Abstract: Sodium hypochlorite and synthesized sodium trititanate nanorods (Na₂Ti₃O₇, 186 nm×1270 nm) were used as the oxidant and adsorbents for in situ oxidative adsorption treatment of actual electroplating wastewater containing Cr(VI) (2.6-5.2 mg·L^-1), Cu²⁺ (2.7-5.4 mg·L^-1), and Ni²⁺ (0.2705-0.541 mg·L^-1) ions at pH of 8.8-9.1 and 20-60 ℃. The as-synthesized sodium trititanate nanorods were characterized by XRD, HRTEM, N₂ adsorption/desorption, SEM, EDX, and zeta potential techniques. The concentrations of heavy metal ions in wastewater were analyzed by ICP technique. After in situ oxidative adsorption treatment under the concentrations of 25 g·L^-1 for sodium hypochlorite and 125 mg·L^-1 for sodium trititanate nanorods at 60 ℃ for 5 h, the heavy metal ion concentrations could be reduced from initial value of 2.6 to final value of 1.92 mg·L^-1 for Cr(VI), 3.6 to 0.17 mg·L^-1 for Cu²⁺, and from 0.2705 to 0.097 mg·L^-1 for Ni²⁺, respectively. Cr(VI), Cu²⁺ and Ni²⁺ ions could be effectively removed by the in situ oxidative adsorption method. The in situ oxidative adsorption processes of Cr(VI), Cu²⁺ and Ni²⁺ ions are satisfactorily simulated by the pseudo-second order adsorption kinetics and Langmuir adsorption isotherm, respectively. Adsorption thermodynamics analyses reveal that the oxidative adsorption processes of Cr(VI), Cu²⁺ and Ni²⁺ ions are spontaneous and endothermic. The oxidation degree of metal-contained complexes influences the values of thermodynamics functions.

Key words: Heavy metals, Oxidative adsorption, Electroplating wastewater, Sodium trititanate nanorods, Nanomaterials, Oxidation

摘要： Sodium hypochlorite and synthesized sodium trititanate nanorods (Na₂Ti₃O₇, 186 nm×1270 nm) were used as the oxidant and adsorbents for in situ oxidative adsorption treatment of actual electroplating wastewater containing Cr(VI) (2.6-5.2 mg·L^-1), Cu²⁺ (2.7-5.4 mg·L^-1), and Ni²⁺ (0.2705-0.541 mg·L^-1) ions at pH of 8.8-9.1 and 20-60 ℃. The as-synthesized sodium trititanate nanorods were characterized by XRD, HRTEM, N₂ adsorption/desorption, SEM, EDX, and zeta potential techniques. The concentrations of heavy metal ions in wastewater were analyzed by ICP technique. After in situ oxidative adsorption treatment under the concentrations of 25 g·L^-1 for sodium hypochlorite and 125 mg·L^-1 for sodium trititanate nanorods at 60 ℃ for 5 h, the heavy metal ion concentrations could be reduced from initial value of 2.6 to final value of 1.92 mg·L^-1 for Cr(VI), 3.6 to 0.17 mg·L^-1 for Cu²⁺, and from 0.2705 to 0.097 mg·L^-1 for Ni²⁺, respectively. Cr(VI), Cu²⁺ and Ni²⁺ ions could be effectively removed by the in situ oxidative adsorption method. The in situ oxidative adsorption processes of Cr(VI), Cu²⁺ and Ni²⁺ ions are satisfactorily simulated by the pseudo-second order adsorption kinetics and Langmuir adsorption isotherm, respectively. Adsorption thermodynamics analyses reveal that the oxidative adsorption processes of Cr(VI), Cu²⁺ and Ni²⁺ ions are spontaneous and endothermic. The oxidation degree of metal-contained complexes influences the values of thermodynamics functions.

关键词: Heavy metals, Oxidative adsorption, Electroplating wastewater, Sodium trititanate nanorods, Nanomaterials, Oxidation