Formation of Al30 from aqueous polyaluminum chloride under high temperature: Role of Al13 aggregates

• Al30 production in PAC with aging is found higher than that in PAC without aging.
• Al monomer could suppress the formation of Al14 in the process of Al30 formation.
• PAC with basicities of 2.0–2.4, facilitates the Al30 formation from Al13.

Al30 is a new kind of polymeric aluminum species with 30 aluminum atoms and believed to be one of the optimum coagulation species just as Al13. However, the preparation of Al30 species had been energy and time consuming. Besides its formation mechanism have not been well understood. In this study, the influence of Al13 aggregates and monomeric Al under high temperature circumstance on Al30 formation was studied by 27Al NMR and dynamic light scattering (DLS). The results showed that the particle sizes of Al13 aggregates tend to increase in aging process without significant change of their Al13 content. The Al13 aggregates induced by aging promotes higher yield and faster production of Al30, while the Al13 aggregates prepared by basicity increase would hamper the Al30 formation. These results should be very helpful to improve the preparation of the promising Al30 species.

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