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 Alb and lower Ala values. The Al(III) chemical species calculated using Al-Ferron kinetics is more consistent with the experimental results.