用于滤膜称重的饱和氯化镁溶液恒湿系统搭建与评估

发布时间：2018-04-11 16:14

本文选题：滤膜 + 称重箱　；参考：《环境科学》2017年08期

【摘要】：目前中国大气颗粒物污染严重,许多颗粒物测量工作使用基于滤膜采样的重量分析法,滤膜称重过程的质量保障至关重要.本文搭建了一套具有恒湿能力的滤膜平衡称重箱(1.2 m×0.6 m×0.8 m)并自制流量控制系统用于平衡和称量滤膜.通过测试空白滤膜和负载大气颗粒物的滤膜在不同相对湿度下的质量变化确定了30%~40%的平衡相对湿度并选用饱和氯化镁溶液控制称重箱内的相对湿度.用20 L·min~(-1)的干燥气通过装有饱和氯化镁溶液的恒湿箱,再将平衡后的气体通入平衡称重箱使其相对湿度达到稳定,随后用5 L·min~(-1)的流量维持.通过一个月的测试表明,系统在称重箱外相对湿度变化较大时,仍可维持称重箱内相对湿度在30.1%~34.0%之间.使用该恒湿系统称量60张滤膜,恒湿3次后称量的偏差均值不超过±0.02mg.相比于其他恒湿系统,这套系统具有简单、稳定、易于维护和成本低的特点.
[Abstract]:At present, atmospheric particulate matter pollution is serious in China. Many particulate matter measurement work uses gravimetric analysis based on filter membrane sampling, the quality assurance of filter membrane weighing process is very important.In this paper, a constant humidity filter membrane balance weighing tank (1.2 m 脳 0.6 m 脳 0.8 m) and a self-made flow control system are set up to balance and weigh the filter membrane.By measuring the mass change of the blank filter membrane and the filter membrane loaded with atmospheric particulates at different relative humidity, the equilibrium relative humidity of 30% and 40% of equilibrium relative humidity were determined and the relative humidity in the weighing box was controlled by saturated magnesium chloride solution.The dry gas of 20L / min ~ (-1) was passed through a constant humidity tank containing saturated magnesium chloride solution, then the equilibrium gas was put into the balance weighing box to make its relative humidity stable, and then the flow rate was maintained with the flow rate of 5 L / min ~ (-1).The results of one-month test show that the system can maintain the relative humidity of the weighing box between 30.1% and 34.0% when the relative humidity changes greatly outside the weighing box.Using the constant humidity system to weigh 60 filter membranes, the mean deviation of weighing after 3 times of constant humidity is less than 卤0.02 mg.Compared with other constant humidity systems, this system is simple, stable, easy to maintain and low cost.
【作者单位】：清华大学环境学院;
【基金】：国家重点基础研究发展规划项目(2013CB228505) 国家重点研发计划项目(2016YFC0200102)
【分类号】：X513

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