Coagulation Floculation De Quelques Composes Organiques Par Le Fer Ferrique En Milieu Aqueux

Author : Claudia Dumans Guedes
Publisher :
ISBN 13 :
Total Pages : 40 pages
Book Rating : 4.:/5 (494 download)

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Download or read book Coagulation-floculation des eaux issues des mines de fer : comparaison entre les coagulants minéraux et un coagulant organique issu de la moringa oléifera written by Claudia Dumans Guedes and published by . This book was released on 2004 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Quadrilátero Ferrífero area, Minas Gerais, Brazil, contains some of the largest global iron mineral deposits. There it is located Rio Doce Hydrographic Basin and the sub-Basin of Rio Piracicaba (Piracicaba River), a tributary of Rio Doce. The area around the high and medium course of Piracicaba River concentrates an important number of mining companies. Iron ore mining activities are considered one of the main agents responsible for raising chemical and mechanical soil leaching rates. In this work, the iron oxide content of the bottom sediment of the river was investigated in order to try to correlate the sediment accumulation and the mining activities of the region. The samples collected closest to the springs of Piracicaba river showed the higher contents of iron minerals, probably carried by the tributaries which drain the mining areas. At these stations, hematite concentration values are about four times higher than the average value for the river. Considering this, studying coagulation of iron oxide rich superficial waters from mining areas is imperative to those concerned with the environmental and hydrological equilibria of the river. We tried to do this by using two different coagulants, the traditional aluminum sulphate (alumen) and a natural biopolymer named Moringa oleífera. The superficial waters consist essentially of a suspension of goethite, hematite, kaolinite and quartz, which shows a positive net superficial charge under environmental pH conditions. Alumen showed a good performance in the destabilization of those iron oxide rich particle suspensions. Its coagulation/flocculation mechanism was investigated. Specific adsorption of hydrolysis products of aluminum salts on iron oxide particles followed by an heterocoagulation process involving differently charged substrates have been proposed to explain the turbidity reduction of the suspensions. However, since the seventies, aluminum is under suspicion of being responsible for neurovegetative diseases as Alzheimer, Parkinson's disturb and cancer. Moringa oleífera is a natural coagulant from a tree, well adapted to North and Northeastern Brazilian climate, whose seeds are largely employed in poor countries of Africa as an efficient coagulant for turbid waters. No test with Moringa in oxide rich waters has been reported so far. Its coagulation efficiency with iron oxide suspensions was similar to that of alumen. The mechanism of coagulation/flocculation of the aqueous extract of the seeds has been investigated through adsorption isotherms, infrared spectroscopy, X-Rays diffraction, Mössbauer spectroscopy, thermal gravimetric analysis, Zeta potential measurements and laser granulometric analysis. The active coagulant fraction of Moringa oleífera seeds are cationic proteins that adsorb on the oxide surface probably by a two step mechanism: establishment of a polypeptide monolayer followed by formation of multilayers that redisperse the destabilized particles.