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The objective of this work is to determine the kinetic and thermodynamic properties of adsorption of Pb(II) from aqueous solutions by synthetically prepared MgFeAl-CO 3 as layered double hydroxide (LDH) adsorbent. Compared to other adsorbents for heavy metal removal from aqueous solutions, LDH materials possessed many advantages such as nontoxic synthesis, chemical stability, environmentally friendly, and facile separation from the water solution. The synthesis of LDH was achieved by a co-precipitation method. The reaction products were characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive spectroscopy and N 2 sorption-desorption isotherm analysis. The adsorption rates were investigated. The effect of the parameters such as contact time, initial metal ion concentration, and temperature on the adsorption of the Pb(II) was studied. Equilibrium was achieved in 60 min and the equilibrium adsorption capacity was found to be increased with the increase in the Pb(II) initial concentration. The removal efficiency of Pb(II) increases from 59.50% to 71.15% when the temperature increases from 15°C to 60°C. The pseudo-first-order, pseudo-second-order, and Elovich kinetic models were tested and the first was found to fit better to the experimental data. The application of the intra-particle diffusion model demonstrates that the surface diffusion and the intra-particle diffusion occur in parallel during the adsorption of Pb(II) onto MgFeAl-CO 3 . The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Redlich-Peterson, and Temkin isotherm models. The results indicated that the Redlich-Peterson and Langmuir isotherms were the most suitable models for the obtained experimental data and the Langmuir maximum adsorption capacity of the MgFeAl-CO 3 is found to be 117.86 mg g -1 at 298.15 K. The thermodynamic analysis of the adsorption of Pb(II) on MgFeAl-CO 3 reveals that the present adsorption process is a spontaneous and endothermic reaction.

The aim of this work was to develop new low-cost adsorbents obtained from animal origins, available in large quantities and environmentally friendly. Raw shrimp shell (RSS), a biomaterial of animal origin, is abundant, available, renewable and non-toxic. It has physicochemical properties that can induce a significant adsorptive activity. In this study, the removal of phosphate anions (H2PO4-, HPO42-) from aqueous solution by adsorption onto raw shrimp shells was studied. The surface micro-morphology of the biomaterial was investigated using scanning electron microscope and qualitative element composition was analyzed using energy dispersive X-ray and infrared spectroscopies. The efficiency of the biomaterial was investigated using a batch adsorption technique under different experiment conditions, achieved by varying parameters such as adsorbent dosage, the contact time, the initial phosphate anion concentrations, the temperature and the initial solution pH. Results show that the kinetics adsorption of phosphate ions by the biomaterial is relatively quick and the biomaterial showed a high adsorption capacity of 0.20 g∙g-1 and 0.4 g∙g-1 for HPO42- and H2PO4-, respectively. The adsorption data were analyzed using the Langmuir, Freundlich and Temkin adsorption isotherms to determine the nature of the adsorption sites. Both Langmuir and Freundlich adsorption models showed good fits to the experimental adsorption data.Cette étude s’inscrit dans le cadre de certains de nos travaux visant la valorisation de matériaux naturels d’origine végétale, animale et minérale pouvant rendre les procédés d’épuration des eaux simples et moins coûteux. Les carapaces de crevettes à l’état brut, biomatériau d’origine animale, entrent dans cette catégorie. Il est abondant, disponible, renouvelable et non toxique, et présente des propriétés physicochimiques qui peuvent induire une activité adsorbante importante. Le biomatériau a été caractérisé par microscopie électronique à balayage, par spectroscopie d’émission X et spectroscopie infrarouge. Une étude complète de l’adsorption des ions phosphates (HPO42- et H2PO4-) sur des carapace de crevettes à l’état brut a été effectuée. L’influence de paramètres physicochimiques tels que la masse d’adsorbant, le temps de contact, le pH, la température et la concentration initiale de phosphate a été étudiée. Les résultats obtenus montrent une cinétique rapide et une grande capacité de ce biomatériau à retenir les ions phosphates pouvant atteindre 0,20 g∙g-1 pour HPO42- et 0,40 g∙g-1 pour H2PO4-. Les isothermes d’adsorption étudiés (Langmuir, Freundlich et Temkin) montrent une bonne corrélation avec les modèles de Langmuir et de Freundlich

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Today, organic wastes (paints, pigments, etc.) are considered to be a major concern for the pollution of aqueous environments. Therefore, it is essential to find new methods to solve this problem. This research was conducted to study the use of electrochemical processes to remove organic pollutants (e.g., crystal violet (CV)) from aqueous solutions. The galvanostatic electrolysis of CV by the use of Ti/Pt/SnO2 anode, were conducted in an electrochemical cell with 100 mL of solution using Na2SO4 and NaCl as supporting electrolyte, the effect of the important electrochemical parameters: current density (20–60 mA cm−2), CV concentration (10–50 mg L−1), sodium chloride concentration (0.01–0.1 g L−1) and initial pH (2 to 10) on the efficiency of the electrochemical process was evaluated and optimized. The electrochemical treatment process of CV was monitored by the UV-visible spectrometry and the chemical oxygen demand (COD). After only 120 min, in a 0.01mol L−1 NaCl solution with a current density of 50 mA cm−2 and a pH value of 7 containing 10 mg L−1 CV, the CV removal efficiency can reach 100%, the COD removal efficiency is up to 80%. The process can therefore be considered as a suitable process for removing CV from coloured wastewater in the textile industries.