Title: TN
Date:
Student no.
Name:
Experimental Objectives:
Determination of Total Nitrogen
Experimental Theory:
The procedure used in the determination of the total Nitrogen (TN) should employ unfiltered and filtered samples. Total Nitrogen can be defined as the sum of ammonia-nitrogen, nitrite-nitrogen, nitrate-nitrogen, and organically bonded Nitrogen. It should never be confused with TNK, which refers to the amount of ammonia-nitrogen and organically bound Nitrogen. However, it does not involve nitrate-nitrogen or nitrite-nitrogen. The TN sometimes has to be controlled as an effluent parameter purposely for industrial and municipal wastewater plants. Treatments containing limits of TN would usually require to denitrify as well as nitrify to achieving the limit of TN. Nitrogen is found in wastewater in the form of four categories but with the exclusion of nitrogen gas. Each and every main form has to be analyzed separately, having the Total Nitrogen being calculated from the number of those forms. Measuring organic Nitrogen in the lab is a challenge because one requires digestion of the sample before analysis is performed. This helps in conversions of organic Nitrogen to a particular form, which is more amenable for the study. The reasons for doing analysis for Total Nitrogen are because of being a good indicator of the quality of water, to get clues for nitrogen sources, comparing the affluent and influent wastewater, and lastly determination of wastewater treatment efficiencies. The principle of the Kjeldahl method was used in the experiment for the determination of Total Nitrogen.
Reagent and Experimental apparatus:
- Kjeldahl apparatus
- boric acid
- water sample
- potassium or sodium sulphate
- sulphuric acid
- NaOH
- Deionised water
Experimental Methods
There were three steps involved. Indigestion, there is the breaking of organic bonds resulting conversion of Nitrogen to ammonium. Next, a digestion mixture was added. The reason was to increase the temperature of digestion. The idea of digestion temperature was set to be 370 degrees. The ratio of sulphuric acid used defined its boiling point. Catalyst. The sample was weighed (homogeneous), then sulphuric acid was added, but everything was added except the sample. The digestion was set at 370 degrees till the mixture was very clear. After digestion, followed steps were distillation and titration. During distillation, three processes took place, cooling of digested sample, dilution and preparation for receiving vessel. Also, sodium hydroxide was added to the distillation process. Titration was the last step whereby; potentiometric titration was considered. During titration, the condensate was titrated together with a sulphuric acid standard solution up to the endpoint of pH of around 4.65. Getting a precise measurement of total Nitrogen in one’s sample, one has to measure every nitrogen form as well as adding then all together. The instruments make use of thermal decomposition for the sample used as well as the subsequent measurement of the gases that evolved either by chromatography.
Results
The percentage of Nitrogen was calculated using the
(Consumption -Blank) multiplying by 1.4007 x n x 100}/ the sample size that was used.
1.4007 represents a volumetric solution
N = Normality of Acid
Discussion:
Several situations exist where it is essential to know the total nitrogen content within a water system. However, the objective of the experiment was achieved. There is a need to control and monitor nitrogenous contaminant levels, especially in industrial effluents, to prevent any kind of stream pollution. During the industrial process, control of total Nitrogen depends on the aqueous medium used. Also, freshwater supplies should be determining the total nitrogen content for which it must be specified, depending on the usage. Using the method of Kjeldahl Nitrogen only included organic Nitrogen and ammonia but did not include nitrite and nitrate nitrogen. Therefore, it was recommended to use salicylic acid, although it does not provide the exact nitrite nitrogen percentage to be recovered. The method needs time, especially in the procedural part, for distillation and digestion of the used sample. There is also a need for great care, which should be exercised to prevent the contamination of low parts-per-million levels of Nitrogen.
Total nitrogen content, specifically for inorganic and organic, should be determined. Total Nitrogen for both organic and inorganic should be 1.0mg/L. Therefore, if the level is zero percent, the condition is natural., If it is 0.1 to 10 percent, it has color green showing that water is in good condition. Also, between 10.1 to 50 percent, the condition state is yellow, indicating a fair situation. With more than 50 percent, the condition is termed as a cautionary as there is a red color. Studies for digestion time were done to determine the optimum time for the pressure vessel that was used. It should be known that 0.5ppm Nitrogen is present in seawater. The amount as bee determined as being low at the surface closely to 0.1 ppm. River water concentrations contain the most reliable content despite having an approximate of 0.25pm generally. Concerning various properties of water, several organic nitrogen compounds might be found. Total Nitrogen shows the amount of inorganic and organic nitrogen compounds present in the tested water sample. The solubility of Nitrogen might differ between its compounds.
References
“Nitrogen (N) And Water.” Lenntech.Com, 2020, https://www.lenntech.com/periodic/water/nitrogen/nitrogen-and-water.htm#:~:text=The%20amount%20is%20clearly%20lower,nitrogen%20compounds%20may%20be%20found.
“Total Nitrogen | SEAWA.” Seawa.Ca, 2020, http://seawa.ca/state-of-the-watershed/sow-indicators/total-nitrogen/.
“Total Nitrogen In Wastewater.” CHEMSCAN, 2020, https://www.chemscan.com/total-nitrogen-in-wastewater.html.