Aluminum hydrolysis in mixed liquid reactors is a problem with multiple kinetic and mixing time scales. Since some of these times scales overlap, and since aluminum hydrolysis has multiple pathways (some of which are slowly reversed), we have modeled aluminum precipitation as a coupled mixing and chemistry problem. For the base neutralization of dilute aluminum chloride in a standard stirred reactor with Rushton impeller, mixing submodels are combined with simplified aluminum chemistry models to predict the effect of mixing on steady-state pH at various formation or neutralization ratios. Our simulations and experiments clearly show that mixing speed influences the shape of the pH titration curve, which suggests that the conversion of aluminum into amorphous and polymeric species is mixing-sensitive. The experimental and simulated results show less sensitivity to position of base injection in the reactor.
ASJC Scopus subject areas
- Environmental Chemistry