A new magnetic CuO@Fe 3 O 4 nanocomposite was fabricated through an impregnation method and then characterized through X-ray diffraction, high-resolution transmission electron microscopy, nitrogen adsorption-desorption, and energy dispersive X-ray spectroscopy. The effects of initial solution pH, catalyst addition, reaction temperature, target contaminant, and persulfate (PS) concentration on 2,4-dichlorophenol (2,4-DCP) degradation in the activated PS system with the composite was evaluated. Results showed that the composite can degrade 96.9% of 2,4-DCP after 180 min under the following reaction conditions: PS, 10 mM; CuO@Fe 3 O 4 , 0.624 g L À1 ; 2,4-DCP, 100 mg L À1 ; pH, 6.8 AE 0.3; and temperature, 30 C. Quenching tests of different scavengers revealed that SO 4 c À and cOH are responsible for 2,4-DCP degradation. The pseudo-first-order kinetic model was then established to describe 2,4-DCP mineralization.The composite also exhibited stable catalytic performance after using for three cycles, thereby indicating the promising application of the catalyst for remediation of water contaminated with 2,4-DCP.Comparative experiments were carried out on PS, CuO@Fe 3 O 4 , and PS/CuO@Fe 3 O 4 systems to determine the effects of the synthesized CuO@Fe 3 O 4 composites on PS activation for 2,4-DCP degradation. These experiments were conducted in the same reactor and controlled under the same operating conditions. The results are shown in Fig. 2(a). Without PS, 2,4-DCP can stably exist in the presence of the catalysts for 180 min. In the control group with PS only, about 4% of 2,4-DCP was removed from the solution over the same time period. Accordingly, the addition of 0.624 g L À1 CuO@Fe 3 O 4 composite to PS solution resulted in rapid and pronounced degradation of 2,4-DCP, with 96.9% removal during the 180 min reaction time, compared with the addition of the CuO@Fe 3 O 4 composites and PS only. Comparatively, 0.928 g L À1 Fe 3 O 4 (0.004 mM Fe(II)) equal to 0.624 g L À1 CuO@Fe 3 O 4 (0.002 mM Fe(II) + 0.002 mM Cu(II)) removed 8.1% 2,4-DCP in the existence of PS. It agrees with previous reports. 37 These data indicate that sulfate free radicals can be efficiently produced by combining activated PS with the CuO@Fe 3 O 4 composite to oxidize 2,4-DCP. The effect Fig. 1 Characterization of catalysts. (a) XRD pattern. (b) Magnetization curves measured at room temperature for the synthesized CuO@Fe 3 O 4 composites before (solid line) and after three reaction cycles (dash line). (c) Nitrogen absorption/desorption isotherms and pore size distribution curve (the inset pattern). (d) EDX spectra and component molar ratio of the composites. (e) HRTEM images. 57062 | RSC Adv., 2015, 5, 57058-57066 This journal is

Magnetic nanoscaled ascorbic acid/magnetite (H2A/Fe3O4) composite was prepared by oxidative polymerization and proposed as a novel heterogeneous catalyst of persulfate (PS) for improved degradation of 2,4-dichlorophenol (2,4-DCP).

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