Natural geochemical processes and anthropogenic activities produce selenium (Se)-containing wastewater, in which selenium is present as selenous acid (Se(IV)) and selenic acid (Se(VI)). Herein, we evaluated the Se removal performances of magnesium oxide (MgO) with different crystallinities at pH 10.5. Normal MgO and low-crystalline (LC-MgO) were reacted in 1, 2, and 5 mg dm⁻³ Se(IV) or Se(VI) solution for 120 min. The Se concentrations of both the species did not apparently decrease in the normal MgO systems. However, >90% of Se(IV) was successfully removed by LC-MgO within 5 min under all conditions. X-ray diffraction (XRD) analysis indicated that Se(IV) was removed via surface complexation on Mg(OH)₂ formed by the rapid hydration of LC-MgO. The enhancement of Se removability of the LC-MgO system was explained by the rapid hydration of the higher surface area of LC-MgO when compared with that of normal MgO. Majority of the Se(VI) (60–80%) was removed by LC-MgO during the first 20 min; however, it was gradually released back into the solution over time. During hydration, the changing XRD peak patterns and zeta potential of LC-MgO indicated that the increased charge density obtained by the accumulation of Mg²⁺ released via MgO dissolution would cause the temporal uptake of Se(VI) in the interlayer of Mg(OH)₂. Subsequently, the charge density decreased with the hydration of Mg²⁺, indicating that Se(VI) was redissolved. Therefore, LC-MgO is a promising material for treating Se-containing alkaline wastewater. However, short-time operation and low concentration (<1 mg dm⁻³) must be ensured for successful Se(VI) removal.

自然的地球化学过程和人为活动会产生含硒的废水，其中硒以亚硒酸（Se（IV））和硒酸（Se（VI））的形式存在。在本文中，我们评估了在pH 10.5下具有不同结晶度的氧化镁（MgO）的Se去除性能。普通MgO和低结晶度（LC-MgO）在1、2和5 mg dm ^-3 Se（IV）或Se（VI）溶液中反应120分钟。在正常的MgO系统中，两种物质的Se浓度均未明显降低。但是，在所有条件下，LC-MgO均在5分钟内成功去除了90％以上的Se（IV）。X射线衍射（XRD）分析表明，Se（IV）通过在Mg（OH）₂上的表面络合而去除通过LC-MgO的快速水合形成。与常规MgO相比，LC-MgO较高表面积的快速水合可以解释LC-MgO系统的Se去除性增强。在最初的20分钟内，LC-MgO去除了大部分Se（VI）（60-80％）；但是，随着时间的推移，它逐渐释放回了解决方案中。在水合过程中，LC-MgO的XRD峰模式和zeta电位变化表明，通过MgO溶解释放的Mg ²⁺的积累而获得的增加的电荷密度将导致Se（VI）在Mg（OH）的中间层中的时间吸收）₂。随后，电荷密度随着Mg ²⁺的水化而降低，表明Se（VI）已重新溶解。因此，LC-MgO是用于处理含硒碱性废水的有前途的材料。但是，必须确保短时运行和低浓度（<1 mg dm ^-3）才能成功去除Se（VI）。