Iron and aluminum composite capable of adsorbing trivalent arsenic and application of iron and aluminum composite

The invention relates to an iron and aluminum composite capable of adsorbing trivalent arsenic. The iron and aluminum composite is prepared through the following method including the steps that firstly, a hydrogen dioxide solution is added into a ferrous sulfate heptahydrate solution at the mass ratio of ferrous iron to hydrogen dioxide being 1:(0.8-1.2), and a mixed solution is obtained after a reaction; secondly, roasted aluminum oxide is added into the mixed solution at the mass ratio of iron to aluminum being 1:(0.15-1.5), and an iron and aluminum mixed solution is obtained; thirdly, the iron and aluminum mixed solution is subjected to constant-temperature oscillation, drying and grinding, and then the iron and aluminum composite is obtained, wherein the pH of the mixed solution or the iron and aluminum mixed solution is regulated to range from 5.5 to 6.5 in the preparing process. Compared with a material prepared through a biological method, the preparing method is simple, high in operability and more beneficial to industrial production.