2 research outputs found
Characterization of Phosphate Adsorption on Sediments
No full textAbstractPhosphate sorption by sediments sampled downstream of the Béni Haroun water dam was studied. Experiments were conducted to assess the effects of time, phosphate concentration, sediment dose, pH and temperature. Infrared spectroscopic analyses and sequential extractions were performed to characterize the mechanism of phosphate interaction with the sediments. The results of the macroscopic tests indicated that the fixing of phosphate ions is accomplished in two stages: the first rapid and the second slow. The kinetic data corresponded very well to a pseudo second-order equation. The equilibrium data was described by a Freundlich isotherm. The adsorption capacity increased with increasing temperature. It was highest in the pH range 7-8. In the IR spectrum, the adsorbed phosphate was characterized by a peak at approximately 1145cm-1 indicating relatively strong bonding between the adsorbed phosphate and the sorptive sites on the surface. In the sediments, phosphorus is mainly bound to calcium
Photocatalytic degradation of antiepileptic drug carbamazepine with bismuth oxychlorides (BiOCl and BiOCl/AgCl composite) in water: Efficiency evaluation and elucidation degradation pathways
No full textInternational audienceThe heterogeneous photocatalytic degradation of carbamazepine (CBZ) was investigated in the presence of BiOCl/AgCl composite photocatalyst under simulated sunlight irradiation in water. BiOCl/AgCl composite showed higher photocatalytic activity than pure BiOCl for CBZ degradation. The photocatalytic mechanism analysis was based on byproducts identification by LC-MS-QT of and active species trapping or inhibiting experiments. The results revealed that the first step of the transformation mainly results in an electron transfer implying positive holes and to a lesser extent in hydroxyl radical's involvement. The enhanced photocatalytic performance of BiOCl/AgCl was proved to be related to the suitable conduction and valence band interaction that extends optical response range but also improves the efficient separation of photoinduced electron-hole pairs. BiOCl/AgCl composite totally removed CBZ from natural surface water after 30 min irradiation, suggesting its potential application to wastewater treatments. Eight intermediate products were identified demonstrating that CBZ transformation occurs through two main routes from CBZ radical cation, hydroxylation of ring (aromatic or seven membered rings), followed by further oxidation, rearrangement ring and hydroxylation. (C) 2016 Elsevier B.V. All rights reserved
