Purification of Waste Nutrient Solution Using Activated Carbon. : A Study on the Quantitative Analysi sof Nitrate Nitrogen Contained in Solutions.

硝酸態窒素（NO3-N）溶液をグリースロミイン（GR）硝酸用試薬およびNitra Ver 5 硝酸試薬より発色させ，吸光度の経時変化，および吸光度と濃度の関係を調べた。得られた結果は次のとおりである。1）室温（約15℃）条件下では，GR試薬で発色した溶液の吸光度は試薬添加10分後に時間とともに減少したが，Nitra Ver 5 で発色した溶液の吸光度は静置15分後に安定した。2）GR試薬による発色の場合，0.1～10ppmの濃度範囲において吸光度はNO3-N濃度の増加とともに直線的に増加した。NO3-N濃度が20ppm以上の溶液では不溶物が生成した。3）Nitra Ver 5 試薬による発色の場合，NO3-N 濃度が50ppmまで不溶物の発生が見られなかった。0.1～10ppm と 10～50ppm のNO3-N 濃度範囲において，吸光度とNO3-N濃度の直線関係が得られた。Spectrophotometric determination of nitrate nitrogen contained in solutions was studied using Griess Romijim Nitrate Reagent and Nitra Ver 5 Nitrate Reagent for the color reaction. The changes in the absorbance of solution with time and the concentration of nitrate nitrogen were investigated. In the color reaction with Griess Romijm Nitrate Reagent, the absorbance of solution started decreasing in 10 min, and it increased with the concentration of nitrate nitrogen in the range of 0.1-10 ppm. An insoluble compound was produced in the solution when the concentration of nitrate nitrogen was above 20ppm. In the color reaction with Nitra Ver 5 Nitrate Reagent, however, the absorbance of solution became constant in 15 min, and it had a linear relationship with the concentration of nitrate nitrogen in the range of 0.1-10 ppm, as well as in 10－50 ppm. No insoluble compound was produced in the solution with a concentration of nitrate nitrogen up to 50 ppm