稀释和熟化对钛盐絮凝效果及混凝机制的影响

Influences of Dilution and Aging on Flocculation Effects and Coagulation Mechanism of Titanium Salts

为了明晰工艺条件对钛盐混凝剂去除水中污染物的作用效果,主要研究稀释和熟化对钛盐絮凝效果的影响,结合Zeta电位的变化,探讨钛盐的混凝机制。结果表明:熟化能使氯化钛和硫酸钛水解生成优势絮凝形态,促进其絮凝效能的发挥;聚合氯化钛和聚合硫酸钛发挥絮凝作用的水解产物在加入废水前已经形成,聚合氯化钛受熟化影响较小,熟化使聚合硫酸钛絮凝形态发生改变,导致絮凝效果劣化;钛盐水解快的特点导致絮凝效果受到稀释的影响,促进氯化钛的优势絮凝形态生成,提高絮凝能力,但造成聚合氯化钛对有机物去除率下降;当以钛离子质量浓度计的钛盐混凝剂投加量为5~30 mg/L时,氯化钛和硫酸钛的混凝机制以吸附电中和为主,聚合氯化钛和聚合硫酸钛的混凝机制以网捕卷扫为主。

To clarify the effects of process conditions on removal of pollutants in water by titanium salt coagulant,influences of dilution and aging on flocculation effects of titanium salts were researched.Combined with changes of Zeta potential,coagulation mechanisms of titanium salts were discussed.The results show that aging can hydrolyze titanium chloride and titanium sulfate to form dominant flocculation morphologies and promote their flocculation efficiency.Hydrolysates of polymeric titanium chloride and polymeric titanium sulfate which play a role in flocculation are formed before being added into wastewater.Polymeric titanium chloride is less influenced by aging,and the flocculation morphology of polymeric titanium sulfate changes due to aging,resulting in flocculation effect degradation.The characteristic of fast hydrolysis of titanium salts leads to influences of dilution on flocculation effects,which promotes the formation of dominant flocculation morphology of titanium chloride and improves the flocculation capacity,but results in decrease of removal rate of organic matters due to polymeric titanium chloride.When the dosage of titanium salt coagulant is 5-30 mg/L based on the mass concentration of titanium ion,the coagulation mechanism of titanium chloride and titanium sulfate is mainly adsorption and electric neutralization,and the coagulation mechanism of polymeric titanium chloride and polymeric titanium sulfate is mainly net and sweep.