典型pH条件下水中离子对腐殖酸絮凝体构造的影响  

Effects of ion in water on humic acid floc structure under typical pH conditions

作　　者：冯永宁[1] 金鹏康[1] 王晓昌[1] 

机构地区：[1]西安建筑科技大学环境与市政工程学院,西安710055

出　　处：《环境化学》2013年第6期1088-1093,共6页Environmental Chemistry

基　　金：国家自然科学基金项目(50978211)资助

摘　　要：分析评价了几种典型化学条件对腐殖酸絮凝体构造的影响.研究结果表明,在pH=5.0低投药量下以共聚络合为主要混凝机理所形成的絮凝体结构密实,粒径分布均匀,强度大.而pH=5高投药量以及pH=7.0两种情况下的混凝机理都是以吸附和网扫絮凝为主,此时形成的絮凝体构造特征相似,尽管尺寸较大,但是结构松散,强度较小.针对水中常见的主量阴阳离子,分析探讨了典型离子对絮凝体构造特征的影响.研究表明,Cl-在腐殖酸水样中的存在对絮凝体构造基本没有影响,而SO24-和SiO23-在水样中的存在可使腐殖酸絮凝体尺寸增加0.05—0.13 mm左右,但结构比较开放松散,同时絮凝体的黏结力(即抗剪切力)大大削弱,降低了约0.018—0.047 N·m-2,并且SO24-对腐殖酸絮体构造的影响大于SiO23-对其的影响.然而,引入阳离子会对絮凝体的构造起到不同程度的改善作用.其中以Ca2+、Mg2+为代表的高价阳离子对絮凝体构造影响较大,形成的絮凝体结构密实,尺寸较大,抗剪切能力强.高价阳离子的存在会使絮凝体的粒径增加0.08—0.15 mm,抗剪切力增加0.002—0.013 N·m-2,而以K+、Na+为代表的低价阳离子对絮凝体构造的影响较小.The influence of several typical chemical conditions on the structure characteristics of humic acid flocs was evaluated in this paper.The results indicate that flocs formed by co-precipitation at pH 5 with low dosage had a compact structure,high strength and uniform particle distribution.Flocs formed by adsorption and sweep flocculation at pH 5 with high dosage and pH 7 showed similar structure characteristics,with a large size,loose structure and lower strength.The effect of typical ions on floc structure was also analyzed and discussed.The results show that Cl-had little effect on floc structure,whereas SO2-4 and SiO2-3 existing in humic acid water samples lead to increased flocs size by 0.05—0.13 mm and a looser structure.Moreover,the bonding force of flocs was greatly weakened,and reduce by about 0.018—0.047 N·m-2.The influence of SO2-4 on floc structure was greater than that of SiO2-3.However,dosing cations improvd floc structure to varying degrees.High valence cations such as Ca2＋,Mg2＋ had a notable effect on the floc structure.Flocs formed after dosing Ca2＋＋Mg2＋ were compact and large with a strong shearing resisting ability.They lead to increase of floc size and strength by 0.08—0.15mm and 0.002—0.013 N·m-2 respectively.The influence of low valence cations K＋ ＋Na＋ on floc structure was less.

关 键 词：典型化学条件 离子环境 絮凝体构造 絮凝体强度 

分 类 号：TU991.2[建筑科学—市政工程]