Treatment technology of Cr, Se, and As in wastewater by layered double oxide containig capability for uptake, reduction, and acid neutralization

镁铝层状双氢氧化物通过将MgCl_2、FeCl_2和AlCl_3的混合溶液滴加到恒定pH的NaOH溶液中，制备了掺杂Fe ~（2+）的（Mg-Al LDH）。发现掺杂Fe ~（2+）的LDH能够通过Cr_2O_（72-）与插层Cl ~-的阴离子交换，生成Cr（OH）_3，Cr_2O_7 ~（2-）在生成的FeO（OH）表面的吸附。类似地，Fe 2+掺杂的LDH可以从水溶液中吸收As（V）和Se（VI）。这种LDH的优良性能是由Mg-Al LDH的阴离子交换性能和掺杂到Mg-Al LDH中的Fe 2+的还原活性引起的。这一过程可以被认为是通过Langmuir型吸附发生的，并且服从伪二级动力学。

Mg-Al layered double hydroxide (Mg-Al LDH) doped with Fe2+ was prepared by dropwise addition of a mixed solution of MgCl2, FeCl2, and AlCl3 to NaOH solution at a constant pH. The Fe2+-doped LDH was found to be able to remove Cr(VI) from an aqueous solution through the anion exchange of Cr2O72- with the intercalated Cl-, the production of Cr(OH)3, and the adsorption of Cr2O72- on the surface of the produced FeO(OH). Similarly, the Fe2+-doped LDH could take up As(V) and Se(VI) from an aqueous solution. The excellent performance of this LDH for the removal is caused by both the anion exchange properties of Mg-Al LDH and the reducing activity of the Fe2+ doped into the Mg-Al LDH. This process can be considered to occur through Langmuir-type adsorption, and to obey pseudo-second order kinetics.