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In this contribution, we report the investigation on removing of the oxochromium (VI), a hazardous species, using HCl-doped polyaniline (PAni-HCl) as adsorbent versus particles size. PAni-HCl has been successfully elaborated by conventional oxidative chemical method in the temperature range (0–3 °C). The recovered powder was milled and sieved into size ranges of < 50, 50–63, 125–160 and > 200 µm. The batch adsorption experiments were performed at 25 °C, using 250 mg of PAni-HCl dispersed in 250 mL of Cr(VI) aqueous solution (250 mg L−1). The Cr(VI) uptake was significantly influenced by both the particle size and contact time. Smaller particle sizes allow a quick initial adsorption and high removal efficiency (~100%). The kinetics of the Cr(VI) adsorption follow the pseudo-second-order model. A good correlation was demonstrated between the removal chromium (VI) properties (Qe,exp, k2 and τ(%)) and the (normalized) mean diameter ratio. [ABSTRACT FROM AUTHOR]

In this study, we report elaboration of a thin film of CoOx on a low carbon unalloyed steel substrate by electrochemical route and the study of its electrocatalytic performances with respect to the evolution reaction of oxygen (OER) in NaOH medium. The elaborated deposits were well-characterized using X-ray diffraction. Kinetic and thermodynamic parameters such as exchange current density, Tafel slope, reaction order with respect to OH– ions and apparent activation energy were studied. The CoOx displays satisfactory OER performance in an alkaline medium, with a low overvoltage of 362 mV at 10 mA/cm2 and a Tafel slope of 81 mV/dec at 293 K. The apparent kinetic activation energy (= 29.79 kJ/mol) was similar to those obtained for the reported catalytic electrode materials. The O2 gas obtained on the cobalt oxide electrode was 2.865 mmol/s.cm2, which is 28 times higher than that obtained for the platinum electrode (0.102 mmol/s.cm2). Chronoamperometry demonstrates a better electrochemical stability under a polarization potential of 2 V in 1 M NaOH for nearly 25 h. The low cost, the high OER performance, as well as the good stability of the CoOx electrode make it a promising candidate for the industrial-scale water electrolysis. [ABSTRACT FROM AUTHOR]

The purpose of this research is to evaluate the adsorption kinetics, isotherms and thermodynamic parameters correlating the removal of 60Co2+ radioactive ions from waste water of the primary cooling circuit of the Nuclear Uranium Reactor (Nur / Draria-Algeirs) on Fe(III)-modified Algerian bentonite. Characterization was done using X-ray diffraction, SEM analysis, X-ray Photoelectron Spectroscopy and BET method. The pseudo-second-order kinetic model provided the best fit to experimental data. The two-parameter adsorption model of Langmuir and both of the three-parameter models Langmuir–Freundlich and Toth are the most appropriate for fitting experimental results. The adsorption process was found to be endothermic in nature. [ABSTRACT FROM AUTHOR]

We report the synthesis and characterization of a new mesoporous cobalt oxide-infiltrated NaY zeolite prepared by ion-exchange route. The scanning electronic microscopy (SEM) image shows homogenous and uniform grains size distributions smaller than 1 μm, unlike to CoO particles, elaborated under the same conditions. The energy dispersion spectroscopy (EDS) data confirm the presence of cobalt, oxygen, silicon, and aluminum. The X-ray diffraction indicates a partial crystallization of cobalt oxide and the formation of new phases. N adsorption-desorption measurement shows a high-specific surface area for the modified material (579 m g), with Barrett-Joyner-Halenda (BJH) pore diameters in the range (3-8 nm). The cyclic voltammetry indicates a typical faradic process, and the electrochemical impedance spectroscopy exhibits Warburg diffusion at low frequencies. The charge-discharge curve shows a clear improvement in the charge capacity of the modified material compared to CoO, due to the increased specific surface area. The galvanostatic charge-discharge tests of the modified electrode exhibit a typical battery behavior preceded by a pseudo-capacitive phenomenon. [ABSTRACT FROM AUTHOR]