Preparation Of Metal Oxide Composite Materials And The Study On Their Adsorption Properties For Organic Dyes

With the rapid development of industry, dye wastewater pollution is becoming more and more serious. Correspondingly, the treatment of dye wastewater has become an important environmental problem to be solved. Adsorption is one of the most effective and simplest approaches that have been developed for this purpose. Compared with traditional materials, nanomaterial adsorbents have aroused extensive attention of researchers because of their significant advantages. Among all the reported nano adsorbents, aluminum based nanomaterials(Al2O3, AlOOH), carbon materials and magnetic materials stand out due to their own unique properties and advantages. In this paper, the main research contents and results are as follows:1.A hierarchical flower-like γ-Al2O3@C composite was synthesized via a hydrothermal method combined with a heat treatment process using glucose and Al nanopowders as reactants. Herein, glucose plays key roles in the formation of the flower-like structure and carbon shell. Due to the high specific surface area of the flower-like γ-Al2O3@C composite(346.2 m2?g-1), its adsorption ability was investigated. The organic dye Congo Red(CR) was selected as a subject in the study. Over 90% of CR could be removed from aqueous solution within 5 min, and the final adsorption capacity reaches 244.5 mg?g-1 which is much higher than most γ-AlOOH and γ-Al2O3@C materials reported before, indicating it would be a promising material used in the water treatment industry.2.On the basis of the as-prepared hierarchical flower-like γ-Al2O3@C composite, we introduced magnetic nanoparticles to achieve magnetic separation and simplify recycling. γ-Al2O3@C/FeCo composite was successfully prepared by a simple room temperature reduction process, and applied in the adsorption of organic dye Orange II. The influence of the different mole ratio of Fe/Co on the absorption performance of γ-Al2O3@C/FeCo composite was also studied. The results showed that the γ-Al2O3@C/Fe0.32Co0.68 composite possessed the best adsorption ability, and the final adsorption capacity reaches 933.9 mg?g-1. Compared with FeCo composite and γ-Al2O3@C composite, the absorption performance of γ-Al2O3@C/FeCo composite was significantly improved.3.A facile solvothermal method was used to synthesize Fe3O4 crystals. In the solvothermal synthesis process, the effect of NaOH dosages from 0.3 to 4.0 g on the morphology evolution(from nanoparticles to octahedra) of Fe3O4 crystals was carefully researched. Meanwhile, the growth process of Fe3O4 crystals at different reaction time was also recorded. Furthermore, it is found that the particle sizes and crystallinity of Fe3O4 crystals can be controlled by the dosages of NaOH. In this paper, the increase of both reaction time and NaOH concentrations is a minimization process of surface energy for Fe3O4 crystals. During the synthesis process, the addition of N2H4?H2O and ethylene glycol not only facilitates the narrow distribution of particle sizes but also contributes to the formation of incontinuous multicavities of about 5 nm in the magnetite.