▎ 摘　　要

NOVELTY - Preparing amino and pyrenyl group-modified alginic acid derivative (IV), comprises (1) acidifying sodium alginate, (2a) adding (II), N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine into beaker at room temperature, then adding deionized water, stirring to dissolve, adding ethylenediamine, and reacting at room temperature for 24 hours, and (2b) freeze-drying the solvent in the beaker of step (2a), then washing with dichloromethane and then with absolute ethanol, and drying in vacuum oven, and (3a) adding (III), 1-pyrenebutyric acid, N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine into 100 ml round bottom flask at room temperature, adding deionized water, and stirring at room temperature for 48 hours, and (3b) filtering the solution obtained in step (3a), washing the filter cake with tetrahydrofuran, then washing twice with absolute ethanol, and drying in vacuum oven to obtain final product. USE - The amino and pyrenyl group-modified alginic acid derivative is useful in alginic acid derivative ammonium salt/graphene composite material for formaldehyde absorption (all claimed), and purifying air and water polluted by aldehydes. ADVANTAGE - The alginic acid derivative ammonium salt/graphene composite material is composed of modified alginic acid derivative: realizes the chemical removal of formaldehyde and other aldehydes under the conditions of normal temperature and pressure without catalyst; produces water as by-product; and can combine with the huge specific surface area of the graphene carrier to specifically, and irreversibly absorb harmful substances including formaldehyde. DETAILED DESCRIPTION - Preparing amino and pyrenyl group-modified alginic acid derivative of formula (IV), comprises (1) acidifying sodium alginate to obtain alginic acid of formula (II), (2a) adding (II), N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine into beaker at room temperature, then adding deionized water, stirring to dissolve, adding ethylenediamine, and reacting at room temperature for 24 hours, and (2b) freeze-drying the solvent in the beaker of step (2a), then washing with dichloromethane and then with absolute ethanol, and drying in vacuum oven at 40 ℃ for overnight to obtain an amino-containing alginic acid derivative of formula (III), where in step (2a), the dosage ratio between (II), N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine, deionized water and ethylenediamine is 2.2-4.4:2.98-4.96:0.35-0.7:60-120:6.6-13.2 (g:g:g:ml:ml), and (3a) adding (III), 1-pyrenebutyric acid, N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine into 100 ml round bottom flask at room temperature, adding deionized water, and stirring at room temperature for 48 hours, and (3b) filtering the solution obtained in step (3a), washing the filter cake with tetrahydrofuran, then washing twice with absolute ethanol, and drying at 45 ℃ for overnight in vacuum oven to obtain final product; where in step (3a), the consumption ratio between (III), 1-pyrenebutyric acid, N,N'-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and deionized water is 0.5-1:0.1-0.2:0.83-1.66:0.1-0.2:25-50 (g:g:g:g:ml). INDEPENDENT CLAIMS are also included for: amino and pyrenyl group-modified alginic acid derivative prepared by above method; preparing alginic acid derivative ammonium salt/graphene composite material, comprising (Aa) taking (IV) in beaker, adding deionized water and triethylamine, and sonicating until dissolve, (Ab) taking graphene oxide, adding into deionized water, and ultrasonicating for 5 minutes, (Ac) slowly adding the solution obtained in step (Aa) into the solution obtained in step (Ab) with volume ratio of 1:5 to obtain a mixed solution, adding L(+)-ascorbic acid into the mixed solution with the dosage ratio of 60:1 (ml:g), and stirring at 80 ℃ for 20 hours, and (Ad) filtering the solution obtained in step (Ac), washing the filter cake with deionized water, and drying in vacuum oven at 60 ℃ for overnight to obtain alginic acid derivative/graphene composite material, and (Ba) adding the alginic acid derivative/graphene composite material into buffer solution with the amount of 0.2-0.5:50-100 (g:ml) and stirring for 1 hour, and (Bb) filtering the solution obtained in step (Ba), washing the filter cake with deionized water, and drying in vacuum oven at 60 ℃ for overnight to obtain alginic acid derivative ammonium salt/graphene composite material; and alginic acid derivative ammonium salt/graphene composite material prepared by above method. n = 80-750. Provided that: x+y = n, and x/y = 1/10.