焦化厂蒸氨废水中氨氮快速检测方法的研究

Research on rapid detection method for ammoniacal nitrogen in ammonia distillation wastewater at coking plants

蒸氨废水中存在较高浓度的S^(2-),严重影响离子选择性电极法测定结果的准确性,因此,焦化厂蒸氨废水中氨氮的检测一般采用纳氏试剂比色法,但该方法操作过程烦琐、测定时间长,分析结果滞后。鉴于此,研制了全固态铵离子选择性电极,通过向废水中加入适量的醋酸锌消除S^(2-)的干扰,进而建立一种适用于蒸氨废水中氨氮快速检测的电化学分析方法。调节水样的pH至4~7,加入适量的醋酸锌,测量铵离子选择性电极与Ag/AgCl参比电极间的电位差,通过标准曲线即可快速获得水样中氨氮的浓度。该方法对氨氮的检测线性范围为0.14~1400 mg/L,检出限为0.011 mg/L,相对标准偏差RSD为1.14%~3.02%,加标回收率为99.85%~104.18%。该方法操作简便,测定时间短,可快速分析焦化厂蒸氨废水中的氨氮,并具有开发氨氮在线监测装置的良好应用前景。

There is a high concentration of S^(2-)in ammonia distillation wastewater,which seriously affects the accuracy of the determination results by ion-selective electrode method.Therefore,Nessler's reagent colorimetry is generally employed to detect ammoniacal nitrogen in ammonia distillation wastewater at coking plants,but it has a complicated operation process,needs long determination time and obtains analysis results lagged.Thus,an all-solid ammonium ion selective electrode is developed,and an electrochemical analysis method is established for rapid detection of ammoniacal nitrogen in ammonia distillation wastewater through adding a moderate amount of zinc acetate into wastewater to eliminate the interference of S^(2-).Adjusting the pH of wastewater sample to 4-7,adding a moderate amount of zinc acetate,then the potential difference between ammonium ion selective electrode and Ag/AgCl reference electrode is measured,and finally the concentration of ammoniacal nitrogen in wastewater sample is obtained by means of standard curve.The linear detection range of ammoniacal nitrogen by this method is 0.14-1400 mg·L^(-1),the detection limit is 0.011 mg·L^(-1),the relative standard deviation RSD is 1.14%-3.02%,and the recovery rate is 99.85%-104.18%.This method is easy to operate,needs a short detection time,can rapidly analyze ammoniacal nitrogen in ammonia distillation wastewater at coking plants,and shows a good application prospect in developing ammoniacal nitrogen online monitoring device.