Didodecyl γ-biquaternary ammonium salt (DBAS)was synthesized from industrial di-methyl-dodecylamine and epoxy chloropropane in pilot scale.The yield was up to 96.08%.1 H NMR spectra showed that it has the groups which were the same as laboratory production,such as———N +(CH3 )2—,—OH,and so on.The DBAS synthesized in pilot scale were applied in the circulating cooling water of a coking plant in Shandong.The results show that DBAS has an obvious inhibitory effect on het-erotrophic bacteria in circulating cooling water system,when 10 L DBAS (5.7%)was added to circulat-ing cooling water which has a capacity volume of 900 m3 ,the sterilization efficiency can be up to 96.08%in 2.5 h,and the efficiency can remain 93.64% in 2 d,it has larger antibacterial performance improve-ment compared with the original oxidizing biocide.DBAS has an obvious inhibitory effect on heterotrophic bacteria in circulating water system,the relation between dosage and turbidity were positively correlated, so 5 L 5.7% DBAS was added into the circulating cooling water system every 3 d,the water quality indi-cators can meet the plant’s inspection standard (≤20NTU)during the almost-one-month trial (below 6NTU).DBAS has a quick efficacy which can last for a long time,and it can make bacteria separate from circulating water easily,so it can be widely used to kill heterotrophic bacteria in industrial circulating cooling water system,it’s a new ideal industrial biocide,and it has certain market application prospect and promotional value.%在小试的基础上，以工业级十二烷基二甲基叔胺和环氧氯丙烷为原料，于50 L 反应釜中合成了一种对称型阳离子双十二烷基γ-双季铵盐杀生剂（DBAS），收率高达96．08％，1 H NMR 图谱表明其分子中含有—N ＋（CH3）2—和—OH 等基团，与小试产物结构相同。以山东某焦化厂的循环冷却水为对象，DBAS 为杀生剂进行现场试用。结果表明，向保有水量为900 m3的循环冷却水系统中投加10 L 5．7％ DBAS 溶液，2．5 h 内杀菌率即达96．08％，加药2 d 后，杀菌率仍为93．64％，较原氧化性杀生剂有较大抑菌性能提升。DBAS 对循环水系统中异养菌具有明显抑制作用，其投加量与浊度变化关系呈正相关关系，据此确立以其为指示的杀生机制及投加周期，即每3～5 d 投加1次，每次投加5 L 浓度为5．7％的 DBAS。为期一个月的现场试用，其循环水浊度均低于6NTU，远低于该公司要求≤20NTU 的考核指标。双季铵盐杀生剂 DBAS 具有杀菌见效快、药效持续时间长、菌体易从循环水系统中分离等优点，适用于工业循环冷却水中微生物控制，是一种较理想的新一代工业用杀生剂，有一定的市场应用前景和推广价值。
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