RO membranes are usually thin-film composite (TFC) polyamide. They are sensitive to oxidants, pH extremes and some solvents. The table below gives general compatibility guidance; always check the membrane manufacturer’s datasheet.
| Chemical / condition | Polyamide TFC | Cellulose acetate | Notes |
|---|---|---|---|
| Chlorine / hypochlorite | Not compatible | Tolerant (low levels) | Dechlorinate TFC feed; use SMBS or activated carbon |
| pH range — operation | 2 – 11 | 4 – 8 | Outside range causes hydrolysis/damage |
| pH range — cleaning | 1 – 12 (short term) | 4 – 7.5 | Use manufacturer-approved cleaners |
| Citric acid cleaner | Compatible | Compatible | Good for metal oxide and calcium scale |
| Caustic soda (NaOH) | Compatible (cleaning) | Limited | Removes organic/biofouling |
| Surfactants / detergents | Limited | Limited | Use only approved membrane cleaners |
| Hydrogen peroxide | Limited / not recommended | Some tolerance | Can oxidise polyamide |
| High temperature | Max 45°C typical | Max 35°C typical | Check datasheet for exact limit |
Important: Always dechlorinate water before TFC membranes. Even low chlorine residuals will permanently damage polyamide layers.