Enhancing electrochemical preparation of polyaluminum chloride by a magnetic field

A novel effective method for preparing polyaluminum chloride (PAC) with high content of Al-13 polymer through conventional electrolysis coupled with rare earth Nd-Fe-B magnetic field was introduced. The content of Al-13 polymer in PAC synthesized by this method was highly influenced by the electrobath voltage (E), the magnetic flux density (B), the current density (i) and the distance between the two adjacent electrodes (d(adj)). A total aluminum concentration (Al-T) in the PAC solution of 0.8 mol l(-1) was obtained when the E. B and i was 2.2V, 0.4 T and 3.2 A dm(-2), respectively. The optimum d(adj) and circulating flow (Q(f)) were 20 mm and 23.71 h(-1). With accelerated mass transfer rate by external magnetic field and high Q(f), this process had the advantages of forming more AI(OH)(4)- as the precursor of Al-13 polymer and inhibiting the concentration polarization more obviously than conventional electrolysis process. Under the optimum conditions, the amount of Al-13 polymer in PAC accounted for 82.3% of the Al-T (Al-T=0.8 M, basicity=2.2), which was higher than that of PAC prepared by other methods. (C) 2008 Elsevier B.V. All rights reserved.