A fluorine/nitrogen-co-doped titania/activated carbon (F-N/TiO2/AC) composite has been prepared through an immersion-hydrothermal method. Magnetic activated carbon (MAC) has been prepared through a chemical coprecipitation method and used to assemble the analogous composite F-N/TiO2/MAC. The characterization results show that F-N/TiO2/MAC contains a certain amount of magnetic ferrous oxide material, and the presence of magnetic ferrous oxide material will not affect the crystalline shape of TiO2. F-N/TiO2/MAC is a weak magnetic material, and it could be conveniently recycled by applying a strong magnetic field. Methyl orange solution has been used as a target to assess the photocatalytic degradation and recycling performances of the composites. Results show that the adsorption of methyl orange on the photocatalysts follows a pseudo second-order kinetic model, and the adsorption rate of F-N/TiO2/AC is higher. In the photocatalytic degradation of methyl orange pseudo first-order reaction kinetics study, the k value of F-N/TiO2/MAC was 0.00497 min(-1), which was higher than that of F-N/TiO2/AC. Even though the adsorption performance of F-N/TiO2/MAC is not as good as that of F-N/TiO2/AC, its photocatalytic degradation performance is superior. Overall, the two composite materials show roughly the same removal efficiencies for methyl orange, reaching 100 % for F-N/TiO2/AC and 98.9 % for F-N/TiO2/MAC. In terms of recycling performance, the magnetic property of F-N/TiO2/MAC makes it easier to recover from mixed solutions.

A novel composite photocatalyst loading titanium dioxide particles onto activated carbon and co-doping with fluorine and nitrogen (F-N-TiO2/AC) was synthesized using the impregnation-hydrothermal method for the degradation of printing and dyeing wastewater. The optimal preparation conditions of the composite photocatalyst were determined using orthogonal ex-periments. Through range analysis and variance analysis, the optimal preparation conditions were as follows: a molar ratio of anhydrous ethanol, glacial acetic acid, and tetrabutyl titanate of 3:175:100, and hydrothermal temperature of 150 degrees C and hydrothermal time of 12 h. The cata-lyst prepared under these conditions showed high catalytic activity, with 100 % degradation of methyl orange when irradiated with a xenon lamp light source for 60 min, and the preparation conditions were feasible. The F-N-TiO2/AC composite photocatalysts were characterized using x-ray diffraction and nitrogen adsorption-desorption measurements. On the basis of this analy-sis, it was found that the doping of fluorine and nitrogen did not change the anatase structure of titanium dioxide but affected the grain growth and changed the structural properties of the F-N-TiO2/AC photocatalyst. Good reusability properties were also found.

In the paper, a novel method to improve the uniformity of the temperature distribution on the surface of the hot-plate is presented. Firstly, the effect of magnetic flux density under coupling of the electromagnetic and heat transfer on target surface temperature is studied numerically by using the commercial simulation software COMSOL Multiphysics. To evaluate the uniformity of the temperature distribution on the target surface, the temperature nonuniformity index on the target surface was firstly employed in terms of a specific designed electric coil. Secondly, the principal components analysis combined with the orthogonal test method is employed to analyze the shape parameters and obtain optimized temperature distribution at the target surface of the hot-plate. The simulated results show that the uniformity of temperature can be greatly improved by appropriately adjusting distribution of magnetic flux and the uniform temperature distribution can be achieved on a heating surface of 130 mm in length, 130 mm in width, and 30 mm in height. Finally, the optimizations of target surface temperature on hot-plate with different target temperatures were studied as well.