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Qualitative and Quantitative Analysis of Water
Published in Sreedevi Upadhyayula, Amita Chaudhary, Advanced Materials and Technologies for Wastewater Treatment, 2021
A known quantity of potassium dichromate (K2Cr2O7) and sulfuric acid (H2SO4) are added to the water sample. Organic matter reacts with this reagent and Cr(IV) in K2Cr2O7 is converted to Cr(III). Excess dichromate is titrated with ferrous ammonium sulfate until all the excess oxidizing agent has been reduced to Cr(III). Ferroin indicator is used and the color changes from blue-green to reddish-brown at the end point.
Oxygen Demand, Chemical
Published in Pradyot Patnaik, Handbook of Environmental Analysis, 2017
1,10-Phenanthroline (ferroin), which is used as an indicator in this titration, forms an intense red color with Fe2+, but no color with Fe3+. When all the Cr6+ is reduced to Cr3+, Fe2+ reacts with the indicator forming the ferroin complex. The color of the solution changes from greenish blue to reddish brown signaling the end point of titration.
Propositure of maximum permissible limits for environmental assessment and classification of materials stabilized by solidification incorporated with oil waste
Published in Environmental Technology, 2022
Joelma Dias, André Luiz Fiquene de Brito, Ana Cristina Silva Muniz
From the leached liquid and the solubilized liquid, the COD test was performed. Initially, 1.5 ml of standard potassium dichromate digestion solution, was added to a test tube (this solution is previously prepared from potassium dichromate, mercury sulfate, concentrated sulfuric acid and water), 2.5 ml of the liquid to be determined COD and 3.5 of the catalyst solution (prepared from silver sulfate and sulfuric acid). Then the blank test was prepared from 2.5 ml of distilled water, 1.5 ml of digesting solution and 3.5 ml of catalyst solution. The test tubes were closed and homogenized, and then placed to digest, in an digester block, for 2 h at 150o C. After that time, the tubes were removed from the digester and placed at room temperature to cool. Then these samples were transferred to an Erlenmeyer flask and supplemented with distilled water to a volume of 25 ml and added a drop of the ferroin indicator. The sample was then titrated with the standard solution of 0.025 N ammoniacal ferrous sulfate, the volume of the spent ferrous solution was called VPS. The volume of the ferrous solution spent in titrating the blank test was called VBP. A standard sample was also prepared from 1.5 ml of the digesting solution, 15 ml of distilled water, 3.5 ml of concentrated sulfuric acid and a drop of ferroin. This standard test was titrated and the volume of ferrous solution spent was called VSP. COD was obtained using the following equation:
Electrochemical degradation of psychoactive drug caffeine in aqueous solution using graphite electrode
Published in Environmental Technology, 2018
Selvendiran Periyasamy, Muthukumar Muthuchamy
Analytical-grade chemicals were used as received. Caffeine was purchased from Sigma-Aldrich (USA). The physiochemical property of caffeine is shown in Table 1. Sodium hydroxide, sodium sulfate, sulfuric acid, ferrous ammonium sulfate, mercuric sulfate, silver sulfate, ferroin solution, dichloromethane were obtained from Hi media (Mumbai, India). All solutions were prepared in double distilled water and the pH value was adjusted by adding HCl (5%, v/v) and NaOH (5%, w/w). HPLC-grade acetonitrile and water were purchased from Sigma-Aldrich and used without any further purification.
Oxidation-precipitation of magnetic Fe3O4/AC nanocomposite as a heterogeneous catalyst for electro-Fenton treatment
Published in Chemical Engineering Communications, 2020
Pegah Nazari, Neda Askari, Shahrbanoo Rahman Setayesh
Iron (II) sulfate heptahydrate, sodium nitrate, sodium sulfate, ammonium hydroxide (28%), sulfuric acid, nitric acid (65%), hydrochloric acid, sodium hydroxide, potassium dichromate, mercury (II) sulfate, silver sulfate, ferroin reagent, iron (II) ammonium sulfate hexahydrate, hydrogen peroxide solution (35%, W/W), activated carbon, 1, 10 orthophenanthroline, potassium biphthalate, salicylic acid, potassium iodide, ammonium molybdate, isopropanol, benzoquinone, and catechol were all purchased from Merck (Darmstadt, Germany).