臭氧氧化对废水中RDX分光光度测试的影响因素

为研究臭氧(O_3)氧化后废水中环三亚甲基三硝胺(RDX)分光光度测试的干扰因素,进行了一系列的探索性实验。借助秩和检验和F检验,估计了分光光度法和高效液相色谱法(HPLC)测定的RDX数据间的系统误差。对比了分光光度法和HPLC得到的O_3氧化前后的废水及标准溶液中的RDX数据。用液相色谱-质谱联用(LC/MS)、气相色谱-质谱联用(GC/MS)检测了可能的干扰物质。分析引起RDX分光光度测试结果误判的原因。结果表明,在给定的显著性水平α=0.05下,两种方法测得的RDX数据间不存在系统误差。RDX废水中的有机物质经O_3氧化可产生甲醛,对分析结果产生干扰,但这部分甲醛可通过样品预处理进行有效去除。同时,O_3氧化不能将RDX彻底矿化,产生了低分子量的中间体,亚甲基二硝胺、二羟甲基硝胺以及6-硝基-2,4,6-三氮杂-3,5-二氧-己醛等。其中,亚甲基二硝胺和二羟甲基硝胺等胺类中间产物可与浓硫酸发生类似RDX的分解反应生成甲醛,成为干扰RDX分光光度测量的直接影响因素。

Factors Affecting the Spectrophotometric Determination of RDX in Wastewater by the Oxidation of Ozone

To investigate the interference factors affecting the spectrophotometric determination of cyclotrimethylene trinitramine (RDX) in wastewater following the oxidation of ozone (O3),a series of exploring experiments were carried out.With the help of the Rank sum test and F test,the system error between the RDX data determined by spectrophotometry and high performance liq uid chromatography (HPLC) was estimated.RDX data in wastewater and standard solution before and after oxidation of O3 obtained by spectrophotometry and HPLC were compared.The possible interfering substances were detected by liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS).The cause of misludging the spectrophotometric results of RDX was analysed.Results show that the systematic error does not exist between the RDX data determined by two test methods under the given significance level α =0.05.The organic substances in wastewater of RDX are oxidized by O3 to produce formaldehyde,which interferes with the analysis results,but this part of formaldehyde can be effectively removed by sample pretreatment.At the same time,RDX can not be completely mineralized during the oxidation of O3,producing low-molecular-weight intermediates,methylenedinitramine,dihydroxy-nitramine and 6-nitro-2,4,6-triaza-3,5-dioxo-hexanal and so on.Among them,the decomposition reaction of methylenedinitramine,dihydroxy-nitramine and other amine-intermediates can occur similar to RDX with concentrated sulfuric acid,formaldehyde formed by the reaction becomes the direct interferencing factors of interfering the determination of RDX by spectrophotometry.