Preparation method and application of didodecyl gamma-biquaternary ammonium salt heterotrophic bacterium bactericide

The invention discloses a preparation method and application of didodecyl gamma-biquaternary ammonium salt heterotrophic bacterium bactericide. The preparation method comprises the following steps: firstly, adding a certain amount of dodecyl dimethyl tertiary amine, n-propanol and water into a reaction kettle, continuously stirring, heating to 50 DEG C, adding epoxy chloropropane to react for 3 hours at 50 DEG C, slowly dripping dodecyl dimethyl tertiary amine of which the amount is equal to that of dodecyl dimethyl tertiary amine used in the previous step, simultaneously dripping 10% hydrochloric acid to adjust the pH value of the reaction system to be within 8.0-9.0, heating to 60 DEG C after the materials are completely added, and stirring to react for 5 hours, thereby obtaining a heterotrophic bacterium bactericide (BDBAS) product disclosed by the invention, wherein the mole ratio of epoxy chloropropane to dodecyl dimethyl tertiary amine is 1.05:1. The BDBAS disclosed by the invention can be added into circulation water after being prepared into a solution with a certain mass concentration, when the content of BDBAS is 3-10g per cubic meter of circulation water, the removal rate of heterotrophic bacteria can be up to 92.99-99.47%.