The invention belongs to the technical field of composite materials and discloses a preparation of a
magnesium-aluminum
bimetal oxide modified
straw biomass charcoal composite material. The preparation method comprises the following steps of: soaking crushed straws in a
sodium hydroxide solution, removing impurities, cleaning the crushed straws with deionized water to obtain yellow filamentous fibers, adding the yellow filamentous fibers into an
acetic acid acidified
sodium chlorite solution, performing decolorizing, cleaning, and
drying to obtain SF; preparing an
aluminum nitrate solution, soaking the SF for 4-24 h and then performing filtering, performing high-temperature
calcination in a
nitrogen atmosphere to obtain Al2O3 / SF; and dissolving
magnesium nitrate hexahydrate, Al2O3 / SF and
hexamethylenetetramine in deionized water according to a
solid-to-
liquid ratio of (0.3-3.0) g: (0.2-1.8) g: (0.05-1.3) g: (50-200) mL, reacting at 60-180 DEG C for 6-48 hours, and calcining at high temperature in the
nitrogen atmosphere to obtain Mg-Al / SF. According to the method, the waste straws are used as a
biomass resource, the Mg-Al / SF is prepared through a simple hydrothermal and calcining method, efficient removal of
phosphorus in the
wastewater is achieved under the condition that the use amount is very small, the material can be recycled, the preparation cost is reduced to the maximumextent, and the adsorption performance is improved.