They are also responsible for a decrease of light penetration in waters and restraining of photosynthetic activity of plants. Furthermore, some colouring substances have been related to dysfunction of the kidney, reproductive system, liver, brain and central nervous system of living organisms. The studies have shown that among dyes there are highly toxic, carcinogenic and mutagenic ones. The latter seem to be particularly hazardous to the aqueous ecosystem. Dyes present in waters adsorb on the suspended organic matter forming sediments/sludges or due to their relatively high water-solubility remain dissolved. Although the most frequently reported level of dyes in effluents is in the range of 10 to 250 mg/L, it turns out that even very small quantities (less than 1 ppm for some dyes) might result in unwanted changes in the water physical and chemical characteristics. A significant problem is that concentration of dyes in waters located near an industrial plant can reach up to 7000 mg/L. About 10–15% of them are released to the environment during a manufacturing process. It is estimated that almost 100,000 various dyes are used in industry with over 700,000 tons annually production worldwide. Being applied they are subjected to chemical and physical processes, which might generate secondary products as burdensome for the environment as dyes themselves. Synthetic dyes are widely applied in the textile, pharmaceutical, food processing, leather tanning, cosmetics, plastics, photographic and paper industry. Brighter colours and better resistance of synthetic dyes to environmental factors resulted in almost complete displacement of natural dyes from their common usage. Therefore, the decolorization process of water resources is of great significance. The adsorption experiment, especially kinetic measurements, reveals the utility of mesoporous carbons in dye removing, taking into account not only the adsorption uptake but also the adsorption rate.ĭyes in waters, even at very low concentrations, are undesirable due to their hazardous effects on flora, fauna and human beings. The SAXS and TEM data confirm the regularity of mesoporous carbon structure. The results of these techniques are complementary, indicating the type of porosity and structural ordering, e.g., the pore sizes determined from the SAXS data are in good agreement with those obtained from nitrogen sorption data. The structural and acid-base properties of the investigated carbons were evaluated by Small-Angle X-ray Scattering (SAXS) technique, adsorption/desorption of nitrogen, potentiometric titration, and Transmission Electron Microscopy (TEM). In order to verify applicability of adsorbents for removing dyes the equilibrium and kinetic experimental data were measured and analyzed by applying various equations and models. The obtained carbonaceous materials and microporous activated carbon were investigated by applying different methods in order to determine their structural, surface and adsorption properties towards selected dyes from aqueous solutions. Mesoporous carbons with differentiated properties were synthesized by using the method of impregnation of mesoporous well-organized silicas.
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