▎ 摘　　要

NOVELTY - Metal adsorbent comprises: a polymer matrix comprising a polyamide; and silver-decorated graphene nano-platelets that are dispersed in the polymer matrix, where the polyamide comprises reacted units of an aromatic amine and an acyl halide. USE - The metal adsorbent is useful: in a filtration system; and for reducing a heavy metal content of a liquid (all claimed). ADVANTAGE - The metal adsorbent has a specific surface area of 200-300 m2/g, and an average pore size of 50-100 Angstrom (claimed). DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) a filtration system, comprising a vessel with an internal cavity, a liquid inlet and a liquid outlet, and the metal adsorbent disposed inside the internal cavity, where the filtration system is configured to adsorb at least a portion of at least one heavy metal from a liquid; (2) reducing (M1) a heavy metal content of a liquid, comprising contacting the liquid with the metal adsorbent to adsorb at least a portion of the heavy metal onto the metal adsorbent, where the heavy metals are at least one of mercury, chromium, cadmium, lead, nickel or copper or its cation; and (3) making (M2) the metal adsorbent, comprising mixing the silver-decorated graphene nano-platelets with the aromatic amine and water to form a suspension, separately dissolving the acyl halide in an organic solvent to form an acyl halide solution, and mixing the acyl halide solution with the suspension and heating to form the metal adsorbent.