Ras
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The study.
Ascorbic Acid
Sodium Ascorbate
Their experiment:
Their results:
Their conclusion:
Ascorbic Acid
One gram of ascorbic acid will neutralize 1 milligram per liter of chlorine per 100 gallons of water. The reaction is very fast. The chemical reaction (Tikkanen and others 2001) of ascorbic acid with chlorine is shown below:
C5H5O5CH2OH + HOCL → C5H3O5CH2OH + HCl + H2O
Ascorbic acid + Hypochlorous acid → Dehydroascorbic acid + Hydrochloric acid + water
Approximately 2.5 parts of ascorbic acid are required for neutralizing 1 part chlorine.
Sodium Ascorbate
Sodium ascorbate will also neutralize chlorine. It is pH neutral and will not change the pH of the treated water. Sodium ascorbate is preferable for neutralizing high concentrations of chlorine.... The reaction (Tikkanen and others 2001) of sodium ascorbate with chlorine is shown below:
C5H5O5CH2ONa + HOCL → C5H3O5CH2OH + NaCl + H2O
Sodium ascorbate + Hypochlorous acid → Dehydroascorbic acid + Sodium chloride + water
Approximately 2.8 parts of sodium ascorbate are required to neutralize 1 part chlorine.
Their experiment:
The San Dimas Technology and Development Center project leader set up a small experiment to evaluate water changes during the use of sodium ascorbate or ascorbic acid to neutralize a strong chlorine solution (figure 2). The experiment consisted of:
- Making a strong chlorine solution (approximately 50 milligrams per liter chlorine).
- Neutralizing the chlorine solution with either ascorbic acid or sodium ascorbate.
- Monitoring pH, temperature, dissolved oxygen, total chlorine, and free chlorine after each step.
Their results:
Ascorbic Acid pH Temperature (℃) Dissolved Oxygen (mg/L) Total Chlorine (mg/L) Free Chlorine (mg/L) 5 gal tap water 7.6 22.3 8.3 0.75 0.05 +15 mL -6% sodium chloride 8.0 21.7 9.7 66.6 47.8 +2.5 g ascorbic acid 6.2 21.1 5.7 0.00 0.02
Sodium Ascorbate pH Temperature (℃) Dissolved Oxygen (mg/L) Total Chlorine (mg/L) Free Chlorine (mg/L) 5 gal tap water 7.6 22.7 9.5 0.79 0.05 +15 mL -6% sodium chloride 8.1 21.7 9.1 52.6 47.6 +2.5 g sodium ascorbate 7.0 21.1 6.7 0.02 0.00
Their conclusion:
Vitamin C effectively neutralizes chlorine and is safer to handle than sulfur-based dechlorination chemicals. The sodium ascorbate form of vitamin C has less [e]ffect on pH than the ascorbic acid form. When neutralizing a strong chlorine solution, both forms of vitamin C will lower slightly the dissolved oxygen of the treated water. If passive dechlorination is not practical, we recommend a form of vitamin C.