The invention discloses a method for synthesizing gemini
long chain alkyl quaternary ammonium salts by enabling
long chain alkyl tertiary amine mixture to be reacted with dibromo
hydrocarbon or
epoxy chloropropane and an application as a drag reduction and
energy conservation agent of a circulating water
system. The method comprises the following steps: stirring and dissolving the
long chain alkyl tertiary amine mixture in an
organic solvent, and heating to
reflux temperature; slowly adding dibromoethane or
epoxy chloropropane for generating mixture of asymmetric and symmetric gemini long chain alkyl
quaternary ammonium salts; stopping the reaction when the
tertiary amine conversion rate is above 75%, and performing
vacuum evaporation for recovering the
solvent; and using deionized water to dissolve
distillation products, and oxidizing the non-converted
raw material to
tertiary amine oxide with
hydrogen peroxide at the temperature of 60-80 DEG C. A gemini
quaternary ammonium salt surfactant is used as main molecules of the drag reduction agent, an
organic acid corrosion inhibitor is used as auxiliary ions, the
molar ratio of the main molecules to the auxiliary ions is 1: (2.4-6.0), then the drag reduction agent which is applicable to the range of 5-95 DEG C is prepared, and the drag reduction efficiency of the drag reduction agent to the circulating water
system achieves 40%-70%, and the
corrosion inhibition efficiency achieves 60%-95%. By adopting the gemini long chain alkyl quaternary ammonium salt surfactant, the problems of strong
corrosion, great
irritation and a
narrow range of applicable temperature of the traditional long chain alkyl quaternary ammonium salt surfactant can be overcome.