Research On Degradation Mechanism Of Reactive Blue4by Natural Manganese Ore

Dyes are a kind of fine chemical products which are widely used in human life.Dyeing wastewater and its degradation intermediates are proven biological toxicity andpotential induction effect. Methylene blue and reactive blue4are commonly used in thesimulated dyeing wastewater, and have wide representation in the study of dyingwastewater degradation research. Natural manganese minerals are content large in thenature of minerals, most of them have the fundamental part of MnO₆octahedron.Manganese ore is extensively involved in the biochemical conversion of the Earthelements, in addition to adsorption, the environmental attributes of the manganese orealso includes the flocculation and precipitation, ion exchange, surface complexation,redox, catalytic role. The natural manganese ore treatment of refractory organic waterresearch is also focused on the removal rate, optimal reaction conditions etc. Rarereports are on the degradation mechanism of manganese for specific refractory organicwastewater. In this issue, the treatment effect, degradation and decolorizationmechanism of degradation of reactive blue4by natural manganese ore were explored.For the subsequent use of natural manganese ore treatment of dye wastewater, or otherpractical application of refractory organic wastewater, the research expects to provide aresearch base and theoretical support.By XRD and XRF analysis, Qianxi manganese ore samples from Tangshan containrancieite, johannsenite, dolomite and quartz and other minerals, the content ofmanganese is8.27%, and relative content of MnO₂in the manganese ore is low. Thepoint of zero charge（PZC）is1.9, the mineral type is the carbonate poor manganese ore.The comparative experiment was used in the research of methylene bluedegradation by natural manganese ore. After80min reaction, the removal rate ofmethylene blue solution was nearly90%, Reaching50%removal rate need13min.Comparing with several other reaction combinations—activated sludge, quartz fillermixed activated sludge, ceramic fillers mixed activated sludge, iron ore mixed activatedsludge, iron ore, manganese ore mixed activated sludge, the removal rate of naturalmanganese ore was just lower than the combination of manganese ore mixed activatedsludge.We used oscillation experiment to study the degradation of reactive blue4bynature manganese ore. After24h reaction, the removal rate of reactive blue4solution is 65.504±0.455%, reaching50%removal rate need12h. During the reaction process, theconductivity of the solution was almost invariant, pH rose sharply in the first two hoursof the reaction process, after two hours, the pH reached7and was invariant then.During the reaction process, the TOC removal rate reached24.76%. Through theanalysis of experimental data, we found that natural manganese ore degraded reactiveblue4reaction corresponded to second-order kinetic characteristics, the fitting kineticequation is y=264.7x+157.6，R²=0.993. According to the UV-visible spectrum, weinferred reactive blue4decolorization process began with the broken of unsaturatedconjugated bond of dye molecules chromophore, anthraquinone groups were firstdestroyed, the benzene ring, the triazine group, the sulfonic acid concentration wasdecreased gradually. According to the IR spectra of the reaction solution and manganeseore, we inferred that functional groups of C=O and C-N in the reactive blue4were firstattacked, possible degradation products of dye macromolecule were phthalic acid,2,3-dihydroxy-sulfonate,2-amino,4-hydroxy-sulfonate,4,6-dichloro-1,3,5-triazin-2-ammonia,etc. Parts of the functional groups were degraded tocarbon dioxide and water. We analysis XRD results of the manganese ore in thereaction and found that there was no significant change compared to the manganese orewhich was not participate in the reaction. Mn²⁺concentration in the reaction solutionwas in an upward trend, the Mn³⁺, Mn⁴⁺on the surface of manganese ore was reduced toMn²⁺in the degradation reaction. Natural manganese ore degrading reactive blue4mainly depended on the oxidation-reduction reaction on the ore surface.This study provided a research basis and theoretical support for the subsequentusing natural manganese ore to degrade dyeing wastewater treatment and otherrefractory organic water.