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The presence of dyes is one of the main contributors to the organic load in textile effluents. In this study a mixture of surfactants, produced from animal/vegetable fats, was used to remove the Direct Yellow 27 dye from a synthetic wastewater through an ionic flocculation process. It was evaluated the effect of contact time, temperature, and surfactant concentration on dye removal efficiency. It was also evaluated the kinetics, equilibrium, and diffusion mechanism of the process. The kinetics of the process was well described by both Pseudo‐second order and Elovich models. The transport of dye molecules to the surfactant flocs is controlled by the external layer. Equilibrium data showed a good fit to the Langmuir model. A removal rate of 93% was achieved in a single stage, after 5 h of contact time.

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A comparative evaluation is presented of physical and chemical treatments performed on coconut shell powder, in relation to the adsorption capacity of Cu 2+ /Cd 2+ ions. The chemical treatment consisted of impregnation with monoethanolamine (mass ratio of 1:1) or a microemulsion (composed of 10 wt % sodium octanoate). The physical treatment was through steam explosion (P = 5 bar, T = 210 °C). Treatment efficiency was assessed using physical characterization of the adsorber material. Assessment of the ion adsorption capacity was performed in batch mode. The comparative investigation was carried out based on the Langmuir model constants, kinetic constants, and thermodynamic parameters. The efficiency of the modifications was also evaluated through adsorptiondesorption cycles.

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