实验目的 掌握水质分析中总磷的测定方法
2.
实验原理 总磷的概念 在天然水和废水中,磷几乎都以各种磷酸盐的形式存在,它们分为 正磷酸盐,缩合磷酸盐(焦磷酸盐、偏磷酸盐和多磷酸盐)和有机结合的磷酸 盐,
采用过硫酸钾消解-钼锑抗分光光度法的方法测定污水处理厂剩余污泥中的总磷,通过实验确定最佳预处理方法,消解方法,过硫酸钾用量等分析条件.结果表明,方法线性良好,实际污泥样品的平行测定的RSD为0.5%～1.1%。
总磷是水体中磷元素的总含量，是水体富含有机质的指标之一。磷含量过多会引起藻类植物的过度生长,水体富营养化,发生水华或赤潮,打乱水体的平衡。
水中总磷的测定可以根据水质分析规定方法进行。
水中的含磷化合物,在过硫酸钾的作用下,转变为正磷酸盐。正磷酸盐在酸性介质中,可同钼酸铵和酒石酸氧锑钾反应,生成磷钼杂多酸。磷钼酸能被抗坏血酸还原,生成深色的磷钼蓝。在700nm波长下,测定样品的吸光度。从用同样方法处理的校准曲线上,查出水样含磷量,计算总磷浓度,用〈P,mg/L〉表示。
原理：
在中性条件下，过硫酸钾溶液在经120℃以上加热，产生如下反应：
K2S2O4+H2O→2KHSO4+[O]从而将水中的有机磷、无机磷、悬浮物内的磷氧化成正磷酸。 在酸性介质中，正磷酸与钼酸铵反应，在锑盐存在下尘成磷钼杂多酸后，立即被抗坏血酸还原，生成蓝色的络合物，在700nm波长下有最大吸收度。
Abstract: total phosphorus in water, nitrogen and COD (chemical oxygen demand) is reflected in the importance of water quality indicators, in general, because of self-purification capacity of water, natural water of nitrogen and phosphorus content and COD value is not high and the trend On the stability. But with the accelerated process of urbanization, urban industrial building high-speed development in recent years, urban sewage and industrial wastewater emissions were rising trend year by year, fertilizer, metallurgy, printing and dyeing, synthetic detergent industries such as wastewater, sewage life Water and water for agricultural use, with a large number of nitrogen and phosphorus compounds, the COD value is high. Through various channels such sewage into the water, all kinds of phosphate in water, organic and inorganic nitrogen content of nitrogen compounds will continue to improve, a direct impact on water quality. Material increase in nitrogen and phosphorus in water, algae and micro-organisms will lead to excessive breeding, large consumption of dissolved oxygen in water. When more than the load of water, will result in decreased water transparency, eutrophication, and other adverse effects, so that the water quality deterioration.
On the other hand, China's annual COD only in the liquid waste generated in the form of environmental emissions of mercury and silver of sulfuric acid on a few tonnes, the environmental pollution caused by the secondary has been not to be ignored. Determination of potassium dichromate and used water samples COD not only time-consuming energy, water back, reagent consumption also great. It can be said that we have been adopted by the COD of the water quality is not consistent with the way the concept of environmental protection.
To sum up, with the water quality of the increasing deterioration of the situation, water quality monitoring in the determination of nitrogen and phosphorus to the improvement of water quality monitoring and protection is of great significance, and improve the existing COD or on the determination of low energy consumption, Reagents used and less time-precise determination of the new, equally positive and important significance.
This article from the multi-pronged approach to study high temperature and high pressure digestion, microwave confined digestion, digestion and a series of heated water bath TP digestion of the total nitrogen, as well as the standard return, microwave digestion and a series of COD determination of the digestion. Through the TP TN COD content of the results of different methods of comparison, and various microwave digestion time and return to standard time that the effect of digestion sample comparison of research, improvement of the original determination, or find a new technology Means to achieve rapid and effective sample decomposition, shorten the time for the purpose of digestion, and can greatly reduce the digestion of the samples in the loss and pollution, improve the determination of precision and accuracy, expanding the scope of application methods, while exploring a new approach And the classic method of comparability, and its practical application in the superiority of developed a variety of water suitable for TP TN COD of the rapid digestion of accurate, the new method is simple system, to improve the water and wastewater monitoring Analysis at the same time, to a certain social benefits.
Key words: total phosphorus (TP); Total Nitrogen (TN); chemical oxygen demand (COD); microwave digestion; optimum conditions
①打开消解系统开关，设定温度为120℃，定时为30分钟，启动消解系统，开始升温。同时对测定系统开机进行预热，预热时间至少10分钟；②准备数支反应管，置于冷却架的空冷槽上。
①准确量取8ml蒸馏水加到“0”号反应管中；②然后分别准确量取各水样8mL，依次加入到其他反应管中。
依次向各个反应管中加入1mL的P1试剂，加盖混匀。
消解器升温完成后，将反应管依次放入仪器消解孔中。按消解系统的【启动/停止】键，开始消解计时，消解系统会自动倒计时提醒。
消解完成后将各样品依次放到冷却架。
将各反应管放到冷却架的水冷槽中（提前在水冷槽中加入自来水）。
①向水冷却完成的各反应管中分别加入1mL P2试剂混匀，30秒后再分别加1mL P3试剂充分混匀；②静置15分钟；③依次倒入对应编号的比色皿。
先将“0”号比色皿（空白溶液）放入主机的比色槽中，并关闭上盖。
按【设置/空白】键，仪器屏幕将如图显示。然后将“0”号比色皿（空白溶液）从仪器中拿出。
再将“1”号比色皿，放入比色槽中，并关闭上盖。此时屏幕上所显示的结果即为“1”号样品的总磷值；其他样品同上，依次放入比色槽后，关闭上盖，仪器将显示出该样品的总磷值。
