| The method of flocculation is the one of the most important technology controlling water pollution. Flocculants are the critical part and the core basis of the technology.At present,flocculants based on salt aluminium are chiefly used abroad and at home. Because the flocculant based on the aluminium salt is low efficiency and exists environment problems, in our country and all over the world, the research and application of flocculant are required to be innovated and raised. At present, the trench of development on the research of flocculant are chiefly :the high efficiency, low consumption, safety, no harmlessness and no two-time pollution. The research of iron system flocculate belongs to the forward position of flocculation science. In this paper, the by-product of titanium white manufacture, FeSO4·7H2O, is used as the raw materials to study the preparation of composite flocculant based on polyferric. A lot of explorations and efforts are made to study and apply high efficiency composite flocculant based on the polyferric in this paper.The major contents of research have: the research of inorganic composite flocculant polyferric silicate sulfate (PFSiS) based on the polyferric and cationic starch-modified inorganic-organic composite flocculant(PFS-CSM) based on the polyferric. They all include the research of preparation,flocculating action mechanism, flocculating effect and water treatment application trial etc.In this paper, the major contents of preparing PFSiS are as follows: Firstly,the waste residue of titanium white manufacture ,FeSO4·7H2O, is served as the raw material to synthesize inorganic high molecular flocculant polyferric sulfate. Secondly, water glass is used to produce the activated poly silicic acid polymer.Finally,polyferric sulfate and activated poly silicic acid are compounded to make the new type of inorganic high molecular composite flocculant PFSiS. The research result is shown that the percentge of SiO2 is between 1.4~2.0%, the mol ratio of iron to silicon is between 0.8~1.2, the pH value of PFSiS is 1.5~1.8, the activated time of silicic acid is between 1~18 hours, the flocculant has excellent flocculation and better stability. PFSiS, that contains no pollutant of environment ,has huge molecular weight and uses the by-product of industry as the raw material, has the following merits: one is safety,no harmlessness,no two-time pollution. The others are that it has high efficiency and low consumption；and it can partly replace the organic synthesis high polymer flocculatethat price is expensive and has toxicity. Another is that the cost is very cheap, and the additional value is very high.For the first time, micro-electrophoresis technology is used to explore the flocculating mechanism of PFSiS, reveal the superiority form of flocculating action and provide the science basis for developing the flocculant.The pH change laws of PFS, PSi and PFSiS are investigated. It is found that the pH value of PFSiS will change with aging time. The results show that there is interaction between PFS and PSi, and the pH value may affect the degree of their interaction. The results also show that their reaction is not in equilibrium when the flocculant is newly prepared. In acid condition, the pH value changes smoothly when the prime pH is 1.46. But when the prime pH value is higher (1.70) or lower (0.64), the pH value of PFSiS shows apparent relaxation change. The results show that the species of PFSiS will change when the prime pH value is higher or lower. Otherwise, the Fe/Si molar ratio can affect the pH relaxation of PFSiS. When Fe/Si is higher, the pH relaxation of PFSiS changes as PFS does; and when Fe/Si is lower, the pH relaxation of PFSiS changes as PSi does.The ultraviole-visible spectrometric determination shows that, polysilicate (PSi) almost has not abvious absorbence in the range of 200～1000nm wavelength; the absorption spectrometric of PFSiS and PFS is different in the range of 200～400nm wavelength. In acid condition, when the pH value rises, because the a...
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