This work focuses on two different environmental problems: the recovery of plastic wastes PMMA (W PMMA) and their application in the removal of textile dyes Methylene Blue (MB) and Basic Yellow 28 (BY28) in aqueous solutions. The selected waste plastic was upgraded to produce an adsorbent suitable for dyes removal. For that, the material was grinded cryogenically up to a particle size of less than 100 μm and treated with sulfuric acid. The sulphonated waste PMMA (SW PMMA) was characterized by FTIR, scanning electronic microscopy (SEM) and chemical composition analysis (C, H, N, O and S content). The formation of sulphonic groups in the material after sulphonation reaction has been successfully demonstrated by FTIR, and can be observed mainly in the region 3087 cm -1 to 3657 cm -1 , where an intense band bound to the stretching of the SO 3 H appeared; another absorption band appeared in the region from 1080 cm -1 to 1271 cm -1 that corresponds to the symmetric stretching of the SO 2 group. The effects of solution pH, initial dyes concentration, adsorbent dose and temperature were studied in batch experiments. The obtained data showed that SW PMMA adsorbent exhibit significant adsorption capacities of 97.09 and 222.
The marine biomass Ulva compressa L. (ECL) was used as a low-cost biosorbent for the removal of Cr(VI) from contaminated aqueous solutions. The operating variables were optimized: pH ∼ 2, initial concentration of 25 mg/L, solid/liquid ratio of 6 g/L and a temperature of 50 °C, leading to an uptake elimination of 96%. A full factorial experimental design technique enabled us to obtain a mathematical model describing the Cr(VI) biosorption and to study the main effects and interactions among operational parameters. The equilibrium isotherm was analyzed by the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models; it has been found that the adsorption process follows well the Langmuir model. Kinetic studies showed that the pseudo-second order model describes suitably the experimental data. The thermodynamic parameters indicated an endothermic heat and a spontaneity of the Cr(VI) biosorption onto ECL.
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