Gamma spectrometry technique application to the 60Co sorption onto IRN-77 resin from radioactive wastewater: Equilibrium, Kinetic and Thermodynamic investigations

The performance of synthetic ion exchange resin IRN-77 have been studied in this work in order to use it as an adsorbent to remove radioactive isotope 60Co from nuclear wastewater by the sorption process, using the gamma spectrometry technique. The resin simple was identified using SEM and FTIR infrared spectrometry. The gamma radiation acquisition emitted from the fixed radioactive 60Co onto IRN-77 solid samples was carried out using the gamma spectrometry chain, equipped with an HPGe semi-conductor detector with high-resolution. Various factors were considered for the sorption process study such as 60Co concentration, contact time and temperature. The maximum adsorption capacity of the IRN-77 samples was determined by studying the adsorption isotherms; Kinetics models including thermodynamics were also studied and investigated. The experimental results showed that the adsorption reaction was adjustable to the pseudo-first-order and the Langmuir model was found to describe best the experimental results by obtaining a very important maximum adsorption quantity of 10.620 µCi of 60Co per 1 gram of IRN-77 adsorbent. A dimensionless separation factor RL was used to judge the favorable adsorption. The adsorption capacity of 60Co ions onto IRN-77 particles increased with the increasing of temperature. The values of the thermodynamic parameters have shown that the 60Co ions adsorption process was endothermic and favored at high temperatures with a positive value of the enthalpy ∆H° of 23,54 kJ/mol. The free energy’s values ∆G◦ are positive over the whole temperature range. The specific activities of the fixed 60Co radionuclide allow evaluating the solid samples IRN-77 resin's sorption capacity

Removal of methylene blue and basic yellow 28 dyes from aqueous solutions using sulphonated waste poly methyl methacrylate

9 Figuras, 8 TablasThis 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 SO3H appeared; another absorption band appeared in the region from 1138 to 1271 cm−1 that corresponds to the symmetric stretching of the SO2 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 mg g−1 and 222.22 mg g−1 for MB and BY28, respectively. The complete removal of MB and BY28 on the SW PMMA was achieved in less than 45 min. The Langmuir, Freundlich and Temkin models were applied and it was found that the equilibrium data could be satisfactory fitted to Langmuir adsorption isotherm. The kinetic study showed that the pseudo second order kinetic model correlates the experimental data. Furthermore, the thermodynamic parameters were determined for both dyes. As a result, the negative values of Gibbs free energy ∆G° indicated the spontaneity of the adsorption of MB and BY28 by SW PMMA. The negative values of ∆H° revealed the exothermic nature of the process and the negative values of ∆S° suggest the stability of MB and BY28 on the surface of SW PMMA.Peer reviewe

Recovery of synthetic copper ions by activated carbon from an industrial plastic PVC waste: Equilibrium, dynamic, kinetic and thermodynamic studies

18 figures, 16 tables.The recovery of Cu2+ ions by activated carbon obtained by an industrial polyvinyl chloride waste was examined. The raw material was treated chemically by KOH and activated carbon was obtained by pyrolysis at 700 °C. The textural surface properties of the adsorbent were characterized by XRD, SEM and FTIR. An adsorption experiments were conducted to assess the effect of pH, solid/liquid ratio, concentration and temperature on PVCW-AC removal effectiveness. Box-Behnken design was used to optimize the parameters. A removal percentage of 98 % and a maximum adsorption capacity of 145.63 mg/g were recorded. The adsorption followed pseudo-second order kinetic model.Peer reviewe

Modeling biosorption of Cr(VI) onto Ulva compressa L. from aqueous solutions

International audienceThe 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

Ni-exchanged cationic clays as novel heterogeneous catalysts for selectiveethylene oligomerization

International audienceMontmorillonite rich clays, including bentonite, acid washed clay (K10) and Al-pillared clay were exchangedwith nickel in order to prepare novel heterogeneous catalysts for the ethylene oligomerization. The catalyticproperties were examined in flow mode (p =3.0 MPa, T=150–350 °C), and the results were related to thetextural and acidic characteristics of the catalysts. Due to higher surface area and mesoporous volume, as well asmoderate acidity, Ni-exchanged K10 exhibited superior catalytic behaviour compared to others catalysts. Ni-K10was very active (TOF =570 h−1), stable (high conversion during 20 h on stream), and highly selective to linearC4 and C6 olefins