纳氏试剂比色法在微量氨测定中存在的问题及改进建议.pdf

监 测 与 评 价 纳氏试剂比色法在微量氨测定中存在的问题 及改进建议 张素荣 潘巍慧 通州市环境监测站, 江苏 226300 摘要 研究了纳氏试剂比色法在微量氨的测定中存在的问题, 提出了通过减少吸收液体积、增加采样体积的途径合理 地降低方法检出限, 从而解决了在低浓度氨测定中检出限过高的矛盾。 关键词 纳氏试剂比色法 微量氨 问题 改进建议 1 引言 以纳氏试剂比色法测定空气中氨具有简便、快 速、 准确等优点 ,长期以来 ,在大气和室内空气的环境 监测中得到了广泛的应用。按国家标准方法 GB T1466893 规定 ,吸收液体积为 50 mL、采样体积为 10 L 时 ,该方法的最低检出浓度为 0. 25 mg m 3 , 然而 室内空气质量标准 GB T188832002 与工业企 业设计卫生标准 TJ3639 中都规定氨的室内空气 质量标准值及居住区大气中的最高容许浓度均为 0. 20 mg m 3 小时均值 。相对于该标准 , 国家标准方 法规定的检出限明显偏高, 已经没有实际应用价值, 尤其在微量氨的监测中。针对这一具体问题 ,本研究 从改变吸收液体积和采样体积入手 ,就纳氏试剂比色 法测定空气中氨的检出限进行了重新测定和设计 ,以 适应空气质量标准。 2 减少吸收液体积 国标方法 GB T1466893 中要求, 样品采集中 需用 50 mL 或125 mL 大型玻板吸收瓶或大型冲击式 气泡吸收瓶进行采样, 吸收液 0. 005 mol L H2SO4 的 体积为50 mL。 选择 50mL 大 型玻板吸收瓶和 10 mL 大型冲击 式吸收瓶 , 分别装入 50 mL 和 10 mL 吸收液 , 以 0. 5 L min流量, 采样 20 min 来进行同步比较。 试验结果经过统计检验得 t 1. 50 t 20t 30, 故不拒绝 H0, 这表明 采样体积 20、 30 L 的测定结果与 10 L 无显著性差异, 因此在空气采样中, 可以选择 10 L ,也可以选择 20 L 或30 L的采样体积 。而扩大采样体积也相应扩大了 氨在吸收液中的浓度, 在微量氨的监测中 ,为最大程 度地提高氨检测灵敏度, 应采用较大的采样体积采集 空气 。 4 降低方法检出限 纳氏试剂比色法测氨的原理是 用稀硫酸溶液吸 收氨 ,以铵离子形式与纳氏试剂反应生成黄棕色络合 物进行比色 。因此, 首先须确定水中铵的最低检出浓 度,然后根据吸收液体积和采样体积来确定氨的检出 限。在纳氏试剂比 色法测水中铵盐的国标方法 GB747987 中规定 , 该方法的最低检出浓度为 0. 05 mg L ,而国家环保总局发布的水和废水监测分 析方法 四版 和地表水和污水监测技术规范中都 规定为 0. 025 mg L, 为进一步求证该方法的检出限, 依据国标方法 GB T1466893 制备氨的校准曲线以 及20个试剂空白 。 标准曲线方程 Y 0. 004 0. 157X r 0. 999 8 加上校准曲线中的 2 个空白 , 一共制作了 22 个 空白值 ,首先以 Dixon 检验法检验并剔除其中的异常 值,D 0. 5D′ ,D D0. 95 220. 468 ,故判断最大值 65 环 境 工 程 2005年 10 月第 23卷第 5 期 0. 025为异常值, 予以剔除。对剩余 21个空白值进行 统计计算, 得 X0 0. 017, S 0. 0014, 检出限 L03S K 30. 001 4 0. 157 0. 027 mg L ,按 10 mL 吸收液 和30 L 采样体积的方法 方法 B 进行计算, L氨L0 V吸收液 V采 0. 027 10 300. 009 mg m 3 ,此值为国 标方法检出限的 3. 6。 5 2种方法测定低浓度氨样品的比较 现以国标方法A XA 与方法 B XB 同时对采集 的系列低浓度氨样品进行分析 ,结果见附表。 附表 对比不同方法测定系列低浓度氨样品的结果 n 6 mg m3 项目1点位2点位3点位4点位 XA 未检出未检出0. 3160 . 566 XB 0. 0340 . 1290. 3360 . 524 SB 0. 0070 . 0200. 0410 . 054 T1. 191 . 91 T0. 05 5 2. 5712 . 571 评价 接受 H0接受 H0 统计检验结果表明 对于 3 、4 点位的样品, 方 法B 与国标方法的测定结果无显著性差异; 在 1 、 2 点位的低浓度样品测定中 ,国标方法都未能检出, 而方法 B 皆检出 , 且精密性良好。以上检验充分证 明,方法 B 在 0. 25 mg m 3 的低浓度氨样品测定中有 明显的优越性, 其检出限完全适合有关质量标准, 是 对国标方法测定低浓度氨的改进和优化 。 参考文献 1 中华人民共和国国家标准 GB T14668 -93 空气质量 氨的测定. 纳 氏试剂比色法. 北京 中国标准出版社, 2001. 2 中华人民共和国国家标准 GB T18883 -2002 . 室内空气质量标准. 国家环保局、卫生部,2003. 3. 1. 3 中华人民共和国国家标准 GBZ1 -2002 . 工业企业设计卫生标准. 中华人民共和国卫生部. 2002. 6. 1. 4 国家环境保护总局. 水和废水监测分析方法 第 4 版 . 北京 中国 环境科学出版社,1997. 作者通讯处 张素荣 226300 江苏省通州市金沙镇翠园路 10 号 通州市环境监测站 2004- 10-18 收稿 上接第 64页 6 结论 1 碱溶液浓度及用量适当提高可以提高碱激发 即提高了粉煤灰废渣粉胶凝材料的强度 。 2 碱溶液较低时 , 碱溶液激发废渣粉胶凝材料 制备的净浆试块强度接近混凝土试块的强度 ; 碱溶液 达23 时 ,碱溶液激发废渣粉胶凝材料制备的净浆 试块强度接近于混凝土试块的强度 。 3 碱溶液-粉煤灰等废渣可以配置出 28 d 抗压 强度达 44 MPa,抗折强度达 8. 3MPa 同时具有良好工 作性能的钢渣路面混凝土 。 参考文献 1 冯乃谦. 实用混凝土大全. 北京 科学出版社, 2001. 2. 2 S. C. Pala, A. Mukherjeeb, S. R. Pathakc , Investigation of hydraulic activity of ground granulated blast furnace slag in concrete Cement and Concrete Research,2003. 33 1481～ 1486. 3 P. J. Wainwright,N . Rey , The influence of ground granulated blast furnace slag GGBS additions and time delay on the bleeding of concrete, Cement Concrete Composites,2000. 22 253～ 257. 4 S. C. Pala, A. Mukherjeeb, S. R. Pathakc , Investigation of hydraulic activity of ground granulated blast furnace slag in concrete. Cement and Concrete Research,2003. 33 1481～ 1486. 5 季收, 王保君. 粉煤灰在混凝土中的效应及应用. 铁道建筑,2004. 3. 6 C. D . Atis-, U. K. Sevim, F. O . zcan, C. Bilim, O . Karahan, A . H. Tanrikulu, A . Eks, Strength properties of rollercoMPacted concrete containing a non -standard high calcium fly ash. Meterials Letters, 2004. 58 1446～ 1450. 作者通讯处 周佳 100083 北京科技大学土木与环境学院 E -mail zhoujia2005sohu. com 2005- 01-25 收稿 66 环 境 工 程 2005年 10 月第 23卷第 5 期 PROTLAND CEMENTZhou Jia et al 63 Abstract It is presented that alkali activatedslag pavement concrete AASPCismade by activating industrial slag such as steel slag , slag and fly ash etc without any Portland cement as binder and using GGBS gravel and GGBS sand in place of natural gravel and sand as the fine and coarse aggregates. The effect of the proportion of alkali solution on the strength of AASPC is studied. The results show thatwith proper workability the 28 d compressive strength of 44 MPa, bending strength of 8. 3 MPa are obtained. Keywords fly ash, pavement concrete, steel slag , slag and alkali -activated THE EXISTING PROBLEMS OF DETERMINING MICRO -AMMONIA BY NASHI REAGENT COLORIMETRY AND THE SUGGESTIONS ON IMPROVEMENTZhang Surong et al 65 Abstract It is discussed the existing problems of determining micro -ammonia by Nashi reagent colorimetry in the determination of micro- ammonia, it is given the path to lower the s detection limit through reducing the volume of absorbing liquid and adding the sampling volume, and the problem of the overhigh detection limit in the determination of micro -ammonia is solved. Keywords Nashi reagent colorimetry , micro -ammonia, problem and suggestion on improvement APPLICATION OF GRAY RELATIONAL ANALYSIS OF PROMOTING CLEAN PRODUCTION IN ECO-INDUSTRIAL PARKLin Jiquan et al 67 Abstract Clean production is the precondition of construction of an eco-industrial park. Full realization of clean production must be promoted step by step in the exising reconstructive eco -industrial parks. The gray relational analysis was applied in the assessment of promoting clean prouction in an existing reconstructive eco -industrial park. The indicator system and criterion of assessment were set up. The present, medium-term and long term schemeswere respectively set down by the gray relational grade. At the same time, the main problems that restrain the improvement of clean production level of every enterprise were found out by gray relational coefficient. Taking coking enterprises in LongmenIndustry Park for example, the results show that the gray relational grade of No. 4 and No. 9 enterprises exceed 0. 8, in which experiments of carrying out clean production were made, that is to say, they are schemes of promoting clean production at present, and the enterprises are selected in the future, which is the scheme of higher cost for the park. The is a very useful one for assessment of guiding clean production promotion in eco -industrial park with the advantages of uncomplicated principle and reliable results. Keywords clean production promotion, eco -industrial park, gray relational grade and gray relational coefficient APPLICATION OF THE COMBINED TRAPEZOID SPRAY TRAY IN REING SOURWATER STRIPPING COLUMNZhang Wenlin et al 71 Abstract This paper introduces the operational perancesof the combined trapezoid spray tray CTST . In the technical reconstruction of the sour water stripping column for oil refineries, this tray was used instead of F1 float tray in the same column shell. After the technical reconstruction, the treating capacity was increased by more than 80, and the ammonia content of the purified water at the column bottom was lower than 50 mg L. Keywords tray, CTST , stripping column, sour water and technical reconstruction ANALYSIS OF FACTORS AFFECTING PHOSPHORUS REMOVAL EFFICIENCY OF TRIPLE OXIDATION DITCH PROCESSCao Guoping et al 74 Abstract The factor influencing the efficiency of phosphor removal from triple oxidation ditch in Tangshan North Suburb Wastewater Treatment Plant was studied. The result showed that the supernatant reflux from sludge thickener is the main factor causing the low efficiency as well as no anaerobic condition. Some improving processes are also proposed. Keywords triple oxidation ditch, running way, anaerobic phosphorus releasing , aerobic phosphorus absorption and phosphorus removal THE INFLUENCEOFSULFATEREDUCTION ON DENITRIFICATIONUNDER ANOXIC CONDITIONWei Hua et al 76 Abstract It has been conducted an experimental study on the effect of sulfate reduction ondenitrificationunder anoxic condition. The results have demonstrated that the efficiency, the rate and the course of the denitrification processhave been changedby the sulfate reduction process. The efficiency of denitrification decreased from 100 to 81. 4 when the concentration of sulfate was increased. The maximum denitrification rate ranged from 6. 428 mg L min to 4. 04 mg Lmin when the concentration of sulfate solutionwas varied from 0 mg L to 2 000 mg L. Accordingly, the results have shown that the ammonia nitrogen was accumulated during the denitrification process which has been changed by the sulfate reduction process. Keywords sulfate reduction, denitrification stage, ammonium accumulation and anoxic conditions STUDY ONTHE PREPARTION OF MnZn FERRITE CO-PRECIPITATIONPOWDER WITHZn -Mn WASTE DRY BATTERYPeng Changhong et al 80 Abstract Mn -Zn ferrite co -precipitation powder was prepared by the reaction of simultaneous leaching,deep purification and co- 5 ENVIRONMENTAL ENGINEERING Vol. 23, No. 5,Oct. , 2005