▎ 摘　　要

NOVELTY - A heavy metal ion adsorbent is prepared by mixing 5-10 pts. wt. graphene-iron(II,III) oxide-magnesium oxide-silica composite particles, 10-25 pts. wt. trisodium trithiocyanate, 5-15 pts. wt. hydroxide and 50-80 pts. wt. deionized water. The graphene-iron(II,III) oxide-magnesium oxide-silica composite particles comprise 5-10 pts. wt. graphene, 5-50 pts. wt. nano-iron oxide particles and 40-100 pts. wt. magnesium oxide-silica particles. USE - Adsorbent is used for adsorbing heavy metal e.g. nickel, lead, arsenic, mercury, manganese, cadmium and chromium, in heavy metal-containing wastewater (all claimed). ADVANTAGE - The adsorbent is disposed of by landfill, and is environmentally-friendly. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) graphene-iron(II,III) oxide-magnesium oxide-silica composite particles; (2) preparation of graphene-iron(II,III) oxide-magnesium oxide-silica composite particles, which involves adding an aqueous solution of nano-iron(II,III) oxide, an aqueous solution of magnesium salt, an aqueous solution of sodium silicate and an aqueous solution of graphene under stirring, heating, filtering reaction solution, drying the filter residue and grinding to a powder form; and (3) treatment of heavy metal-containing wastewater, which involves adjusting pH of wastewater to 2 or more, adding adsorbent in an amount of 15-25 g with respect to 1 L heavy metal-containing wastewater, stirring until the adsorption is complete, and removing the adsorbent.