Removal of cadmium and mercury ions from aqueous solution by sorption on treated Pinus pinaster bark: kinetics and isotherms.
Formaldehyde pretreated Pinus pinaster bark was used to sorb Cd2+ and Hg2+ from aqueous solutions. The sorption kinetics showed hyperbolic dependence of the proportion of cation adsorbed on time, and the sorption isotherms were satisfactorily fitted by Freundlich equations, with k and n values showing Hg2+ to be more efficiently sorbed than Cd2+. Except for low cation concentrations, for which sorption was practically total at all initial pH > or = 6, sorption increased in this range, in keeping with a mechanism based on ion exchange with the hydroxyl protons of ring B of the procyanidin units of the tannins in the bark.
Vázquez
G
G
Department of Chemical Engineering, Faculty of Chemistry, University of Santiago de Compostela, Spain.
González-Alvarez
J
J
Freire
S
S
López-Lorenzo
M
M
Antorrena
G
G
D000042:Absorption; D000327:Adsorption; D001709:Biotechnology / Q000379:methods; D002104:Cadmium / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007700:Kinetics; D008628:Mercury / Q000737:chemistry*; D008956:Models, Chemical; D028223:Pinus; D024301:Plant Bark / Q000378:metabolism; D011522:Protons; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000378:metabolism
D007477:Ions; D011522:Protons; D002104:Cadmium; D014867:Water; D008628:Mercury