Optimization of Distillation Conditions for Detecting Ammonia Nitrogen in Water Using Nessler's Reagent Spectrophotometry
In the actual test,it was found that the recovery rate of ammonia nitrogen was low when the water sample was pretreated by distillation according to the Determination of Ammonia Nitrogen in Water Quality-Spectrophotometry of Nessler's Reagent(HJ 535-2009).Use 20 mL boric acid solution as the absorption solution to absorb and distill ammonia gas.By adjusting the pH value of the effl uent,determine the effect of different pH values on the ammonia nitrogen recovery rate.The results show that when the pH value of the effl uent was less than 9.0,the absorption efficiency is lower and the ammonia nitrogen recovery rate is less than 80%;When the pH value range of the effl uent is 9.5～10.0,the recovery rate is 84.9%～99.4%;When the pH of the effl uent is 10.5,the recovery rate is 96.7%～103.6%,which is higher in recovery rate and precision.The optimized method is used to detect both the standard sample and the actual water sample,and the results of the standard sample are within the standard value range.The recovery rates of the actual water sample are between 95%～105%,indicating good accuracy.
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