| Various by-products containing aluminum element are produced in the modern chemical production process, they has low utilization and the amount of them is enormous. Not only is a great pollution of the environment, but also a tremendous waste of limited resources without take full advantage of them. Therefore, we can convert them into high value-added, wide range of applications of activated alumina products through various means. At the same time, serious environmental problem was rised with the rapid development of the economy poses, water scarcity has become the most pressing problems facing humanity, waste-water treatment and purification are also imminent.Alumina oxide is an important kind of chemical material in modern industrial development. It is widely used in chemical, petrochemical, natural gas and fertilizer industry as adsorbents, drier catalysts and catalyst supports. Thus, it is necessary to make full use of aluminum industrial flotsam to produce high value-added activated alumina and applied to the purification of industrial waste-water. Not only make the effective use of resources, but also the great help to reduce emissions and maintain the ecological environment.In this paper, the inorganic aluminum salt- sodium aluminate tetrachloride from the industry flotsam is used as raw material. Firstly, aluminum chloride hexahydrate was obtained through washing with ethanol aqueous, then α-boehmite was obtained with adding ammonia by the proposed method pseudo boehmite.Secondly, α-boehmite was putted into the oil ammonia column for aging. Finally, spherical porous activated alumina was obtained by calcination process. Methyl orange was used as simulated waste-water to verification the industrial waste-water treatment capacity of activated alumina which was produced before. Many factors impact on the preparation of porous alumina oxide was investigated, such as the reaction temperature, the reaction solution p H, concentration of reactants, whether added PEG(polyethylene glycol), the time when to add PEG, whether added EDTA and the different amounts of EDTA, and calcination temperature. Finally, the optimum conditions was determined: the reaction temperature is 60 oC, the reaction solution p H = 7, the reactants(trihydrate aluminum chloride) concentrations of 51.3 mg/m L, adding PEG make big holes distribution increase. Hierarchical porous alumina was characterized by XRD, SEM and nitrogen adsorption-desorption isotherms and other methods. The results showed that: the specific surface area of resulted activated alumina prepared from sodium aluminum tetrachloride(without modification) was 173m2/g, pore volume can reach 1.34cm3/g, a large pore size distribution(greater than 100nm) above 50%. the surface area increased by PEG modification and other excellent features was improved: the surface area and pore volume of the activated alumina particles increased slightly after the addition of PEG. Aperture ratio of 100 nm or less increase to a certain extent, at the same time, the distribution of more than 100 nm will be reduced. The specific surface area of that activated alumina which was modified by EDTA(Ethylenediamine tetra-acetic acid) was significantly increased, the sample which was modified by 6mol% EDTA has the highest surface area of 320m2/g.Activated alumina and activated carbon was compared using adsorption capacity of methyl orange as indicator, the following results was obtained: 1) Adsorption of methyl orange volume by activated alumina and activated carbon increased with the adsorb time extented. 2) Change the initial concentration from 300mg/L to 2500mg/L, the equilibrium adsorption capacity was increased from 40mg/L to about 260mg/L, the rate of increase gradually decreased; concentration continues to increase, when it reaches 3000mg/L, only a slight increase in the amount of equilibrium adsorption. 3), Adsorption of methyl orange by activated alumina gradually increased with adsorb time; adsorption rate decreases with adsorb time, then the equilibrium state was reached after 170 h. 4) Adsorption capacity of methyl orange by activated alumina was relatively high at a p H in the range of 3-11, which proved that the activated alumina that produced by tetrachloro sodium alumina has a widely range of p H adaptation. 5) As the temperature increases(from 30 oC to 50oC), adsorption amount gradually increases(from 100mg/g to 180mg/g). Thus, the alumina oxide has a strong treatment capacity on simulated waste-water that simulated by methyl orange, it can be used as adsorbents to apply in industry. |
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