Eastman cellulosic membrane materials are especially advantageous when filtering process streams that are highly fouling. In addition, these materials offer economical options compared to other alternative polymers.
The following chart is a general comparison of polymers commonly used to make membranes.
|
Material |
pH range |
Cost |
Tensile strength, mPa |
Oxidant resistance,
ppm hours of chlorine |
Strengths |
Weaknesses |
Cellulosic derivatives
(CA, CDA, CTA) | Narrow, 4–9 | Low | Moderate, 30–60 | High, >104 | High fouling resistance; low cost; highly hydrophilic
| Lower flux rates; limited pH range |
| Polyamides | Wide, 2–11 | High | High, 130–150 | Low, <500 | High mechanical strength; very high rejection level
| Destroyed by chlorine;
prone to biofouling |
| Fluorinated polymers (PVDF) | Moderate, 2–10 | High | Moderate, 30–60 | High, >104 | Chlorine resistant; moderate to high rejection level
| High cost; difficult to produce; hydrophobic |
| Polysulfone and polyester sulfone | Wide, 1–13 | Moderate | Moderate to high, 70–90 | Moderate, <104 | High rejection level; wide pH range; high temperature resistance
| Limited tolerance to chlorine |