Al-Ferron kinetics and quantitative calculation of Al(III) species in polyaluminum chloride coagulants

The effect of prehydrolysis and the presence of silicate and/or sulfate on polyaluminum coagulants were investigated. A new Al-Ferron kinetics method was developed to monitor and calculate Al speciation. The results showed that the Al-Ferron kinetics fit a binary pseudo first order rate equation. Sulfate and silicate had different influences on Al-Ferron kinetics. Al-Ferron complexation timed spectrophotometry is the commonly used method of determining Al speciation but this new Al-Ferron kinetics calculation method shows different species distributions. For all the coagulants except polyaluminum silicate chloride (PASiC), the new method yielded higher Al-b and lower Al-a values. The Al(HI) chemical species calculated using Al-Ferron kinetics is more consistent with the experimental results. (c) 2005 Elsevier B.V. All rights reserved.