Fabrication And Adsorption Performance Of Hierarchical Boehmite Composite Nanomaterials

In the work, walnut-like, leaf-like and cabbage-like hierarchical structures γ-AlOOH and three kinds of composite nanomaterials including walnut-like γ-AlOOH/graphene, cabbage-like γ-AlOOH/graphene, γ-AlOOH/α-Fe2O3 were successfully prepared through a template-free hydrothermal method. In addition, the morphology and structure of the materials were characterized and the adsorption properties towards organic dyes and heavy metal ions were also investigated. The main researches are summerized as followed:1. Monomorphology, uniform, and walnut-like, leaf-like and cabbage-like hierarchical structures γ-AlOOH were synthesized via hydrothermal methods with different reaction conditions by using Al(NO3)3?9H2O as aluminum source and urea as homogeneous precipitation agent. The result shows: three hierarchical structures are self-assembled by nanofibers. And the maximum adsorption capacity for Cr(VI) of leaf-like, walnut-like and cabbage-like γ-AlOOH is 7.4mg/g, 32.16mg/g and 14.36mg/g, respectively; maximum adsorption capacity for methyl orange is 59.9mg/g, 97.15mg/g and 84.93mg/g, respectively; maximum adsorption capacity for Congo red is 99.0mg/g, 98.8mg/g and 258.02mg/g, respectively.2. By one-pot hydrothermal method, the walnut-like γ-AlOOH/graphene nanocomposites were successfully prepared. The result demonstrates that when the addition amount of graphene is 1% and 2.5%, the resulting products were the composites combining hierarchical structure γ-AlOOH with grapheme. Walnut-like γ-AlOOH/graphene composite materials containing 1% graphite have best adsorption properties for Cr(VI) and Congo red, and maximum adsorption quality was 41.74 mg/g(pH=2) and 99.2mg/g, respectively. This results are higher than the single-phase γ-AlOOH for Cr(VI)(35.86 mg/g, pH=2) and Congo red(97.15mg/g).3. By one-pot hydrothermal method, the cabbage-like γ-AlOOH/graphene nanocomposites were successfully prepared. The result indicates that cabbage-like γ-AlOOH/graphene composite materials containing 1% graphite has best adsorption properties for Cr(VI), and maximum adsorption quality is 17.32mg/g(pH=2). It’s higher than the single-phase γ-AlOOH for Cr(VI)(14.61mg/g, pH=2); Composite materials containing 2.5% graphite has best adsorption properties for acid chrome blue K, and maximum adsorption quality is 99.69 mg/g. It’s higher two times than the single-phase γ-AlOOH for acid chrome blue K(54.09mg/g). Meantime, this two different composites show excellent adsorption properties for Congo red.4. γ-AlOOH/α-Fe2O3 nanocomposites were synthesized by one-pot hydrothermal method. The result manifests that with the increasing of urea molar and the less of molar ratio of the aluminum source/iron source in reaction system, the percentage of α-Fe2O3 phase in the composites increases. When the molar amount of urea is 28.8 in resultant reaction system, adsorption performance of resulting nanocomposites for acid chrome blue K and Congo red is best, the maximum adsorption mass of 42.92 and 99.19mg/g respectively. The resulting composite materials under the molar ratios of aluminum/iron source is 2: 1 and 10: 1 in the reaction system for acid chrome blue K and Congo red get most excellent adsorption properties. The maximum adsorption mass is 65.09mg/g and 99.19mg/g, which are better than the adsorption properties of single-phase γ-AlOOH and single-phase α-Fe2O3.