On the mechanistic modeling of As(III) adsorption on gibbsite.
Arsenite adsorption on gibbsite was examined as a function of pH, ionic strength (I) and contact time (t(C)). As(III) showed a weak affinity for gibbsite surface. The trends of pH=f(Gamma(ads)) curves have showed a marked deviation from a typical anion adsorption edge showing a maximum Gamma(ads) around pH approximately 8.2. The experimentally derived proton exchange ratio has always converged to zero when 0.26< summation operator [As(III)]<7 microM and 6.2<pH<8.2. The isosteric heat of adsorption, DeltaH(r), exhibited invariant behavior with respect to Gamma(ads). The As(III) adsorption data was quantified by charge distribution multi-site complexation (CD MUSIC) model using the surface complex postulated below:
Weerasooriya
R
R
Institut für Geologie und Mineralogie, Lehrstuhl für Angewandte Geologie, Friedrich-Alexander Universität, Schlossgarten 5, Nürnberg Erlangen D-91054, Germany. rweerasooriya@hotmail.com
Tobschall
H J
HJ
Wijesekara
H K D K
HK
Arachchige
E K I A U K
EK
Pathirathne
K A S
KA
D000327:Adsorption; D001151:Arsenic / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D014873:Water Pollutants / Q000032:analysis
D014873:Water Pollutants; D001151:Arsenic