Calculate the Environmental Factor of any chemical process from the actual masses of inputs and isolated product.
The E-factor (Environmental Factor), introduced by Roger Sheldon in 1992, is a direct experimental measure of how much waste a chemical process generates per unit of desired product. Unlike atom economy, E-factor captures everything that actually happens in the lab, including solvents used, reagents not incorporated, workup waste, and by-products, making it a powerful tool for real-world process evaluation.
| Symbol | Term | Units |
|---|---|---|
| \(E\) | E-factor (Environmental Factor) | dimensionless (kg kg−1); ideal value = 0 |
| \(m_{\text{waste}}\) | Total mass of all process outputs except the desired product (side-products, spent solvent, wash liquors, excess reagents, drying agents) | kg (or g) |
| \(m_{\text{product}}\) | Mass of isolated desired product | kg (or g) |
"Waste" is everything that is not the desired product: unreacted starting materials, by-products, solvents not recovered, spent catalysts, wash liquors, and any auxiliary materials. A lower E-factor is always better. Recovered and recycled materials reduce the waste total.
| Industry segment | Product tonnage (p/a) | E-Factor (kg waste/kg product) |
|---|---|---|
| Oil refining | 106–108 | < 0.1 |
| Bulk chemicals | 104–106 | < 1–5 |
| Fine chemicals | 102–104 | 5–50 |
| Pharmaceuticals | 10–103 | 25–>100 |
Adapted from R. A. Sheldon, "The E factor at 30: a passion for pollution prevention", Green Chem., 2023, 25, 1704–1728.
| Metric | What it measures | Stage |
|---|---|---|
| Atom Economy (AE) | Theoretical fraction of reactant mass in desired product (from equation) | Design |
| % Yield | Fraction of theoretical product actually isolated | Experimental |
| E-factor | Mass of all waste per mass of product (all inputs, real scale) | Experimental |
| PMI (Process Mass Intensity) | Total mass of all inputs per mass of product; PMI = E-factor + 1 | Experimental |
| RME (Reaction Mass Efficiency) | AE × yield × stoichiometric factor — combined practical efficiency | Both |
Enter all materials used in the process: reagents, solvents, catalysts, and workup/purification materials. If a solvent or catalyst is recovered and recycled, enter that mass in "Recovered" — it is subtracted from the waste total. Do not enter the product here.
| Material name | Category | Mass used (g) | Recovered (g) | Net waste (g) |
|---|
Enter the mass of each desired product actually isolated (not theoretical yield). If your process produces multiple valuable products, add each one — their combined mass forms the denominator of the E-factor.
| Product name | Mass isolated (g) |
|---|
| Material | Category | Mass used (g) | Recovered (g) | Net waste (g) | % of waste | Visual |
|---|---|---|---|---|---|---|
| Enter input materials and product above to see breakdown. | ||||||
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