▎ 摘　　要

NOVELTY - Preparation of composite flocculant comprises preparing graphene oxide by slowly adding sulfuric acid to flask, adding graphite and sodium nitrate, adding potassium permanganate, water and hydrogen peroxide, centrifuging, and washing with hydrochloric acid and water; washing attapulgite with water, centrifuging, mixing water, mixing attapulgite and hydrochloric acid, , filtering, washing with water, and drying; and weighing chitosan and modified attapulgite, adding acetic acid, dispersing zinc oxide particles and graphene oxide, adding glutaraldehyde, crosslinking, and heating. USE - Method for preparing composite flocculant used for removing metal ions and organic dyes (claimed). ADVANTAGE - The method does not need special equipment, reduces dosage of chitosan, and reduces cost. The flocculant can remove organic pollutant, nickel, heavy metal ion including chromium and lead, methylene blue and organic dyes in water. It has more than 90% adsorption removal rate of low concentration heavy metal ion in waste water, and 92& removal rate of methylene blue. DETAILED DESCRIPTION - Preparation of composite flocculant comprising: (A) preparing graphene oxide by slowly adding 200-250mL concentrated sulfuric acid to 1 L three-necked flask, adding 10-15 g graphite and 3-5 g sodium nitrate in sequence, grinding, stirring for 1-1.5 hours, slowly adding 25-35 g potassium permanganate, mechanically stirring in ice-water bath for 1.5-2 hours, heating to 30-40 degrees C for 2-2.5 hours, slowly adding 200-250 ml deionized water at 30-40 degrees C, heating to 80-90 degrees C, stirring for 10-20 minutes, slowly adding 400-500 mL deionized water, stirring for 2 minutes, adding 20-25 mL hydrogen peroxide to terminate reaction, stirring for 10-20 minutes, centrifuging, and washing repeatedly with dilute hydrochloric acid and deionized water until pH of 7; (B) weighing 10-20 g 300-1000 mesh attapulgite, washing with 1 L distilled water, taking supernatant, centrifuging at 500 revolutions/minute for 1 minute, mixing supernatant with distilled water, centrifuging at 500 revolutions/minute for 1 minute, taking supernatant, repeatedly washing supernatant for 3-5 times, centrifuging at 4000 revolutions/minute, taking precipitates, vacuum drying at 90 degrees C for 24 hours, grinding, sieving, purifying, disposing hydrochloric acid solution with concentration of 0.5-3 mol/L, taking 10-20 g purified attapulgite and 150-200 mL hydrochloric acid solution into small beaker, mixing for 5 minutes, heating mixture to 70-80 degrees C, stirring for 1-2 hours, sonicating for 30-40 minutes, suction filtering, washing with distilled water to pH of 6, vacuum drying at 60 degrees C for 24 hours, and sieving; and (C) weighing 4 g chitosan and modified attapulgite at mass ratio of 4:1-5:1, adding 100 ml 1-2% acetic acid solution, stirring, dispersing 20-300 nm zinc oxide particles and graphene oxide, grinding, sonicating for 2 hours, using 1 mol/L sodium hydroxide solution to adjust pH to 10, adding 20-30 ml glutaraldehyde, crosslinking for 3-5 hours, stirring at 60 degrees C in water bath, suction filtering crosslinked flocculant, washing with distilled water until neutral, and vacuum heating at 50-70 degrees C.