Preparation Of Iron-nickel Alloy Films And Their Degradation Performance On Azo Dye Wastewater

In recent years,the rapid development of industry has led to increasingly serious pollution of limited freshwater resources.Zero-valent iron nanoparticles have received much attention due to their unique physical and chemical properties in applications to solve environmental problems.However,due to the high chemical activity and size effect of nanoparticles,zero-valent iron nanoparticles are highly susceptible to excessive oxidation and agglomeration,and these problems greatly limit their practical applications.In this paper,Ni alloying was adopted to enhance the oxidation resistance of zero-valent iron nanoparticles and further improve their magnetic properties.Meanwhile,graphene was added during the nucleation growth of nano-alloy particles,and GR/FeNi alloy nanocomposite powder was constructed by in situ growth of nano-FeNi alloy particles on graphene sheets using liquid-phase reduction method,which not only effectively solved the problem of excessive agglomeration of nanoparticles,but also enhanced the degradation performance of graphene The excellent electron transfer capability of graphene enhances the degradation performance of the composite powder;a dense FeNi-M alloy film was prepared by directional magnetic field-assisted wet chemical film formation method using copper foil as the substrate.Finally,the degradation properties of azo dye wastewater were studied for GR/FeNi alloy nanocomposite powders and FeNi-M alloy films.It was shown that GR/FeNi alloy nanocomposite powder with bimetallic electron donor and graphene with accelerated electron transfer mediator can effectively degrade high concentration（250 mg/L）of CR azo dyes in a short time（150 min）,and the appropriate increase of temperature and acidic conditions is beneficial to improve the degradation performance.The best degradation performance was obtained with 10%GR/FeNi alloy nanocomposite powder,whose degradation efficiency was 99.45%at 150 min,and the degradation rates were 1.60and 1.48 times higher than those of 5%and 20%.This is related to the growth of FeNi alloy nanoparticles on lamellar graphene.With fewer nanoparticles,the graphene stacked together will form a graphite-like structure through a very strong-bonding stacking effect,resulting in a lower electron transport rate;too many nanoparticles will produce severe agglomeration and reduce the specific surface area of the composite powder.The FeNi alloy film effectively avoided the disadvantage of secondary pollution caused by the residual nanoparticles in the water,and achieved the degradation and adsorption of Congo red in the water,with a degradation efficiency of 99.5%at 48 h.Its apparent degradation reaction rate constant(k_obs of 0.10982 h^-1)was 2.1 and 7.5times higher than that of the ordinary FeNi alloy film(0.05147 h^-1)and Ni film(0.01465 h^-1)2.1 and 7.5 times the apparent degradation reaction rate constants.The films still had more than 90%removal rate after 5 cycles and possessed excellent cycling performance;analysis of the degradation mechanism and pathway of CR azo dyes by FeNi-M alloy films showed that the decolorization of CR azo dyes was mainly due to the breakage of the azo double bond（-N=N-）,with Fe atoms mainly responsible for providing electrons in the alloy films and Ni atoms also providing small amount of electrons.GR/FeNi alloy nanocomposite powder and FeNi-M alloy film provide effective degradation of CR azo dyes with simple subsequent recycling operation,which is simple,green and low-cost wastewater treatment technology with broad application prospects.