新型水泥基材料富镁C3A对氮磷的共去除

将镁掺杂进水泥基材料铝酸三钙（C₃A）制得新型富镁铝酸三钙（Mg@C₃A）应用于水体氨氮（NH₄⁺-N）和磷（PO₄^3-）的共去除.通过批量实验，考察了Mg@C₃A投加量、氮磷浓度、溶液pH值、温度等因素对NH₄⁺-N、PO₄^3-共去除的影响，并阐述了共去除机制.结果表明：Mg@C₃A是由Mg掺杂C₃A同构体和表面MgO组成，其中Mg的引入未改变C₃A晶体结构和基本形貌.Mg@C₃A材料对NH₄⁺和PO₄^3-具有良好的共去除效果.当Mg@C₃A的投加量为3g/L，NH₄⁺和PO₄^3-的最大去除量分别为38.4，78.9mg/g；温度升高有利于Mg@C₃A对NH₄⁺和PO₄^3-的共去除，而高pH值可促进NH₄⁺的去除.Mg@C₃A材料对NH₄⁺的去除主要是OH^-的中和作用和鸟粪石的沉淀作用主导，PO₄^3-主要是与Mg²⁺或Al³⁺结合形成鸟粪石或磷酸铝被去除.

The co-removal of ammonium and phosphate by novel cement-based material magnesium-rich tricalcium aluminate and its mechanism investigation

Magnesium-rich C₃A (Mg@C₃A) was successfully prepared via doping magnesium into cement-based material tricalcium aluminate (C₃A) for the co-removal of ammonium (NH₄⁺-N) and phosphorus (PO₄^3-). The effects of Mg@C₃A dosage, contaminants concentration, solution pH value, and temperature as well as the mechanism were investigated. Mg@C₃A was composed of the C₃A isomorphism formed by the replacement of Ca with Mg and the surface MgO, in which the Mg doping does not affect the cubic symmetric structure and morphology of C₃A. The maximum removal capacity of NH₄⁺ and PO₄^3- were 38.4, 78.9mg/g at the Mg@C₃A dosage of 3g/L, respectively. The increase of temperature was conducive to the co-removal of NH₄⁺ and PO₄^3-by Mg@C₃A. High pH value enhanced the NH₄⁺ removal. The removal mechanism of NH₄⁺ was mainly neutralization and the precipitation; PO₄^3- was removed via the precipitation combining with Mg²⁺ or Al³⁺ to form struvite or aluminum phosphate.