源于镀铝锌渣的复合铝锌铁混凝剂的制备及混凝特征

以镀铝锌渣(GAS)为原料,采用"混合酸浸及加碱聚合"两段法合成复合铝锌铁(PAZF)混凝剂,同时采用紫外可见分光光度计(UV)及扫描电镜(SEM)研究其制备过程的微观表现,然后与聚合氯化铝(PAC)对比研究其对染料废水的混凝特征。结果表明:酸浸及聚合的较佳时间分别为3和5 h;酸浸取物主要为锌、铝、铁的盐类及3种金属的硫酸氯化盐类;聚合形成了与金属盐类完全不同、具有不同吸收波长、种类较多的聚合类物质,且其结构随聚合时间的延长不断调整;随SEM放大倍数的增加,PAZF表面形貌发生很大变化,PAC基本无变化;放大4000倍时PAZF表现为一种表面积较大、较为匀称的褶皱式微观结构,放大8 000倍时呈现为较为匀称的网状菜花头式微观结构;PAZF应对水质变化的投药量范围宽于PAC,且去除浊度及有机物的最佳pH范围比较吻合,而PAC去除两者的最佳pH范围不同;PAZF具有的混凝特征取决于其独特的微观表现。

Preparation and coagulation behavior of poly-Al-Zn-Fe coagulant from galvanized-aluminum-slag

Poly-Al-Zn-Fe (PAZF) coagulant was prepared by a two-stage method of leaching with mixed acid and polymerizing with alkali using galvanized-aluminum-slag (GAS). Its micro-properties during preparation were conducted using UV-vis spectrophotometer (UV) and scanning electron microscopy (SEM). Coagulation behavior of PAZF was tested by Jar tests in treating a simulated dyeing wastewater compared with that of poly-aluminum-chloride (PAC). The results show that the optimal leaching time and polymerizing time are 3and 5hours, respectively. The acid leaching substances mainly contain zinc, aluminum and iron salts and polymers of these three metals of chloride-sulfate. Many types of polymeric substances with different absorption wavelengths were formed while their copolymer structures with characteristic absorption-peak of aluminum, zinc and iron were adjusted continuously with the increase of polymerizing time. The surface morphology of PAZF changed a lot at different magnification times, while PAC changed a little. PAZF appeared to have a kind of uniform pleated structure having larger surface area at 4000magnification times. However, it has a series of cauliflower head structure with some pleated ditch having different width and depth at magnification of 8000times. PAZF dosage range showing excellent coagulation efficiency in treating complicated qualities of water samples was wider than PAC. It had a consistent optimal pH range for removal of turbidity and organic matters compared with PAC showing different pH ranges. The distinctive coagulation behavior of PAZF was determined by its special micro-properties.