Pillared Bentonite -Fenton Mechanism Of Oxidative Degradation Of Dye Wastewater Study

In this dissertation, the acid brilliant scarlet3R was chosenas research object. Experimental research has been operated indegradation of simulative dyestuff wastewater with the Fe-Bentonite andFenton oxidation joint application. In this paper, there were four aspects:(1) The original bentonite was purified and Na-modified, then theNa-modified bentonite was modified with Fe3+to get iron column bracedbentonite. The modified bentonite were characterized by IR, electronmicroscope scanning, etc.(2) The degradation characteristics and reactionconditions of simulative dyestuff wastewater were studied particularlyunder combined process.(3) The degradation mechanism and pathwaysof pollutants using iron-carbon micro-electrolysis and Fenton reaction arealso discussed.Achievements via experiments and analyses are acquiredas follow：(1)The reaction temperature had the biggest influence on thetreatment results, followed by pH, reaction time and dosing quantity inthe treating simulative dyestuff wastewater system using Fe-Bentonite.According to the experimental results, the best treatment conditions are asfollows: the pH value is3, the dosing quantity1.0g, reaction temperature40℃, the reaction time40min. The chromaticity and COD removal rateare97.73%and88.62%under the optimal conditions.(2)The correlation coefficients (R2) for Langmuir isotherm adsorptionequation model are closer to1.00, with the best the linear correlationwhile the linear correlation of Freundlich equation is little poorer. Theseillustrate that the sorption for acid brilliant scarlet GR on modifiedbentonite corresponds to Langmuir isotherm adsorption equation model,belonging to mono molecule layer adsorption. The reserch of kinetics ofadsorption on Fe-Bentonite illustrate that the correlation coefficients forthe pseudo second-order kinetics model is R2=0.9995, with the bestcorrelation.(3) The optimal reaction conditions of treating simulated wastewaterusing Fe-modified bentonite-Fenton oxidation are as follows:the pHvalue3,the Fe-modified bentonite dosage0.6g,the dosing ratio5:2, the room temperaturethe and the reaction time60min.The chromaticityremoval rate is96.73%under the optimal conditions.(4)The degradation pathways of the acid brilliant scarlet3R dyewastewater with Fe-modified bentonite-Fenton oxidation in jointapplication have been studied by using UV, IR and GC-MS Spectraanalysis. The azo conjugate chromogenic system of acid brilliant scarlet3R molecular was completely destroyed, with the naphthalenering-opening reaction. The acid brilliant scarlet3R dye degradationprocess was surmised based on the comprehensive analysis of variousspectrum garaph.(5)The leaching of iron ions and the effection of dye degradation dueto the leaching of iron ions were investigated under different reactionconditions.It was observed that the lower the pH value is,the more theleaching of iron ions is. The leaching of iron ions is least and thedegradation effect of dye is best at pH3. The conclusion was thattheintermediate products could accelerate the leaching of iron ions in theFe-pillared bentonite and Fenton oxidation system duo to theexperimental analysis.The leaching of iron ions has a tendency that ironrelease quantity increased first then decreased along with reaction timebecause the iron ions were readsorbed onto bentonite. This is indicatedthat the Fe-pillared bentonite has good stability and the leaching of ironions do not cause secondary pollution.