| Currently, problems of water environmental pollution ha ve become increasingly serious. Based on the advantages of large specific surface areas and unique pore structures of mesoporous carbons and easy solid-liquid separation of magnetic nanoparticles, a novelly magnetic order mesoporous carbon with cobalt nanoparticle(Co/OMC) was successfully prepared to efficiently remove Rhodamin B from aqueous solution. The adsorption mechanism was thoroughly discussed and the application of Co/OMC in industrial effluents treatment was investigated.In this study, Co/OMC was prepared using impregnation method. Specifically, ordered mesoporous silica SBA-15 was firstly synthesized by traditional hydrothermal synthesis method. Then, SBA-15 used as the template, sucrose as the carbon source, under the condition of strong acid, ordered mesop orous carbon(OMC) was prepared through thermal polymerization and carbonization. Follow on it, OMC used as the supporter, cobalt nitrate as the metal source, cobalt nanoparticles were embedded on the OMC via impregnation and thermal polymerization. Thus, the synthesis of magnetic order mesoporous carbon with cobalt nanoparticle(Co/OMC) was completed. The SEM and TEM images indicated that ordered mesoporous carbons presented rodlike structure, and each stripe was arranged orderly. Dark cobalt nanoparticles were evenly dispersed onto the surface of OMC. After functionalization with cobalt nanoparticles, the pore size became smaller, which was centered near 4.3 nm. The surface area was reduced to 955.3 m2/g, and the degree of graphitization of the mesoporous adsorbent increased. The saturation magnetization strength for Co/OMC was 2.9 emu/g, which was beneficial to magnetic separation. Batch tests were conducted to investigate the adsorption performance. The adsorption capacity of the resultant adsorbent was relatively high compared with raw ordered mesoporous carbon(OMC) and reached an equilibrium value of 468 mg/g at 200 mg/L of initial Rhodamin B concentration. Removal efficiency for Rhodamin B even reached 96% within 25 min at 100 mg/L of initial Rhodamin B concentration. Besides, the adsorption amount increased with the increase of solution p H, adsorbent dose and initial Rhodamin B concentration. Kinetics study showed that the Rhodamin B adsorption agreed well with pseudo-second-order model(R2=0.999) and had a significant correlation with intra-particle diffusion model in the both two adsorption periods. Furthermore, thermodynamics research indicated that the adsorption process was endothermic and spontaneous in nature, and during the adsorption, the randomness at the solid-liquid interface augmented. The adsorption isotherms fitted well with Langmuir model, demonstrating the formation of mono-molecular layer on the surface of Co/OMC during adsorption process, and each adsorption site possessed equal potential energy. What is more, the regeneration test confirmed the excellent regenerative ability of the adsorbent, and the adsorption capacity of Co/OMC was still high, with above 83% of Rhodamin B removal efficiency in the seventh regeneration cycle. The above results confirmed that Co/OMC has the potential superiority in removal of Rhodamin B from aqueous solution. |
