文章摘要：
Progress on Manufacturing Method of Inorganic
Polymer Coagulant Polyferric salt category
Li Mingyu
( Department of Environmental Engineering, Jinan University, Guangzhou 510632, China. E-mail: liming-yu@sohu.com)
Abstract: This paper gives a review of the manufacturing ......
me of the oxidizing reaction may be shortened further under the condition of 50℃.
The method of directed oxidation has some merits, such as simple process, easy operation,
and shorter reaction time, but the consumption of oxidizers is high and the price is expensive. So PFS made by the method does not have market competition power.
In the method of directed oxidation, literatures [9] put forward another way which was easy to operate and popularize. The way was based on some features of the instability of ferrous hydroxide and being easy to be oxidize into ferric hydroxide. Firstly, ferrous sulfate was changed into ferrous hydroxide by adding alkali in the solution of ferrous sulfate:
FeSO4 ＋ 2NH3·H2O ＝ Fe(OH)2 ＋ (NH4)2SO4 (4)
Secondly, ferrous hydroxide forming in the reaction above was oxidized into ferric hydroxide after being placed in air:
4Fe(OH)2 ＋ O2 ＋ 2H2O ＝ 4Fe(OH)3 (5)
Then , oxidizer solution was obtained though the reaction between hydrogen peroxide and ferrous sulfate according to the equation ( 1 ). Finally, PFS was made by mixing the ferric hydroxide suspension and the oxidizer solution within 2 hours under the stirred condition.
2Fe(OH)3 ＋ H2SO4 ＋ Fe2(SO4)3 ® [Fe2(OH)n(SO4)3-n/2]m ＋ H2O (6)
These reactions mentioned above can take place in room temperature. The processing equipment of the method are simple and it is easy to operate and the cost of PFS is low too.
Literature [9] reported that the stability of PFS made in this way was poorer. In fact, the instability of PFS made in other methods mentioned in following is existent too. The critical factors affecting the stability are pH, Fe3+/SO42- or adding stabilizer in PFS.
1.2 Method of catalyzing oxidation
The method of catalyzing oxidation is that ferrous sulfate is oxidized into ferric sulfate by oxidizer under the effect of catalyst. It is a major method of manufacturing PFS with ferrous sulfate. Many studies[10-15] have been made in this aspect. Under the conditions of having oxidative catalyst and suitable temperature, PFS can be made through the oxidation of ferrous sulfate, hydrolysis, and polymerization. The catalysts used in the reaction of cat 上一页 [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] ... 下一页 >>
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