纳氏试剂分光光度法测氨氮优秀PPT

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,*,水中氨氮含量的测定,中国环境管理干部学院,环境技术探讨与试验中心,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,一、概 述,1、与氮有关的水质指标,（1）,总氮,：,紫外分光光度法测定,（2）,凯式氮,：,有机氮+氨氮 蒸馏滴定方法测定,（3）,氨氮,：,NH,3,+,NH,4,+,（组成取决于溶液的,pH,值,),（4）,亚硝酸盐氮,（,5,）,硝酸盐氮,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,2、,水处理系统中氮的转化过程：,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,3、测定含氮物质的缘由,测定水中各种形态的氮化合物，评价水体被污染和“自净”状况:,当发觉水中氨氮或有机氮的浓度很高时，表明水体刚刚受到污染，其潜在的危害较大，,当水中硝酸盐氮浓度高时，表明水已经过生化自净。,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,二、试验目的,（1）了解氨氮的几种测定方法,（2）驾驭分光光度计的运用、标准曲线的绘制及有关计算方法,（3）熟悉纳氏试剂光度法测定氨氮的原理及过程,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,三、试验方法的选择,氨氮的测定方法：,纳氏试剂比色法,苯酚次氯酸盐比色法,水杨酸次氯酸盐比色法,电极法,具有操作简便、灵敏等特点。,水中钙、镁和铁等金属离子、硫化物、醛和酮类、颜色，以及混浊等均干扰测定，需作相应的预处理。,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,四、,纳氏试剂分光光度法原理,HgI和KI的碱性溶液与氨反应生成淡红棕色胶态化合物，此颜色在较宽的波长范围内具猛烈吸取。通常测量用波长在410-425nm范围。,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,五、试验步骤,1、水样预处理,絮凝沉淀法：,取100ml水样（进水、出水、无氨水）,1ml 10%硫酸锌溶液,25%的NaOH溶液，调整pH至10.5左右，混匀,静置沉淀,过滤（,弃去初滤液20ml,）,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,2、校准曲线的绘制：,（1）配置铵标准运用液：,移取5.00ml铵标准贮备液于500ml容量瓶，定容。此溶液浓度为0.010mg/ml。,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,（2）标准色列配置：,移取0、0.50、1.00、3.00、5.00、7.00和10.0ml铵标准运用液于50ml比色管中，加水至标线；,1.0ml酒石酸钾钠溶液，混匀；,1.5ml纳氏试剂，混匀；,放置显色10min后，在波长420nm处，用光程10mm比色皿，以蒸馏水为参比，测量吸光度。,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,（3）绘制标准曲线,由测得的吸光度，减去,零浓度空白管的吸光度,后，得到校正吸光度，,绘制以氨氮含量（,mg,）,对校正吸光度的校准曲,线。,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,2、,水样的测定,取适量经预处理后的水样（使氨氮含量,不超过,0.1mg,），加入,50ml,比色管中，稀释至标线，,1.0ml,酒石酸钾钠溶液，混匀；,1.5ml,纳氏试剂，混匀；,放置,10min,后，在波长,420nm,处，用光程,10mm,比色皿，以蒸馏水为参比，测量吸光度。,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,3、计算,由水样测得的吸光度,减去,空白试验的吸光度后，从校准曲线上,查得,氨氮含量（,mg,）。,A,x,=A-A,空白,m,x,由校准曲线查得的氨氮量（mg）,V水样体积（ml）,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,A,x,m,x,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,六、留意事项,（1）纳氏试剂中碘化汞与碘化钾的比例，对显色反应的灵敏度有较大影响。静置后生成的沉淀应除去。,（2）滤纸中常含痕量铵盐，运用时留意用无氨水洗涤。所用玻璃器皿应避开试验室空气中氨的沾污。,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,七、思索题,（1）预处理絮凝沉淀时PH值为何调至10.5左右?,（2）过滤时为什么要弃去初滤液20ml？,（,3,）如何提高校准曲线的精确度？,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,八、分光光度法原理（附）,1、光的吸取定律（朗伯比耳定律）,分光光度计的定量依据是朗伯比耳定律,式中：K比例常数，与入射光的波长及物质的性质有关；,L液层的厚度；,C溶液的浓度。,T为透射度（表征光的透过程度），以百分数表示。,T100%，则A0；,T0%，则A1。,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,2、分光光度计构成,电源开关,波长旋钮,比色皿槽,微安表,拉杆,调百旋钮,调零旋钮,灵敏度调整旋钮,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,Sino-Dutch Demonstration Researcher and Training Centre for Water Treatment,