Patent ID: 8721763

Claim:
A method for separating metal nanoparticles from colloidal metal solution, comprising: providing a colloidal metal solution, including a plurality of metal nanoparticles; mixing a precipitating agent with the colloidal metal solution for maintaining a pH of the colloidal metal solution in a specific value; keeping the colloidal metal solution stationary with no external forces applied for a static time at an environmental temperature, such that the metal nanoparticles precipitate from the colloidal metal solution, and the colloidal metal solution forms a supernatant and a precipitating liquid; separating a precipitate from the precipitating liquid by a filtering process; and liquid sprinkling the precipitate by a first solvent to obtain the metal nanoparticles, wherein the precipitating agent is a third solvent including a compound, and the compound is dissolved in the third solvent and is selected from the group consisting of methylamine (CH 3 NH 2 ), ethylamine (CH 3 CH 2 NH 2 ), aminoethanol (H 2 N(CH 2 ) 2 OH), ethylenediamine (C 2 H 4 (NH 2 ) 2 ), dimethylamine ((CH 3 ) 2 NH), trimethylamine (N(CH 3 ) 3 ) triethylamine ((C 2 H 5 ) 3 N), propylamine (C 3 H 7 NH 7 ), isopropylamine, (i-C 3 H 7 NH 2 ), 1,3-propylenediamine (NH 2 (CH 2 ) 3 NH 2 ), 1,2-propylenediamine (CH 3 CH(NH 2 CH 2 NH 2 )), tripropylamine ((CH 3 CH 2 CH 2 ) 3 N), triethanolamine ((HOCH 2 CH 2 ) 3 N), butylamine (C 4 H 9 NH 2 ), isobutylamine (C 4 H 9 NH 2 ), tert-butylamine (C 4 H 9 NH 2 ), n-hexylamine (H(CH 2 ) 6 NH 2 ), n-Octylamine (H(CH 2 ) 8 NH 2 ), benzeneamine (C 6 H 5 NH 2 ), benzylamine (C 7 H 9 N), pyridine (C 5 H 5 N), polyacrylamide ([—C 3 H 5 NO—] n ), polyacrylic acid ([—C 3 H 4 O 2 —] n ), sodium polyacrylate ([—CH 2 —CH(COONa)-] n ), and combinations thereof.