分光光度法测定环境空气中高浓度氨控制因素优化研究

Optimization of controlling factors on spectrophotometry for high concentration ammonia in ambient air

为提升化学法对环境空气中高浓度氨的检出浓度,采用正交实验对《环境空气氨的测定次氯酸钠-水杨酸分光光度法》(HJ 534—2009)中气体采集流量、采样体积、吸收液浓度等因素进行分析比较。结果得出,采样体积对空气中高浓度氨的测定影响显著。当采集流量为400mL/min、采样体积为5L、吸收液摩尔浓度为0.010mol/L时,对体积分数为0.05%的氨标准气体的回收率最高达96.69%。优化法氨测定的线性范围为0.10~379.46mg/m^3,比标准法测定上限浓度提升了约30倍。采用标准法、优化法和气相色谱法对重庆市长生桥填埋场场界内空气中的氨进行测定,发现标准法氨检出浓度偏低。优化法与气相色谱测试结果基本一致。优化法有助于空气中氨的吸收,适用于有氮源污染的场界内空气中氨的测定。

In order to improve the detection concentration of high concentrations of ammonia in the ambient air by chemical method,the impact factors on the determination of high concentration of ammonia in the“Ambient air-determination of ammonia-sodium hypochlorite-salicylic acid spectrophotometry”(HJ 534-2009)such as the gas collection flow,sample volume and the concentration of absorption liquid were studied by orthogonal test.The results showed that the sampling volume had a significant influence on analyzing ambient ammonia concentrations.When the sampling collection flow was 400 mL/min,the sample volume was 5 L and the concentration of absorbing liquid was 0.010 mol/L,the recovery rate of the standard ammonia,which volume fraction was 0.05%,was up to 96.69%,and the linear concentration range of the ammonia by the optimized method was 0.10-379.46 mg/m 3,which was about 30 times higher than the standard method.The concentrations of ammonia in the air of Changsheng Bridge landfill site in Chongqing had been measured by standard method,optimization method and gas chromatography method.The results showed that the concentration of ammonia measured by the standard method was low.Optimization method and gas chromatography test results were basically the same.Optimization method could be used to improve the absorption of the ammonia in the air and was suitable for the determination of ammonia in the air in the field with nitrogen source contamination.