| It is very important of the researches on exploiting the resources by reusing the industrial wastes.Through lots of tests, the new technology of preparing the polymeric ferric aluminum silicate sulfate (PFASS) by using the waste-acid of Ti02-industriy and the coal fly ash has been designed. The highest Al-acid stripping rate can be achieved by the waste sulfate acid under boiling degree for 1. 5h when the mass ratio between NaCl and Coal Fly ash is 0. 05:1, as well as that between Coal Fly ash and Waste Acid ratio is 1:10. By means of the oxidation-polymerized reaction under 40-50*C and normal pressure, using NaNCkas catalyst and air as oxidation, the polymeric ferric aluminum sulfate can be obtained. The poly-silicic acid is polymerized with soluble glass in the optimum conditions of pH=5-6 and the concentration of Si02 is about 3%. The inorganic high molecule coagulant of PFASS is synthesized with the poly-silicic acid into the solution of polymeric ferric aluminum sulfate. The adjust accounts on economics show that this technology can produce important benefit on both environment and economy.The treatment of landfill leachate by flocculation has been tested. The effects of different (Fe+Al)/Si molar ratio, basicities(B), the consumption of PFASS and the pH of the leachate are investigated. The flocculation results show as a special complex flocculation for treating landfill leachate, the optimal technical indexes of PFASS are as follows: the (Fe+Al)/Si molar ratio is 2:1, B should not be adjusted by titration and the aging time is 2d. When the agent consumption is 60ml/L, the best flocculating efficiency can be achieved, the removal efficiency of color, turbidity, SS and CODcr is 88.2%, 94.0%, 95% and 91.6% respectively. Compared to PFS and PAC, PFASS has obvious superiority. By adding an appropriate amount of the coal fly ash to PFASS, the coal fly ash-based coagulant combining both physical adsorption and chemical flocculation capabilities has been obtained. The complex coagulant has a higher rateof settlement, a smaller volume of sludge, a lower cost of treatment and a higher removing rate of CODCr and SS than that of simple PFASS. In this essay, the mechanism of chemical flocculation of PFASS coagulant is analyzed, as well as the physical adsorption of the coal fly ash.Many modern analysis methods such as the base titration and continuous acid reverse titration experiments, the infrared spectrum, the X-ray diffraction and the transmission electron microscope have been applied to investigate those interactions among hydrolyzed ferric and aluminum species and poly-silicic acid and the structure of PFASS. The results show that there are interactions between hydrolyzed ferric and aluminum in the polymerizing process and PFASS is a sort of amorphous polymer with a state of branches stretching to the three dimensions space. The molecule chains close to a cage type. The n(Fe+Al)/n(Si) value has remarkable effects on species and the distribution of copolymers. With the increase of the molar ration of Si, PFASS show a lattice chain structure. |
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