Thermal decomposition of magnesium ammonium phosphate and adsorption properties of its pyrolysis products toward ammonia nitrogen

磷酸铵镁的热分解行为及热分解产物的氨氮吸附性能（英文）

High-purity magnesium ammonium phosphate （MAP） was precipitated by controlling pH value of the reaction system of 9.0-9.5. The thermal decomposition behavior of MAP and the adsorption properties of its pyrolysis products toward ammonia-nitrogen were also studied by XRD, SEM, TGA-DTA and FT-IR methods. The results indicated that high-purity MAP was obtained at pH value of 9.0-9.5. Upon heating to 100-120℃ for 120 min, MAP was thermally decomposed, losing water and ammonia concomitantly with a reduction in grain size and crystallinity. The capacity of pyrolysis products for ammonia nitrogen adsorption reached 72.5 mg/g, with a removal rate of up to 95% from an 800 mg/L solution. The characteristic diffraction peaks corresponding to MAP mainly appeared in their XRD patterns after adsorption of ammonia nitrogen. The pyrolysis products of MAP at 100-120 ℃ could be recycling-used as the chemical treatment regents of ammonia nitrogen in the practical application.

通过控制反应体系的pH值为9．0～9．5，制得高纯度的磷酸铵镁（MAP）；利用XRD、SEM、TGA-DTA及FT-IR等技术，研究MAP的热分解行为及热解产物对氨氮的吸附性能。结果表明，在pH值为9．0～9．5的条件下可制得高纯度的MAP。将MAP在100～120℃下热解120min，可将氨及水脱除，热解固体产物粒径变小，结晶度降低，对氨氮的吸附量达72．5mg／g，对起始浓度为800mg／L溶液的氨氮去除率达95％以上。吸附氨氮后，其XRD谱中主要出现MAP的特征衍射峰。循环使用结果表明，将MAP在100～120℃条件下发生热解，热解固体产物可循环用于氨氮的处理药剂。