(140i) High Aspect Ratio CNTs As Sustainable Composites Adsorbents for the Removal of Ammonia from Industrial Wastewater.

Due to their remarkable properties CNTs have proven to be excellent sustainable composites in many applications. Their high surface area enables them to be sustainable adsorbents for different toxic pollutants in industrial waste. In this study high aspect ratio CNTs were synthesized in a special CVD reactor at optimized reaction conditions. The produced CNTs had aspect ratios ranging from 9000-12000 with a clear “flying carpet flakes” formation. The CNTs were further impregnated with metal oxides to further enhance their chemical and physical surface properties. The impregnation was confirmed with SEM, EDX and TGA characterization techniques. After impregnation the CNTs were tested in a batch mode for the removal of ammonia from wastewater. The effect of different experimental parameters on ammonia removal % and adsorption capacity was investigated. Increasing the pH of the solution above 9 did not have a significant effect on the removal %. Both diffusion and external mass transfer were enhanced by increasing agitation speeds leading to higher removal % for all metal oxides. This was also the case when varying temperature. Increasing the adsorbent dosage had a positive effect on the removal % due to the availability of more active sites for the removal. Among all metal oxides, aluminum had the best removal % at optimized conditions, while silver had the lowest. At optimized conditions experimental data was fitted using both, Langmuir and Frendlich isotherms. Both isotherms gave god fittings and the constants for each isotherm were calculated from the linearized form of the equations.