Sodium Bisulfite (RO Dechlorination Reducing Agent)
CAS Number: 7631-90-5
Sodium bisulfite is a fast-acting reducing agent used to neutralize free chlorine and chloramines in RO feedwater, protecting polyamide membranes from oxidative degradation. Dosed at 1–3 mg/L per 0.1 mg/L free Cl₂ to achieve ORP <200 mV before the RO lead element.
Technical Specifications
| assay | ≥98% NaHSO₃ |
| packaging | 25 kg woven polypropylene bags |
| ORP target | <200 mV after dosing (measured at RO inlet) |
| appearance | White crystalline powder |
| dissolving | Dissolve to 10–20% solution before dosing |
| dosage rate | 1–3 mg/L per 0.1 mg/L free Cl₂ |
| SO2 equivalent | ≥59% SO₂ |
Applications
- Free chlorine neutralization in RO/NF feedwater
- Chloramine reduction prior to polyamide membrane systems
- Dechlorination in drinking water RO systems
- Industrial process water dechlorination
- RO system commissioning and membrane preservation
- Seawater desalination SWRO dechlorination
Key Features
- Rapid Cl₂ neutralization: stoichiometric reaction completes in seconds at dosing point
- High purity (≥98%) minimizes sulfite loading and avoids membrane fouling from impurities
- Precisely controlled dosing prevents both under-dechlorination and excess bisulfite carryover
- Compatible with all major polyamide RO and NF membrane types
- ORP monitoring integration enables real-time dosage control
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