Oxidation Of Cationic Red X-GRL Dye By UV, Ozone, And Ozone Combined With UV

In this research, wastewater containing Cationic Red X-GRL dye was treated by UV, ozone, and ozone combined with UV, respecively. After determining the OH indirect reaction rate constant kR, the radiation flow rate of UV lamp P253.7, the volumetric mass transfer coefficient kLa, and the effective length of the radiation in photochemical reactor L, the influence factor, mechanism., kinetics, and modeling were investigated for these three processes. UV photooxidation researchIn an immersion photochemical reactor equipped with monochromatic UV light of 253.7nm, the direct photodegradation of Cationic Red X-GRL was studied varying different process parameters, including temperature, pH, concentration of the radical scavenger, light intensity of the lamp, initial concentration of the dye, feeding gas flow rate, and the concentration of the dissolved oxygen. The photodegradation rate equation was derived from a proposed photodegradation mechanism. The quantum yield of reaction was determined from Line Source Spherical Emission Model (LSSE Model), which describes the radiation flow rate absorbed by the solution in the photodegradation process.In the presence of dissolved oxygen, there are four possible photodegradation pathways of Diacryl Red X-GRL under the UV radiation of 253.7 nm in the presence of dissolved oxygen: homolysis of excited dye to radicals; electron transfer of excited dye to form radical dye cation; decomposed by superoxide radical anion; and decomposed by singlet oxygen.The overall quantum yield is a function of temperature, pH, concentration of TBA, and concentration of dissolved oxygen. After non-linear regression analysis, the overall quantum yields can be correlated to a function of the temperature, pH, concentration of TBA, and concentration of dissolved oxygen in a modified Arrhenius expression:with activation energy Ea of 11.298 kJ mol-1.As designed for resisting to UV photodegradation, the quantum yield of dye is very low (at the magnitude of 10-3 mol einstein-1), UV cannot treat the dye easily. O3 oxidation research1. In a semi-batch reactor, experiments of Cationic Red X-GRL degradation by ozonation were developed varying ozone gas flow rate, initial Cationic Red X-GRL concentration, temperature, and pH. When the formation of intermediates and the variation of pH, TOC, and nitrate ion during the ozonation were investigated by the use of some analytical instruments such as GC/MS, GC, and IC, the probable degradation mechanism of the Cationic Red X-GRL in aqueous solution was deliberated with the aid of Austin Model 1 Molecular Orbit (AMI MO) calculations. The N(12)-C(13) site in Cationic Red X-GRL, instead of the N(6)-N(7) site, is found to be the principal site for ozone cycloaddition in the degradation processes. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one becomes the form of an amine compound, and the rest four are transformed into two molecules of nitrogen. In the course of the ozonation of Cationic Red X-GRL, the direct attack of ozone is the main decolour effect.2. The ozonation of Cationic Red X-GRL in the presence of TBA, a scavenger of hydroxyl radical, was studied with variation of the ozone gas flow rate, initial Cationic Red X-GRL concentration, temperature, concentration of TBA, and pH.The effect of pH and temperature to conversion of dye are ambiguous, while the ozone gas flow rate can increase the conversion of dye. The conversion of dye was decreased with the increasing concentration ofTBA.The homogeneous experiments performed by mixing separately aqueous solutions of ozone and dye lead to stoichiometric ratio of 4 moles of ozone consumed per mole of dye reacted at various pHs.By the evaluation of the liquid mass transfer coefficient, the interfacial area, and the stoichiometricratio between ozone and Cationic Red X-GRL, the rate constants and the kinetic regime of the reaction between ozone and Cationic Red X-GRL were investigated by applying the experimental data to a...