▎ 摘　　要

NOVELTY - Sewage treatment hydrogel comprises 5-90 pts. wt. polyethylene alcohol, 5-90 pts. wt. chitosan, 0-20 pts. wt. sodium carboxymethyl cellulose, 0.05-0.3 pts. wt. graphene oxide and 3-5 pts. wt. sodium alginate. USE - The hydrogel is useful for absorbing heavy metal ions in water. ADVANTAGE - The hydrogel: has high heavy metal ion absorbing capacity and high selectivity; ensures recycling of heavy metal ion containing water; and is biodegradable. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the hydrogel, comprising (a) preparing graphene oxide aqueous solution, (b) introducing polyethylene alcohol, sodium alginate and sodium carboxymethyl cellulose, and deionized water into a three-necked bottle, boiling under water bath, and stirring uniformly to obtain mixed solution, (c) heating the mixed liquid in a water bath at 60-100 degrees C, simultaneously, adding chitosan, stirring for 2-10 hours to uniformly mix, (d) cooling to room temperature, adding graphene oxide aqueous solution, ultrasonically processing for 0.2-2 hours, stirring for 0.2-2 hours to uniformly disperse graphene oxide, (e) adding 3% calcium chloride-boric acid saturated solution into the resulting solution using a dropper, carrying out chemical crosslinking to prepare spherical granular hydrogel having particle diameter of 0.5-5 mm, soaking and rinsing the particles in deionized water for 12-36 hours.