in ethanol and separate TiO2 from a mixture with SiO2 are conducted. During the separation of TiO2 from the mixture with SiO2, the selectivity for capturing TiO2 reached about 90%; however, admixing of SiO2 negatively influenced this selectivity. Based on the experimental results, several equations are proposed to correlate the operating conditions with the saturated amount of TiO2 captured by this separator. Since scaling up of the present separator can be conducted based on numbering up, the proposed equations for predicting the amount of particles captured per electrode pair will be useful for estimating the required separator size.