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Modified chitosan gel beads, which had been prepared by the molybdate adsorption and coagulation (in the presence of molybdate) methods, were tested for As(III) and As(V) removal from dilute solutions (in the range 5-20 mg As L-1). The sorbent is very efficient at removing As(V) from acid solutions (optimum pH close to pH 2-3), whereas the sorption(More)
Metal ion biosorption has been well studied, but the nature of the interactions between metal ions and biomass is still controversial. This paper deals with a description of the influence of pH and sorbent on the removal of uranyl in solution. Infrared spectroscopy allows the influence of amino functions to be characterized for various fungal biomasses such(More)
A new process is described for the preparation of chitosan gel beads using molybdate as the gelling agent. This new gelation technique leads to a structure different from that produced during alkaline coagulation of a chitosan solution. Instead of a morphology characterized by large open pores, gel beads produced in a molybdate solution, under optimum(More)
Glutaraldehyde-cross-linked chitosan (GCC), thiourea derivative of chitosan (TGC) and rubeanic acid derivative of chitosan (RADC) have previously been shown to be very efficient at removing platinum and palladium from single component dilute acidic solutions. This study examines the competitive sorption of these metal anions in bi-component mixtures for(More)
Chitosan (a biopolymer) is an aminopolysaccharide that can be used for the treatment of colored solutions by coagulation-flocculation (as an alternative to more conventional processes such as sorption). Acid Blue 92 (a sulfonic dye) was selected as a model dye for verifying chitosan's ability to treat textile wastewater. A preliminary experiment(More)
Molybdate ion uptake both by raw chitosan and by glutaraldehyde cross-linked chitosan beads was investigated. This study focused on the identification of sorption mechanisms by means of several analytical procedures such as infra-red and reflectance spectrophotometries and CP-MAS 13C NMR analyses. Although the amine functions of glucosamine residues remain(More)
Prussian blue (PB) was immobilized in alginate capsules. The composite sorbent was used for the recovery of Tl(I) ions from slightly acidic solutions: optimum pH being close to 4. The sorption isotherm can be described by the bi-site Langmuir sorption isotherm. This means that the metal ion can be bound through two different sorption sites: one having a(More)
Ten chitosan preparations with different molecular weights (MW) and degrees of deacetylation (DD) were tested for coagulation of 5 g L(-1) bentonite suspensions at pH 5 and 7 in demineralized water (DW) and in tap water (TW). Coagulation was better in TW than in DW for every condition and lower doses of chitosan were required at pH 5 than at pH 7. More than(More)
In order to reduce the environmental impact due to land disposal of oil fly ash from power plants and to valorize this waste material, the removal of vanadium was investigated using leaching processes (acidic and alkaline treatments), followed by a second step of metal recovery from leachates involving either solvent extraction or selective precipitation.(More)
Polysaccharides display most of the properties needed for applications in catalysis, adsorption or remediation. Requisites common to these applications are appropriate surface functions to ensure substrate-material interactions, accessibility of the functional groups, and proper shaping for easy manipulation. Natural polysaccharides are well known as(More)