▎ 摘　　要

NOVELTY - Preparing chitosan-based graphene/titanium dioxide composite microspheres involves: (1) adding tetrabutyl titanate to absolute ethanol, evenly mixing, then dripping into ethanol solution of small molecular organic acid, ultrasonically dispersing, adding graphene oxide, oscillating, ultrasonically dispersing, adding deionized water, oscillating, sealing, and ultrasonically dispersing to obtain graphene/titanium dioxide gel; (2) preparing titanium dioxide/graphene composite; (3) preparing a chitosan sol; (4) adding the graphene/titanium dioxide composite to the chitosan sol, ultrasonically processing, stirring to obtain chitosan-based graphene/titanium dioxide composite sol, then dripping into sodium hydroxide solution, leaving still to obtain microspheres; and (5) placing the microspheres in methanol solution containing glutaraldehyde, continuously stirring, filtering, removing solid, washing 2-3 times with absolute ethanol and deionized water, and vacuum drying at 50-60 degrees C. USE - The method is useful for preparing chitosan-based graphene/titanium dioxide composite microspheres (claimed) for degrading organic wastewater and catalytic degradation of adsorbed polymer organic pollutants. ADVANTAGE - The method provides chitosan-based graphene/titanium dioxide composite microspheres with high adsorption treatment efficiency and catalytic degradation ability, and excellent strength. DETAILED DESCRIPTION - Preparing chitosan-based graphene/titanium dioxide composite microspheres involves: (1) adding tetrabutyl titanate to absolute ethanol, evenly mixing, then dripping into ethanol solution of small molecular organic acid at a rate of 2-3 drops/second, ultrasonically dispersing at 400-600 W for 5-10 minutes, adding graphene oxide, evenly oscillating, continuously carrying out ultrasonic dispersion for 20 minutes, slowly adding deionized water under ultrasonic wave at a speed of 1 ml/minute, evenly oscillating, sealing, and ultrasonically dispersing for 0.5 hour to obtain graphene/titanium dioxide gel; (2) drying the gel under vacuum at 40-60 degrees C, grinding into powder, and baking under nitrogen protection at 450 degrees C for 2.5-3.5 hours to obtain titanium dioxide/graphene composite; (3) dissolving polyvinyl alcohol in deionized water at 80-90 degrees C and 600-1000 rpm for 10-20 minutes to prepare 8-12 g/l solution (A), stirring and dissolving chitosan in 2 vol.% aqueous solution of glacial acetic acid to prepare 20-30 g/l solution (B), dripping the solution (A) into the solution (B), stirring at room temperature and 600-1000 rpm for 6-12 hours, and leaving still for 24 hours to prepare a chitosan sol; (4) adding the graphene/titanium dioxide composite to the chitosan sol, ultrasonically processing for 10-20 minutes, stirring at room temperature and 600-1000 rpm for 4-8 hours to obtain chitosan-based graphene/titanium dioxide composite sol, then dripping the composite sol into a 3 g/l sodium hydroxide solution, and leaving still for 24 hours to obtain 1-4 mm microspheres; and (5) placing the microspheres in 1.25-2.5 vol.% methanol solution containing glutaraldehyde, continuously stirring at 600-1000 rpm for 4-5 hours, filtering, removing solid, washing 2-3 times with absolute ethanol and deionized water, and vacuum drying at 50-60 degrees C. The volume-to-mass ratio of glutaraldehyde to chitosan is (0.5-0.8) ml:1 g. The volume ratio of tetrabutyl titanate to absolute ethanol is 1:(4-10). The mass-to-volume ratio of small molecular organic acid to tetrabutyl titanate is (0.5-1) g:1 ml. The mass-to-volume ratio of graphene oxide to tetrabutyl titanate is (0.1-0.2) g:1 ml. The concentration of the ethanol solution of small molecular organic acid is 0.1-0.2 g/ml. The usage amount of deionized water is 1/6-1/3 of the amount of absolute ethanol. The mass ratio of polyvinyl alcohol to chitosan is (0.5-2):10. The mass ratio of the graphene/titanium dioxide composite to chitosan is (4-8):100.