Preparation method of polyferric sulfate (PFS)

Abstract

The invention relates to a preparation method of polyferric sulfate (PFS). The method comprises the following steps of dissolving a certain amount of bivalent ferric salt into water; adjusting the pH value through sulfuric acid, and heating and stirring in a water bath; adding a certain amount of persulfate serving as an oxidant to oxidize Fe<2+> in solution; and performing hydrolytic polymerization to obtain PFS. A novel method is provided for the preparation of PFS. The method disclosed by the invention has a simple process; a prepared PFS coagulant has a good coagulation effect and high turbidity removal rate of up to 94.6 percent; moreover, various indexes of the prepared PFS coagulant are consistent with the requirement of PFS serving as a GB14591-2006 water treatment agent; furthermore, the using amount of ferrous sulfate required to be added in the method is small, the adding speed of sodium persulfate serving as an oxidant is easy to control, and ferrous iron is fully oxidized; and moreover, the method has the advantages of simple operating process, no corrosion, wide pH application range, low cost, high performance and a very good market prospect.

Description

technical field [0001] The invention belongs to the technical field of research on coagulants used for industrial waste water, urban sewage and water supply treatment, and in particular relates to a preparation method of polyferric sulfate. Background technique [0002] Coagulant is a polymer that can form flocs from fine-grained solids dispersed in liquids. It can be mixed with water in any ratio and can be widely used in the treatment of industrial wastewater, urban sewage and water supply. At present, the commonly used coagulants are basic aluminum chloride, polyferric sulfate, ferric chloride and aluminum sulfate. Polyferric sulfate has the following advantages: fast formation of flocs, dense particles, fast settling speed, good removal effect on COD, BOD, turbidity, chroma and heavy metals in various wastewater, and pH value of treated wastewater And the water temperature adapts to a wide range, and has good dehydration for sludge. [0003] The commonly used method fo...

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Problems solved by technology

[0003] The commonly used method for preparing polyferric sulfate is mainly the direct oxidation method, and the direct oxidation method mainly includes H 2 o 2 Oxidation method, KClO 3 / NaClO 3 Oxidation method, HNO 3 Oxidation method and NaClO oxidation method, etc., the direct oxidation method is due to the high price of the oxidant used, so the product cost is relatively high, and there are some other problems in the reaction process, such as H 2 o 2 Oxidation, the reaction process is very violent and releases a lot of heat, and the high temperature accelerates the H 2 o 2 Decomposition, causing waste of oxidants and at the same time it is difficult to reasonably control the rate of oxidant injection; KClO 3 / NaClO 3 The product of the oxidation process has residual Cl - and ClO 3 - Not suitable for water treatment, and KClO 3 The price is relatively expensive, which limits its large-scale industrial production, and a large amount of Cl will be produced in the reaction process 2 , leakage will cause air pollution; while HNO 3 The oxidation method also needs to increase the tail gas absorption device, resulting in complex equipment structure and increased process cost

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