Dechlorination Products - Sodium Thiosulfate
Product Description Product Assay. WT. % Specific Gravity 25ºC pH 5%
solution
30% solution 30.0 1.28 8.0
Anhydrous 97.0 1.70 8.0
Pentahydrate 99.2 1.70 8.0
Chemistry of Dechlorination Chemical Reaction Theoretical Use Ratio
Sodium Thiosulfate (pH 11) Na2S2O3 + 4CI2 + 5H2O (to) 2NaHS04 + 8HCI
0.556
Sodium Thiosulfate (pH 6.5) Na2S2O3 + CI2 + H2O (to) Na2S04 + S +
2HCI 2.225
Sodium Bisulfite Na2HSO3+ CI2 + H2O (to) NaHS04 + 2 + 2HCI 1.455
Sodium Sulfite Na2SO3+ CI2 + H2O (to) Na2S04 + 2 +2HCI 1.775
Sulfur Dioxide SO3+ CI2 + 2H2O (to) H2S04 + 2HCI 0.903
Hydrogen Peroxide H2O2+ CI2 (to) 2HCI + 02 (g) 0.488
Freeze Point Information
Solutions of all the dechlorination agents will freeze in cold
temperatures. However, this problem can be minimized with careful
planning. Options include:
Housing the chemical in an existing storage facility
Storing the chemical in tanks designed for cold weather
Burial of tanks and lines underground
Choice of Dechlorination Agent
Although all the products listed are effective dechlorination agents,
the correct choice depends upon the specific use location and the
type of effluent being treated. JCI can advise you on the best
dechlorination agent for your situation. We have in-depth experience
in a broad range of end-use applications. We supply products and
technical expertise to the chloralkali, pulp and paper, textile and
municipal wastewater industries. The table below lists the advantages
and disadvantages of the various dechlorination agents:
Chemical Advantages Disadvantages
Sodium
Thiosulfate Significant use history
Non-toxic, non-corrosive, easy to use
Low initial capital costs
Easy to inject
Solutions subject to freezing in cold weather
Sodium
Bisulfite Significant use history
Easy to inject
Low use ratio
Sodium bisulfite is corrosive
Solutions subject to freezing in cold weather
Sodium
Sulfite Significant use history
Non-toxic, non-corrosive, easy to use
High use ratio
Solutions subject to freezing in cold weather
Sulfur
Dioxide Significant use history
Inexpensive for large installations
Injection equipment similar to that for chlorine gas can be used
Corrosive and hazardous to use
Initial capital costs are high
May increase hazard liability insurance
Requires special storage and handling equipment
Expensive for small installations
Hydrogen
Peroxide Easy to inject
Does not remove chloramines at a useful rate
Highly unstable and subject to deterioration
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Received on Wed Feb 05 2003 - 11:16:52 EST