近年来水溶性聚磷酸铵（APP）作为螯合液体肥在农业上得到了广泛关注和应用。以两种不同聚合度分布的水溶性APP为原料,系统研究了Mg²⁺对两种水溶性APP的水解的影响。研究结果表明：在60 ℃反应110 h后,APP2溶液中Mg²⁺的质量分数为0、0.5%、1.0%、1.5%、2.0%时,其正磷酸铵的质量分数从未反应时的8.1%分别变为32.7%、31.3%、28.1%、30.7%、32.1%;APP8溶液中Mg²⁺的质量分数为0、0.5%、1.0%、2.0%、4.0%时,其正磷酸铵的质量分数从未反应时的13.3%分别变为53.3%、51.5%、51.6%、52.4%、46.9%。结合一级反应动力学模型,计算发现Mg²⁺对水溶性APP的水解具有减缓作用。不同聚合度分布的水溶性APP在相同Mg²⁺浓度下正磷酸铵含量的变化量有差异,针对作物需求,应该使用不同品质的水溶性APP。

Water-soluble ammonium polyphosphate（APP） as a chelated liquid fertilizer has received extensive attention and application in agriculture in recent years.The effect of magnesium ion on the hydrolysis of two water-soluble APPs was systematically studied by using water-soluble APP with two different polymerization degrees as raw materials.The results showed that the mass fraction of ammonium orthophosphate changed from 8.1% to 32.7%,31.3%,28.1%,30.7% and 32.1% when the mass fraction of Mg²⁺ in APP2 solution increased from 0 to 0.5%,1.0%,1.5% and 2.0% after 110 h at 60 ℃.When the mass fraction of Mg²⁺ in the APP8 solution increased from 0 to 0.5%,1.0%,2.0%,and 4.0%,the mass fraction of ammonium orthophosphate changed from 13.3% to 53.3%,51.5%,51.6%,52.4%,and 46.9%,respectively.Combined with the firstorder reaction kinetics model,it was found that Mg²⁺ had a slowing effect on the hydrolysis of water-soluble APP.The water-soluble APP with different polymerization degree distribution had different changes in the content of ammonium orthophosphate at the same Mg²⁺ concentration.For the crop demand,different quality water-soluble APP should be used.