Society of Chemists and Technologists of Macedonia, 25th Congress of SCTM

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Degradation of methyl violet, methyl blue, and methyl red by Fenton process
Besa Mulaj, Marte Raja, Mentor Hamidi, Sevdie Govori, Ramë Vataj, Fetah Podvorica, Flamur Sopaj

##manager.scheduler.building##: Hotel Metropol
##manager.scheduler.room##: Samoil
Date: 2018-09-20 05:30 PM – 07:00 PM
Last modified: 2018-09-13

Abstract


The amount of wastewater is increasing considerably every day. Therefore many cleaning plants have been built in which biological, physical and chemical methods are being applied for removing pollutants from water. The Fenton process is a chemical destructive method for the elimination of organic pollutants from water [1]. It is part of the group of methods for the destruction of pollutants, which are called advanced oxidation processes. It is a mixture of H2O2 and Fe2+ which gives hydroxyl radicals OH a very strong oxidant which oxidizes organic pollutants in water either by transforming them in less harmful byproducts and by mineralizing them [2]. The whole process is performed at pH 3, which is the optimal value for the Fenton process.

Here we have studied the efficiency of degradation of methyl indicators using the Fenton process with different Fenton’s reagent concentration and at different pH values. Methyl indicators are widely used in laboratories, so they are expected to be present in sewage effluents and after they reach the discharge point they enter in water streams becoming part of many other chemical pollutants.

To study the efficacy of the degradation of methyl indicators, 150 ml solution of 0.01 mM concentration of the three types of methyl indicators (methyl violet, methyl blue and methyl red) were prepared, and the pH was regulated to 3 with 0.1 M sulfuric acid, then Fenton Reactive  (H2O2 + Fe2+) is added. At that moment, methylindicator oxidation from hydroxyl radicals began. During the reaction time, samples were taken from the system and analyzed by UV-Vis spectrophotometer in order to monitor the degree of oxidation of the methyl indicators. From the experiments it has been found that the increase of H2O2 and Fe2+ concentrations increases the rate of organic compound degradation. This is expected because more hydroxyl radicals are produced and consequently more methyl indicators molecules oxidized. When pH was changed from the optimal value, and particularly when it was set at values over 3 (4 and 5) the degradation rate lowered strongly.

[1] Neyens, E.; Baeyens, J.  A review of classic Fenton’s peroxidation as an advanced oxidation technique, Journal of Hazardous Materials, 2003, B98, 33-50.

[2] Brillas, E.; Sirés, I.; Oturan, M.A. Electro-Fenton process and related electrochemical technologies based on Fenton’s reaction chemistry, Chem. Rev. 2009, 109, 6570-6631.

 


Keywords


Fenton process, hydroxyl radicals, methylindicator, degradation.