Adsorption Of Contaminations From Aqueous Solutions By Activated Alumina

Activated alumina is a kind of material with porous structure, which is widely used in the adsorption and removal of various pollutants. Industrial activated alumina adsorbents’specific surface areas and pore volumes are relatively small, adsorption capacities of various contaminants are low, and the regeneration performance needs to be improved. It may cause great influence on the industrial application of activated alumina for adsorption.In this study, we used lab-made boehmite with large specific areas, pore volumes and pore diameters to prepare activated alumina Lab-6 at 500℃ for 2h for the adsorption of Congo red from aqueous solution. The adsorption capacity of Lab-6 for Congo red was 737.60mg/g, which was higher than the data ever reported. The results showed that the adsorption capacity of activated alumina for Congo red was directly correlated to the specific surface area and the pore volume of activated alumina, and adsorption rate was correlated to the pore diameter of activated alumina. Meanwhile the adsorption process was better represented by the pseudo-second-order model kinetics and Langmuir isotherm.A lab-made boehmite with specific surface areas of 811.3m2/g was chosen to prepare alumina for the adsorption of fluoride at different calcining temperatures. The adsorption capacity of alumina adsorbent calcined at 600℃ was 360.78mg/g, which is higher than reported. The regeneration ability of Lab-F2 was better than the industrial adsorbent SD-F, and the adsorption capacities of Lab-F2-700 and Lab-F2-750 were over 71% of the adsorption capacities when they were used for the first time. The dissolution amount of aluminium ion during regeneration indicated that alumina adsorbents calcined at 700- 800℃ could be used as multi-regenerated adsorbents of fluoride in aqueous solution.