Degradation Of Azo Dyes By Iron-based Nano-powders And Amorphous Films

In recent years,due to the rapid development of printing and dyeing industry,the discharge of printing and dyeing wastewater dominated by azo dyes has caused serious water pollution.Based on acid orange,methylene blue,Congo red three kinds of azo dye as a dye wastewater pollutants simulation system to study the zero-valent iron nanoparticles,Fe base amorphous thin film materials such as the reaction principle and degradation effect,and through the regulation of alloy composition,changing environmental conditions such as the influence of factors on the degradation of performance in a series of research,now get the following conclusion:nZVIN nanometer powders were prepared by simple,efficient and non-pollution liquid phase reduction method.The powders have unique core-shell structure,particle size is about 60nm,and excellent antioxidant performance,which solves the problem that nZVI powders are easy to be oxidized and hard to be stored.At the same time,the powder has good magnetic properties and can be separated and recovered by simple magnetic field treatment.The unique core-shell structure of nZVIN powder can adsorb CR molecules in the outer layer of the solution,while the zero-valent nano-iron inside can hydrocatalyze CR molecules to degrade dyes and decolorize the solution.In the decolorization treatment of dye wastewater simulated by Congo red(CR)dye,nZVIN powder can maintain a removal rate of more than 90%for dye wastewater with different pH value(7.0-11.5)and initial dye concentration(50-200 mg/L),which has a broad application prospect in the treatment of azo dye wastewater.By studying the effects of temperature,pH value and hydrogen peroxide concentration of the fenton reaction on the degradation of methylene blue and acid orange dye by FeSiB amorphous film,it was found that the PH value between 3-4 could ensure the full generation of hydroxyl radicals for the optimal degradation efficiency(92%).Too high or too low concentration of hydrogen peroxide is not conducive to the fenton-like reaction,and the concentration of 1-5mm is the highest reactivity.Temperature increase can significantly increase the dye degradation rate,and through the first order reaction kinetics and Arrhenius formula calculated Fe-Si-B amorphous thin film for methylene blue(MB)and acid orange(AO)? two dye degradation reaction activation energy of 33.2 KJ/mol,respectively,and 34.4 KJ/mol.In addition,the degradation effects of different Fe-based amorphous films on dye wastewater were studied.The degradation of dye-acid orange and methylene blue by Fe-Si-B,Fe-Co-Si-B and Fe-Si-B-P-Cu amorphous films was compared.It was found that the degradation of azo dyes by Fe-Co-Si-B quaternized amorphous films with Co in the optimal reaction conditions was better than that of the common Fe-Si-B amorphous films(15min,11 min)for over 90%of degradation time(13min,9min).However,the reaction rate of Fe-Si-B-P-Cu amorphous film with P and Cu added decreased significantly(24min,15min).It was found that the recyclability of Fe-Co-Si-B and Fe-Si-B-P-Cu amorphous films was significantly better than that of Fe-Si-B amorphous films through several cyclic experiments and the verification of scanning electron microscopy.It was proved that the corrosion resistance of amorphous films to azo dyes degradation was significantly enhanced by doping of appropriate component components.