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Abstract: This paper presents a theoretical analysis of the dynamics of spherical metallic particles in electrostatic separators/purifiers (ESPs). The particle equations of motion are numerically solved in two dimensions using a computational algorithm. The ESPs consist of a pair of conductor cylinder electrodes. The upper cylinder is energized by HVdc, while the lower one is grounded and fixed horizontally on a revolvable axis. Some phenomena and aspects of separation process are explained and depicted including lifting off, impact, “motion collapse” and “sudden bouncing”. The results reveal that the several phenomena depend on initial position, radius and density of the particle, curvature of the cylinder electrodes, distance between the electrodes and amplitude of the applied voltage. Optimization of the parameters is presented in order to get better separation/purification processes. [Copyright &y& Elsevier]

• First-principles calculation was adopted to analyze the electronic structure and optical properties of Ir x Zn 1-x O coatings. • Impurity energy level appeared and gradually increased in ZnO band gap as a number of Zn2+ ions replaced by Ir4+ ions. • IrO 2 nanoparticles covering on ZnO nanorods surface acted as highly efficient electron transfer channels. • Ir 0.09375 Zn 0.90625 O/Ti electrodes with excellent PEC performance and stability. • The PEC degradation mechanism was proposed. Making full use of low-energy photons and reducing photogenerated carriers' recombination rate have been considered important ways to raise photoelectrocatalysis (PEC) efficiency. In this study, Ir-doped ZnO PEC electrodes were prepared by thermal decomposition method, first principles calculations were used to study the effects of Ir content on the electronic structure and optical properties of Ir x Zn 1-x O coatings, the PEC degradation mechanism of the Ir x Zn 1-x O/Ti electrodes was also tentatively presented. The results indicated that with numbers of Zn atoms replaced by Ir atoms, impurity energy level appeared in ZnO band gap, which reduced the electron transition barriers and increased the number of photogenerated carriers. Besides, IrO 2 nanoparticles covered on ZnO nanorods surface, acting as highly efficient electron transfer channels and electrocatalytic active sites, could separate photogenerated electron-hole pairs and enhance PEC performance effectively. PEC performance of Ir x Zn 1-x O/Ti electrodes with different Ir contents under UV irradiation was evaluated by rhodamine B (RhB) removal rate. Compared with pure ZnO electrodes, Ir x Zn 1-x O/Ti ones exhibited much stronger degradation capacity. Specifically, Ir 0.09375 Zn 0.90625 O/Ti electrodes showed the highest degradation rate of 99.4 %, and a relatively high rate of 95.2 % after working 100 h continuously, indicating its excellent long-term stability. [ABSTRACT FROM AUTHOR]