This contribution is a comparison study between synthetic hydroxyapatite (Sy-HAP) and commercial hydroxyapatite (C-HAP) for the removal of Pb2+ and Cd2+ ions present in wastewater from industrial effluents. The obtained results show that the equilibrium time required for complete adsorption of Pb2+ and Cd2+ ions on C-HAP and Sy-HAP is 15 min for both. The obtained removal efficiencies for Sy-HAP are 95.52% and 90.91% for Pb2+ and Cd2+ ions, respectively. Whereas, C-Hap presents lower removal efficiencies of 86.53% and 81.43% for Pb2+ and Cd2+ ions, respectively. Maximum adsorption was observed at pH 5; at lower pH levels adsorption was less. The experimental kinetic data fitted with the second order kinetic model. Thermodynamically, the adsorption process was endothermic and spontaneous in nature. Isotherm adsorption studies indicated that Langmuir, Freundlich and Temkin are the most valid models to describe and evaluate the adsorption process. The EDX results also confirmed the presence of lead and cadmium in adsorbents after adsorption. Finally, the HAP porous materials possess great potential for the removal of Pb2+ and Cd2+ ions from aqueous solutions and wastewater from industrial effluents.

No abstract

This study has investigated the solvent extraction of cadmium and lead ions from an aqueous solution in nitrate medium using aminooctyldiphosphonic acid (AODPA) as extractant in chloroform. In order to establish spectrophotometrically the concentration of metal ion in the aqueous phase before and after extraction, the Arsenazo III method was used. The effects of several extraction parameters on the extraction of these metals ions  including volume ratio between the aqueous and organic phases (1–5), extraction kinetic time (0–30 min), molar ratio Q (1–5), addition of HNO3 (pH =2–6), addition of KNO3 (0.01 – 1M), temperature (10–40°C) and the synergetic effect by adding TOPO (solvating agent) were evaluated. Thermodynamic parameters including the Gibbs free energy (ΔG0),enthalpy (ΔH0), and entropy (ΔS0) were calculated. Performed experiments showed that Pb (II) can be extracted till 73% when Cd (II) can be recovered completely after two cycles. The extraction of both metallic ions was spontaneous, endothermic and with a slight randomness.  Positive synergetic effect was observed at  a chelating agent/TOPO ratio of 3. It is a very encouraging result which can lead us to recover cadmium and lower the concentration of lead from wastewater.

Layered double hydroxides (LDHs) have been widely investigated in a wide range of applications in health, in the pharmaceutical industry and in the material of biotechnology industries. This material can be considered as a group of promising materials in the development of new health applications. The combination of phosphonic acid with LDHs material create a new hybrid material with new properties.In this work the synthesis of Zn/Al double lay-ered hydroxides by chemical co-precipitation method (molar ration 2) and grafted with Diamino Dodecyl Phosphonic Acid (DDPA) via anion-exchange mechanism. The samples were characterized and confirmed by X-ray diffraction (XRD), and the presence of diamino dodecyl phosphonic acid (DDPA ) was verified by Elemental analysis, BET analysis, and infrared spec-troscopy. Both of the samples were found to be showing antibacterial activ-ity. The zone diameters of Zn-Al- LDH were 40 mm and 25 mm for Esche-richia coli(ATCC 25922) and Streptococcus (ATCC 25922)and 20 mm for bacillus (ATCC 25922) whereas the same for hybrid LDH (Zn-Al-DDPA)were43 mm , 32 mm and 25 mm for the same bacteria showing stronger antibacterial activity of the grafted material over the material itself. The experimental results confirm the application of Zn-Al-DDPA in the field of antibacterial activities and may offer a promising antibacterial elucidation to the society.