Sulfur derivatives of chitosan for palladium sorption

Palladium is efficiently extracted from dilute acidic solutions using chitosan derivatives. Sorption performances are enhanced by modification of chitosan through the grafting of sulfur compounds (thiourea, rubeanic acid), which creates new chelating groups, on chitosan backbone using glutaraldehyde as a linker. A comparison of sorption isotherms and sorption kinetics of these two derivatives with those of glutaraldehyde cross-linked chitosan shows that the rubeanic acid derivative of chitosan is the more efficient for the uptake of palladium from dilute solutions. The chemical modification is suspected of bringing chelating functionalities to the ion exchange resin. Sorption capacity is not influenced by the particle size of rubeanic acid derivative of chitosan. Sorption isotherms are described by the Langmuir equation. Increasing the temperature of the solution has little effect on sorption performances. Sorption kinetics are not greatly influenced by the particle size of the sorbent. (C) 2002 Published by Elsevier Science B.V.