making process of solid polymeric ferric sulfate products polyaluminium in europe

making process of solid polymeric ferric sulfate products polyaluminium in europe
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  • Why are PFS coagulants better than ferric sulphate?
  • Therefore, as the PFS coagulants consist mainly of polymeric species, they exhibit better coagulation behaviour. It is worth noting that for a 90% removal efficiency, only 20 mg/l of PFS are required, whereas the respective dosage of ferric sulphate in this case is much higher, i.e. 30 mg/l.
  • Which oxidizing agent is used in the synthesis of PFS?
  • The synthesis of PFS commences with the oxidation of ferrous sulphate (5.59 × 10 −3 M as Fe) to ferric sulphate in highly acidic conditions (H 2 SO 4, 96 wt%). The oxidising agent was nitric acid (HNO 3, 65 wt%). FeSO4+1/2SO42−+oxidising agent→1/2Fe2(SO4)3(Step 1. Oxidation)
  • How are polymeric species of PFS determined?
  • The polymeric species of PFS are determined from the difference between the 24 h and 1 min absorbance reading. The concentration of precipitated iron species are calculated by subtracting the concentration of oligomeric and polymeric species from the total iron concentration.
  • What happens when sulfuric acid is limited in hydrolysis?
  • When the amount of sulfuric acid is limited, the hydroxide ion will replace the sulphate ion in the hydrolysis stage and therefore, the polymerisation will occur: Fe2(SO4)3+nOH−→Fe2(OH)n(SO4)3−n/2+n/2 SO42−(Step 2. Hydrolysis)mFe2(OH)n(SO4)3−n/2→[Fe2(OH)n(SO4)3−n/2]m(Step 3. Polymerisation) 2.2. Synthesis of PFS