Determination of the rate control step of chlorinated anilines in ligand exchange reactions on solid phase by using breakthrough technique
Küçük Resim Yok
Tarih
2003
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
ELSEVIER SCIENCE BV
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
Kinetic studies of chlorinated anilines as ligands on the cobalt(II)-carboxylated diaminoethyl-sporopollenin (CDAEsporopollenin) have been performed using continuous column runs. Adsorption rate measurements were carried out by using a UV-visible spectrophotometer, and rate control step of the reaction was determined. The adsorption of chlorinated anilines from solutions of different initial concentrations onto resin Was measured as a function of time at 25 degreesC. The initial ligand concentrations ranged from 6.0 x 10(-4) to 2.5 x 10(-3) mol l(-1). The results concerning the influence of the external solution concentration of the ligands upon the fractional attainment of equilibrium prove that the diffusion of the ligands into the resin beads plays an important role in the mechanism of the exchange reaction, although the exchange rate is chemical in its ultimate mechanism. A very fast initial adsorption resulting in an almost instantaneous attainment of the bulk of the equilibrium adsorption was followed immediately by a very slow rate of adsorption. In the case of 4- and 2,5-dichloroaniline, in all of the concentration range, the graphs of -ln[1 - U(alpha)] versus t were a straight line, which suggests that fractional attainment of equilibrium adsorption under film diffusion control is observed. On the contrary, 2- and 3-chloroaniline, the graphs were not a straight line and have underwent adsorption under particle diffusion control. (C) 2003 Elsevier Science B.V. All rights reserved.
Açıklama
Anahtar Kelimeler
adsorption kinetics, rate control step, breakthrough curve, sporopollenin, aromatic amines
Kaynak
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
WoS Q Değeri
Q2
Scopus Q Değeri
Q1
Cilt
219
Sayı
45352
