Y. Salingar et al., KINETICS OF ION REMOVAL FROM AN IRON-RICH INDUSTRIAL COPRODUCT .1. CHLORIDE, Journal of environmental quality, 23(6), 1994, pp. 1194-1200
An industrial TiO2 extraction process results in a Fe-rich material (I
RM) that contains substantial chlorides. Recent investigations showed
that washed IRM may serve as a soil amendment for agricultural use. Ye
t, washing processes at the industrial production facility are current
ly problematic and costly, and it is essential to devise effective pro
cedures for CI removal. This study was conducted to determine the mech
anism of CI retention, and to ascertain whether the rate of Cl removal
was governed by time-dependent surface-chemical kinetics or diffusion
(transport)-controlled kinetics. The IRM samples we used throughout t
he study were homogenous. It was physicochemically characterized and c
oncentrations of heavy metals were determined. The IRM batch studies r
evealed negative CI adsorption, even though its point of zero charge w
as 8.3. Column studies showed that 92% of the CI was removed with the
first pore volume. Additionally, the salt removal decreased the electr
olyte concentration, caused dispersion, and, ultimately, lowered the h
ydraulic conductivity. Stirred-how kinetic studies established that Cl
leaching was a function only of the total volume that flowed through
the chamber, and that no chemical kinetics were involved.