Cationic heavy metal trapping agent as well as preparation method and application thereof

The invention relates to the technical field of wastewater treatment, and discloses a cationic heavy metal trapping agent as well as a preparation method and application thereof. The cationic heavy metal trapping agent is prepared from the following raw materials: an alcohol amine compound, methane halide and carbon disulfide, the mass ratio of the alcohol amine compound to the methane halide to the carbon disulfide is 10: (4-8): (7-9). In the cationic heavy metal trapping agent taking the alcohol amine compound, the methane halide and the carbon disulfide as main raw materials, sulfydryl groups can be chelated and coordinated with heavy metal ions in wastewater to form precipitates, and the methane halide and the alcohol amine compound are subjected to substitution reaction to form a quaternary ammonium salt cation structure; and the heavy metal particles can generate an electric neutralization effect with colloid particles with negative electricity in the wastewater, so that heavy metal floc particles are d