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The efficiency of styrene-divinylbenzene functionalized with trimethylamonium groups as sorbent for the direct dye removal from aqueous solutions was investigated.

The aim of this study was the colour fastness investigation of the new synthetized direct symmetrical azo-stilbene dye, using two of the film field domain reference tests, namely the wet-scrub and the UV tests. The dye was incorporated in a water-based resin, and then was applied on a PCV foil. The film colour parameters were determined before and after 200 wet-scrub cycles. Further, the dye was mixed with an acrylo-polyurethanic resin and then was applied on an aluminium plate, which was exposed to UV radiation for 414 h. The film colour parameters were recorded periodically. The maxima of the reflectance spectra depend on the UV time exposure. The quality of the film was analysed by the degree of gloss. A second focus was the elimination of the dye’s traces from wastewaters (these may be resulted from the industries which apply surface coating methods), using the active carbon powder. The main operational adsorption process parameters influence were investigated. Equilibrium, kinetic and thermodynamic studies were performed. The adsorption process was confirmed by the CIEL*a*b* colour space analysis. All colour studies were investigated using UV–Vis spectroscopy.

In the recent years, the adsorption capacities of synthetic polymeric adsorbents have been intensively studied due to their diversity in surface and porosity, physicochemical stability and the regeneration potentiality. In this study four synthetic polymers have been used as alternative adsorbent for the removal of two azo dyes from aqueous solutions. The effects of dye concentration, adsorbent nature, temperature, and pH of the solution onto the kinetics of the adsorption process were in detail investigated. With the increase in the initial concentration from 5.10–5 to 1.10–3 mol/L the amount of dye adsorbed increased, while the removal percentage decreased. The increase of the temperature (298–338 K) induced a positive effect on the adsorption indicating that the process is endothermic, and the increase of pH induced a decrease in removal percentage. The maximum dye removal percentage obtained was found to be up to 99 %. The experimental data were well correlated by the Sips adsorption model, and the results were applied for obtaining the equilibrium parameters.

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