Abstract

The percentage composition of Al₁₃, [AlO₄Al₁₂(OH)₂₄(H₂O)₁₂]⁷⁺, in water treatment coagulants is an important criterion in the development and use of polymeric coagulants. Polymeric coagulants are generally used in cold climates or with highly turbid waters. Size exclusion chromatography–flame atomic absorption spectrometry (SEC-FAAS) can separate Al₁₃ and monomeric Al within 6 min. The percentage composition of Al₁₃ and monomeric Al is determined by solving two simultaneous equations. Due to overlapping peaks, a 10% error is associated with this method of quantification. This method can be used on coagulants of varying “r values” (r = [OH⁻]/[Al³⁺]), or on mixtures of those coagulants and monomeric aluminium.