▎ 摘　　要

NOVELTY - Core-shell particles comprises core portion and a shell portion covering the core portion, core moiety comprises a polymer and nanoparticles dispersed in the polymer, shell portion contains a hydrophilic polymer. USE - Core-shell particles used in the separation and recovery of carboxyl group-containing polymers and their salts in enhanced oil recovery wastewater (Claimed). ADVANTAGE - Preparation method has simple process and realize batch production, and prepared core-shell particles have strict chemical partition and have magnetism, so the process of separating and recovering the polymer containing carboxyl and the salt thereof in the liquid by utilizing the core-shell particles is simple, and the cyclic recycling is realized. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) Preparation method of the core-shell particle, which involves: i. mixing oil-soluble monomers, cross-linking agents, oil-soluble initiators and nanoparticles as oil phase; and ii. dissolving surfactant in water as the water phase; mixing oil-water two phases, and the emulsion polymerization is carried out after emulsification; iii. after the emulsion polymerization reaction is completed, adding the hydrophilic monomer and the hydrophilic initiator, and the carrying out polymerization of the hydrophilic monomer. (2) Method for separating and recovering the polymer and its salt containing carboxyl group in the liquid, which involves: i. dispersing core-shell particles with water to obtain a dispersion of core-shell particles; ii. mixing the obtained dispersion with the liquid, and stirring the mixed liquid to realize the adsorption of the polymer in the liquid; iii. inserting a magnetic rod into the mixed solution, and separate and recover core-shell particles by the magnetic rod; iv. removing the magnet bar.