粉煤灰中氨氮的测定方法研究

从浸提、干扰去除和显色3个方面对纳氏试剂分光光度法进行优化改进,建立了一种用于粉煤灰中氨氮测定的适宜方法,并利用浸提完全度和精密度实验对该方法了进行了评价。优化后的方法为:按固液比1∶10加入0.05 mol/L H_2SO_4振荡浸提30 min,再加入1.5 mL酒石酸钾钠溶液(500 g/L)和1.5 mL NaOH溶液(5 mol/L)去除金属离子干扰,最后加入1.5 mL纳氏试剂进行显色。粉煤灰浸提后残渣的蒸馏液中未检测出氨氮,说明浸提效果较为完全。同一样品的8次平行测定结果的相对标准偏差为6.10%,说明该方法稳定可靠。

Study on determination method for ammonia nitrogen in fly ash

The Nessler’s reagent spectrophotometry was optimized and improved from 3 aspects of extraction,interference elimination and color reaction,and a suitable method for determination of ammonia in fly ash was established. The method was evaluated by extraction completeness and precision experiments. The optimized method is as follows：adding 0.05 mol/L H₂SO₄ with solid-liquid ratio of 1∶10,extracting 30 min,then adding 1.5 mL potassium sodium tartrate solution （500 g/L） and 1.5 mL NaOH solution（5 mol/L） to eliminate the interference of metal ions,at last, adding 1.5 mL Nessler’s reagent for color reaction. The ammonia-nitrogen is not detected in the distillation liquid of the fly ash extraction residue,which indicates the completely leaching. The relative standard deviation of 8 parallel determinations results is 6.10%,indicating that the method is stable and reliable.