Studium možností využití uhlíkatých produktů spalování paliv pro záchyt polutantů z vodného prostředí

Abstract

This thesis investigates the possibility of utilization of carbonaceous products from fuel combustion for the retention of pollutants from aqueous environment. The study deals with the retention of Naphthol Green B from wastewater using unburned carbon; particular attention has been paid to characterization of the unburned carbon as an adsorbent, to description of the adsorption process of Naphthol Green B and the adsorption mechanism. Moreover, the attention has been drawn to factors affecting the adsorption process, for example, the effect of contact time, initial concentration, pH, surfactants etc. Finally, the adsorption of Naphthol Green B on unburned carbon has been compared with other carbonaceous materials and the adsorption experiments have been performed in real waste water as well. Adsorption properties of unburned carbons have been assessed by various analytical methods indicating meso- and macroporous character of the material with a relatively high specific surface area suggesting the suitability of unburned carbon for adsorption of dyes and other large-molecule- pollutants from aqueous environment. The best description of the adsorption kinetics has been obtained by a two-site pseudo-second order kinetics showing that the uptake of dye occurs on energetically heterogeneous surface of unburned carbon. Multilinear character of diffusion model has revealed that the pore-diffusion plays an important role in a rate-limiting step of the adsorption kinetics. The adsorption process has been described by Temkin model. Initial concentration, pH of the solution and the presence of surfactants represent a major opportunity how to influence the adsorption process. With increasing concentration of the dye in the solution and with decreasing pH, the adsorbed amount of Naphthol Green B increases. The adsorbed amount has increased considerably in the presence of small amounts of (cationic) surfactants. The possibility of utilization of the unburned carbon for the retention of pollutants from real wastewater seems to be feasible. The presence of the unburned carbon has resulted in the decrease of Naphthol Green B concentrations; nevertheless, other parameters (e.g. the concentrations of other ions) have been affected as well. For this reason, further research with particular attention paid to all significant waste water parameters is advised. The comparison of the five studied adsorbents (two unburned carbons, parrent lignite and two cokes) has revealed that the adsorption of Naphthol Green B has been the most effective in case of the unburned carbons.