Study On The Preparation,species And Coagulation Performance Of Polymeric Phosphate Ferric Sulfate Flocculants

In this experiment, The preparation of the Polymeric Phosphate Ferric Sulfate Flocculants was that PFS solution that have been prepared by introduced in PO₄^3-. the efficiency and the stability of PPFS could markedly improve, since PO₄^3- insert a network structure of molecular clusters of PFS to increase the bridging role.The optimum preparation conditions of poly-ferric silicate sulfate were determined by using the effect of a single disturbance method in this experiment. The flocculants would have preferable stability and the optimum effect of flocculantion if were prepared while PO₄^3-/Fe mole ratio was 0.3, polymeric temperature was 80°C, polymeric time was 60 minutes and a alkalization degree is 0.2; By means of orthogonal design, the interinfluences among all the factors were studied.The experiment showed: of all the factors, the effect of flocculantion were mainly affected by the PO₄^3-/Fe mole ratio .The hydrolysis of the inorganic coagulant was colloids in the process of flocculation,then the colloids can remove pollutants in water by the bridge-aggregation ability,adsorption,charge-neutralisation capacity. The coagulation efficiency correlate with the irron species in the solution.Polymeric Phosphate Ferric Sulfate flocculants prepared had a good characterization of efficiency and the stability quality; So the iron species of Polymeric Phosphate Ferric Sulfate flocculants were studied .In this experiment , the methods used to study the iron species include Fe-Ferron complexation timed spectrophotometry,ultraviolet spectrophotometric method,FT-infra red spectroscopy method (FTIR) and X-ray diffraction(XRD).Fe-Ferron complexation timed spectrophotometry studied showed that the amount of Fec in Polymeric Phosphate Ferric Sulfate flocculants was most, while the amount of Fea and Feb were small. As the aging time increased , the amount of Feb and Fea would decrease, while the amount of Fec would increase; But these three species in Polymeric Phosphate Ferric Sulfate flocculants did not change when the aging time was 5 days .Ultraviolet spectrophotometric method studied showed: the iron species in Polymeric Phosphate Ferric Sulfate flocculants were very complex; The absorption peak of flocculants under different preparation conditions had little difference at the rang of wavelength from 200～400nm, but only had some differences at the rang of wavelength from 400～500nm . Infared spectrum method studied showed that The absorption peak of Polymeric Phosphate Ferric Sulfate flocculants had markedly difference at the rang of wavelength from 900～1200cm-1. it's probable the vibrations of Fe-OH-Fe or Fe-PO₄ generated these peaks. This suggested that complex reaction between the hydrolysis of chelated iron and phosphate ions produced Fe-PO₄. So a new type of inorganic polymer flocculants of PPFS different from PFS was prepared.X-ray diffraction method studied showed:Polymeric Phosphate Ferric Sulfate flocculants the amount of Fe_4.67(SO₄)₆(OH)₂·20H₂O,FeHSO₄·4H₂O,Na₂HPO₄·2H₂O.etc in Polymeric Phosphate Ferric Sulfate flocculants was most. So,there was not simplicial compound other then complex reaction between PFS and Na₂HPO₄.This subject is on basis of the preparation of the polymeric phosphate sulphate flocculant, to study the effective and optimization conditions of using the complex coagulant to treat domestic sewage and algae of pond water.In the experiment of using PPFS to treat the domestic wastewater, we had studied the impact of n(PO₄^3-)/n(Fe), OH/Fe, dosage and pH in removal COD and turbidity of domestic sewage. The experimental results showed that: In neutral and alkaline conditions, we got the best results of flocculation and indicators, when n(PO₄^3-)/n(Fe)=0.3, OH/Fe=0.2, dosage=70mg/L, especially the pH value between 7 and 8. And we compared properties of PPFS, PFS for domestic sewage disposal. In addition, we approach the performance of PPFS in disposal TP.In the experiment of using PPFS to disposal algae of pond water, we have studied the impact of dosage and pH value in removal algae. The experimental results show that: removal rate was as high as 98% when pH value was between 6 and 9. It was needed very few products in the removal of the algae. It was shown that the removal rate of algae is high when Its dosage is less than 50mg/L, as the removal rate as high as 97%. Furthermore, we can get the best effect when the dosage was 30 mg/L., the removal rate could come up to 98%. Meanwhile, we compared properties of PPFS, PFS for disposal algae of pond water.