Efficient removal of Al(III) and P507 from high concentration MgCl2solution based on in-situ reaction strategy

For a highly efficient recycling of a wastewater containing a high concentration of MgCl2, Al(III) and P507 were scheduled to be removed in advance. In this study, the in-situ removal of Al(III) and P507 from a high concentration MgCl2solution at different pH values and Al/P molar ratios was investigated. The results showed that P507 formed organic complexes of Alx(OH)z+y-P507 at pH of 2.0−4.0. At pH of 4.0−5.0, Al(III) precipitated and transferred into Al(OH)3with a flocculent amorphous morphology. Active sites on the Al(OH)3surface enhanced the removal efficiency of P507. At pH of 6.0−6.5, Al(III) and Mg(II) formed layered crystalline Al(OH)3and MgAl2(OH)8with small pore channels and fewer active sites, resulting in a reduced removal efficiency of P507. When the Al/P molar ratio exceeded 13 and the pH was between 4.0 and 5.0, the removal rates of both Al(III) and P507 were higher than 98%, while the concentration loss of Mg(II) was only 0.2%−0.9%.