纳米SiO_2对微污染物HA、SDS及NH_3-N的助凝特性研究

Study on flocculation aid characteristics of silica dioxide nano-particles to micro-pollutants HA,SDS and NH_3-N

以聚合氯化铝PAC为混凝剂,纳米SiO2为助凝剂,对含有下列微污染物:十二烷基硫酸钠(SDS)、氨氮(NH3-N)或腐植酸(HA)的高岭土悬浊液进行混凝沉降实验。借助形态学理论、电镜观察与图像分析技术,研究纳米SiO2对微污染物的助凝作用效果、吸附特性与絮体结构的形态学特征。结果表明:(1)在含有HA、SDS、NH3-N的模拟原水中,污染物去除率与浊度去除率的相关性随污染物分子量的增大而增强;(2)纳米SiO2对HA、SDS及NH3-N的助凝吸附效果,随分子量的降低而减弱。纳米SiO2能促使PAC对HA、SDS与NH3-N的去除率分别提高40%～50%、20%～30%和10%～15%;(3)纳米SiO2能促使PAC作用下的絮体粒径增大、密实度和分维值增加、沉速加快。

For kaolin suspension containing dissolved low concentration micro-pollutants-sodium dodecyl sulfate （SDS） , ammonia nitrogen （ NH3-N） , and humic acid （HA） , coagulation experiments and quiescent settling experiments were done by adding polyalu minium chloride （PAC） and a new water treatment chemical-silica dioxide nano-particles respectively. The flocculation aid mechanism and action efficiencies, adsorption properties and morphological characteristics of flocs fractal structures were investigated by using morphological theory, electron microscopic observation and image analysis technology. The results showed that the removal rate correlation between micro-pollutants and turbidity enhances with molecular weight increment in simulating raw water containing HA, SDS or NH3-N. Adsorption efficiencies of the flocculant aid-silica dioxide nano-particles to micro-pollutant （HA, SDS or NH3-N ） reduced with the decrease of molecular weight. The flocculant aid-silica dioxide nano-particles could improve the removal rate of PAC to HA, SDS or NH3-N by 40%-50% , 20% - 30% or 10% - 15% , respectively. The floes had a bigger size in suspension and an increased effective mass density and settling velocity, and the value of fractal dimension increased.