Nano-TiO2回收过程中SO42-对不同混凝剂混凝过程的影响

为了降低纳米TiO₂使用成本，采用不同混凝剂对纳米TiO₂悬浊液进行固液分离.通过考察浊度去除率、出水pH值的变化情况，并结合X射线光电子能谱（XPS）、傅里叶红外光谱（FTIR）、固体核磁（NMR）、扫描电镜（SEM）及能谱分析（EDS）表征，探究了纳米TiO₂回收过程中SO₄^2-对不同混凝剂混凝过程的影响.结果表明，当使用AlCl₃作混凝剂时（0.1mmol/L），SO₄^2-浓度从0.0mmol/L增加到20.0mmol/L，浊度去除率降低了0.80%，絮体粒径从450μm下降到215 μm，而强度因子无明显变化.低聚合态的Al_a不与SO₄^2-结合，混凝过程中通过吸附架桥和网捕卷扫的作用形成大量无定形的Al （OH）₃.当使用Al₁₃作混凝剂时，再生长后絮体的粒径随着SO₄^2-浓度的增加而下降，S-O峰的红移证明有新的含S聚合物产生，Al 2p的峰均向较高的结合能移动证明生成的絮体不是Al （OH）₃.

Effect of SO42- on coagulation performance using different coagulants in nano-TiO2 recovery process

In order to reduce the practical cost of nano-TiO₂, the TiO₂ was isolated via solid-liquid process by applying different coagulants. By investigating the turbidity removal rate, effluent pH value, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), solid state nuclear magnetism (NMR), scanning electron microscopy (SEM), and energy spectrum analysis (EDS), the effects of SO₄^2- on the coagulation efficiency during nano-TiO₂ recycling process was studied. The results showed that the turbidity removal rate decreased by 0.80%, and the floc size decreased from 450μm to 215μm when the concentration of SO₄^2-increased from 0.0mmol/L to 20.0mmol/L under AlCl₃ (0.1mmol/L), while the strength factor of flocs did not change significantly. The low polymerization species Al_a could not react with SO₄^2-, and generated large amount of amorphous Al(OH)₃ via adsorption bridging and flocculation sweeping effects during coagulation process. When Al₁₃ was used as coagulant, the size of re-growth flocs decreased with the increasing of SO₄^2- concentration. The occurrence of red shift for S-O peak indicated that the new S-containing polymers were produced. The movement of Al 2p peak toward higher binding energy revealed that no Al(OH)₃ was generated in the flocs.