Solvent Recycle Index calculator.
Quantify what fraction of solvents used in your process are recovered and recycled back into the process or recovered for reuse. A higher SRI means less solvent waste, lower costs, and a more circular process — every session stays in your browser, never on a server.
What is the Solvent Recycle Index — and why does it matter?
The Solvent Recycle Index (SRI) measures the fraction of solvents used in a chemical process that are recovered and recycled — either back into the same process or for use elsewhere. Because solvents typically account for 50–80% of all process mass (and an even higher proportion of waste), tracking and improving their recovery is one of the highest-leverage actions available in green process design.
The formula
| Symbol | Term | Units |
|---|---|---|
| $\text{SRI}$ | Solvent Recycle Index | % (0–100); ideal value = 100% |
| $\sum m_{\text{solvent, recycled}}$ | Total mass of all solvents actually recovered and recycled (distillation, membrane separation, etc.) | g (or kg) |
| $\sum m_{\text{solvent, used}}$ | Total mass of all solvents consumed in the process (reaction, extraction, wash, purification) | g (or kg) |
Include all solvents used at every stage: reaction medium, extraction solvents, wash solvents, recrystallisation solvents, and chromatography eluents. "Recycled" means the solvent is recovered in a usable form (pure enough for re-use), not simply neutralised or treated as waste.
Typical SRI by process type
| Process type / Scale | Typical SRI | Key driver |
|---|---|---|
| Large-scale industrial (bulk chemicals) | > 90% | Economically driven closed-loop systems; continuous distillation |
| Fine chemical / API manufacturing (optimised) | 60–90% | Dedicated recovery systems; some losses from residues and aqueous phases |
| Fine chemical / API manufacturing (typical) | 30–60% | Partial distillation recovery; batch processing losses |
| Academic / teaching laboratory | < 10% | No recovery infrastructure; solvents discarded as waste |
SRI in context: related solvent metrics
| Metric | What it measures | Complements SRI by… |
|---|---|---|
| Solvent Intensity (SI) | Net solvent mass per gram of product | Quantifying the absolute solvent burden on the product |
| E-factor (solvent contribution) | Solvent waste as part of total process waste per gram product | Placing solvent waste in the context of all process waste |
| PMI | Total mass of all inputs per gram of product | Capturing the full mass efficiency picture including solvents |
| CHEM21 solvent guide score | Hazard and regulatory score for solvent choice | Evaluating the intrinsic safety of each solvent selected |
Strengths and limitations
Strengths
- Direct measure of circular solvent use — rewards recovery infrastructure
- Easy to calculate from process records; no molecular weights needed
- Scale-independent: applicable from lab to manufacturing
- Immediately actionable: improvements map directly to recovery unit upgrades
- Complements E-factor and PMI without duplication
Limitations
- Does not distinguish between solvent toxicity, volatility, or hazard
- 100% SRI is technically impossible due to residual losses; practical targets depend on solvent type
- Requires accurate solvent tracking across all process steps
- Recovery quality (purity of recycled solvent) is not captured by the index
- Energy cost of distillation recovery is not reflected in SRI alone
Experiment details
Solvent streams
Enter each solvent stream used in the process: reaction medium, extraction solvents, wash solvents, recrystallisation solvents, and chromatography eluents. Enter the mass recycled only if the solvent was actually recovered in a reusable form — not simply neutralised or disposed of.
| Solvent name | Use stage | Mass used (g) | Mass recycled (g) | % recycled |
|---|
Product mass (optional — needed for solvent intensity)
Enter the mass of isolated product to calculate the net Solvent Intensity (net solvent mass per gram of product) alongside the SRI. Leave blank to calculate SRI alone.
Results
Solvent recovery by stream
Recycled vs. wasted solvent mass
Detailed breakdown & interpretation
| Solvent | Stage | Mass used (g) | Mass recycled (g) | Mass wasted (g) | % recycled | Visual |
|---|---|---|---|---|---|---|
| Enter solvent streams above to see breakdown. | ||||||
Interpretation
Save & load sessions
Sessions are stored in your browser only. No data leaves your device.
Export
Export your SRI calculation as a PDF report or CSV data file. PDF opens in a new tab and uses your browser's print function. CSV downloads directly.
Where can I read more?
References are sorted alphabetically by first author.
- ACS Green Chemistry Institute Pharmaceutical Roundtable. Solvent Selection Guide. acs.org/greenchemistry. — Industry solvent selection criteria and recovery benchmarking data for pharmaceutical processes.
- P. T. Anastas and J. C. Warner, Green Chemistry: Theory and Practice, Oxford University Press, 1998. ISBN 978-0-19-850698-0. — Original statement of the 12 Principles; Principle 5 frames the need to minimise auxiliary substances including solvents.
- C. Capello, U. Fischer and K. Hungerbühler, Green Chem., 2007, 9, 927–934. DOI. — Environmental and health assessments of solvent use in chemical industry; emphasises recovery as a key sustainability lever.
- F. P. Byrne et al., Sustainable Chem. Process., 2016, 4, 7. DOI. — The CHEM21 solvent selection guide; provides hazard scoring and recovery feasibility data for common solvents.
- C. Jiménez-González et al., Org. Process Res. Dev., 2011, 15, 912–917. DOI. — Shows solvents account for ~85% of total process mass in pharmaceutical manufacturing; PMI framework.
- R. A. Sheldon, Green Chem., 2007, 9, 1273–1283. DOI. — E-factor analysis; solvent recovery discussed as primary driver of E-factor improvement in pharmaceutical sector.
Contributors
Roles follow the CRediT taxonomy (Contributor Roles Taxonomy), adapted for educational software. Hover a contributor's name for a summary, or a column header for the definition of that role.
| Contributor |
|---|
© 2025– DodecaGreen Project. All rights reserved. · Last updated: 07/06/2026
This portal was built with the assistance of a large language model (Claude, Anthropic), which was used to generate and refine code, articulate and structure contributed ideas within the defined page format, and support iterative design decisions. All scientific content, conceptual frameworks, pedagogical choices, and final outputs were directed, reviewed, and verified by the contributors listed above.
Whilst every effort has been taken to ensure accuracy, mistakes can happen. If you notice something that doesn’t look quite right, kindly reach out to the DodecaGreen team via the Contact page.
How do I cite this page?
If you use this tool in teaching or published work, please cite the DodecaGreen portal as the source.