Research And Apply On Poly-High-Ferric-Silicic Coagulant And Treatment Of Lead Wastewater

This paper studies the preparation of poly-high-ferric-silicic coagulant from fly ash extract , the performance and chemical properties of the new type coagulant through the experiments of treatment analog lead wastewater.It mainly includes aspects as follows:(1)The technology of preparing the poly-high-ferric-silicic by using fly ash extract has been designed.Through orthogonal experiment,the optimum extraction conditions from fly sah and the optimum technology of preparing the poly-high-ferric-silicic have been designed.Under 60℃, Leaching fly ash with NaOH when NaOH concentration of 1.8mol / L response to 38 hours to obtain fly ash extract. After filtration, the filtrate has been adjusted pH to around 1.4 and activated about 2.5 hours.Then by means of the polymerized reaction under 45℃and using potassium ferrate as complexing agent when Si/FeO42- is about 3.5,the poly-high-ferric-silicic can be obtained.(2)The chemical properties of poly-high-ferric-silicic.The comparison on index of coagulant between poly-high-ferric-silicic and poly-iron coagulant, the poly-high-ferric-silicic belongs to first-class product.The index of coagulant contains total fe, pH, density, polymeric level and basicity. The poly-high-ferric-silicic is the high performance coagulant in the absence of additional oxidant conditions. Under the optimum conditions, the poly-high-ferric-silicic natural storage time is up to 90 days. After adding magnesium chloride,the poly-high-ferric-silicic natural storage time is up to 240 days at least.(3)Coagulation properties of poly-high-ferric-silicic in treatment lead wastewater.The results showed that color, turbidity and Pb2+ removal efficiency are excellent and treatment effects are stable in treatment lead wastewater, especially the removal of Pb2+ has been up to 96% more. The comparison on coagulantion between poly-high-ferric-silicic and PPFS, the poly-high-ferric-silicic dosage is low and adapt to a wide pH. Therefore, by comparison, the poly-high-ferric-silicic is a superior coagulant in lead wastewater treatment.(4) The structure morphology of poly-high-ferric-silicic.Many modern analysis methods such as laser particle size analysis, transmission election microscopy and infrared spectrum have been applied to investigate those interactions among hydrolyzed ferric and the structure of poly-high-ferric-silicic.Then, discussing the mechanism of poly-high-ferric-silicic.The results shows that there are copolymer between high-iron group and activated silica in the polymerizing process. Poly-high-ferric-silicic is a sort of polymer with a state of branches structure.The Si/FeO42- value has remarkable effects on hydrolyzate of polysilicate and polyferric.There are two aspects about poly-high-ferric-silicic .On the one hand, relying on chargeneutrality of high-ferric hydrolysis products; on the other hand, relying on adsorption bridge of polymer between activated silicic acid and high-ferric. poly-high-ferric-silicic shows superior removal of turbidity color and Pb2+ by two aspects.(5)The research of poly-high-ferric-silicic reparation and treatment lead wastewater shows that it not only can get a good coagulation effect, but also save energy and play resources and technological advantages.This technology can produce important benefit on both environment and economy.