FeNi alloy films prepared by directional magnetic field assistance and their degradation and adsorption on azo dyes

Abstract

Synthetic dyes in the aquatic environment caused various ecological and health problems that are detrimental to sustainable development. To solve these problems, we designed a dense Fe3Ni2 phase alloy film (FeNi-M) on copper substrate by the directional magnetic field-assisted wet chemical film formation method. The degradation and adsorption of Congo red (CR) in water were achieved by using the surface activity of the film. The degradation rate of FeNi-M alloy film reached 99.5% at 48 h and the kobs is 0.10982 h−1, which is 2.1 and 7.5 times of FeNi alloy film (0.05147 h−1) and Ni film （0.01465 h−1）, respectively. The degradation processes of all three films were in accordance with the pseudo-first-order kinetic model. In addition, FeNi-M alloy films have excellent cycling performance with more than 90% removal rate after 5 cycles. We also discussed the possible degradation mechanism and pathway of CR. We speculated that the main part of alloy responsible for providing electrons were iron atoms and very few electrons were produced by nickel. However, nickel was beneficial to increase the activity of iron atoms and played a catalytic role, thereby greatly enhancing the efficiency of iron atoms on the reaction.