Optimization Guide is a way to search through database to find solvents that are realistic for your application based on safety, efficiency, and affordability. It is best paired with the HSPiP Optimizer Function which blends solvents changing the overall HSP value. Not only can it help you find solvents, but it can help you make blends that work most efficiently for your application.
1) Safety - EHS Information
In the Optimization Guide, the left side of the screen will show a section called “EHS Information” which is where you set your definition of safe. To do this you have to think about the environment in which you are using your solvent. What kind of PPE will the user be wearing? Is there ventilation? Can you properly store flammable liquids? Create a list of hazards that must be avoided to generate a list of solvents that are safe for your application and environment.
One way to accomplish this is to go through the GHS Health Hazard Categories (organized by endpoint) and manually decide what the toxicity limit for each endpoint should be. The GHS scale has the lowest score as the most hazardous.
Another way to approach finding safer solvents is using the NFPA Health Hazard Rating which is an overview on how harmful the chemical is to human health. The NFPA Health rating is the same rating in the blue square of the NFPA Diamond found on SDS sheets. The NFPA score is a score from 0 to 4, with 0 being the safest value and 4 being the most hazardous value.
In this section, you can also choose a Flammability Limit through GHS Flammability Limit, NFPA Fire hazard Rating, or by a specific flash point under “Physical Properties”.
For your first search, start with the safest standards and only when you can’t find a suitable answer expand the search to include higher (but manageable) hazards.
2) Efficiency - Solubility Theory and Physical Properties
A way to determine a solvent’s effectiveness is by using solubility theory. This database uses the Hansen Solubility Parameters (HSP) Theory to predict if a solvent will dissolve a solute. More information about HSP theory and its analytical software Hansen Solubility Parameters in Practice (HSPiP) can be found at their website.
In HSP Theory, every chemical has an HSP value which is the quantified strength of 3 intermolecular forces: (D) London Dispersion Force, (P) Dipole-Dipole Force, and (H) Hydrogen Bonding. These values are mapped in 3D space with solvents represented as points and solutes represented as spheres (points with a radius). If the solvent’s point is within the solute’s sphere, then the solvent will dissolve the solute. If the solvent’s point is outside of the sphere, then the solvent will not dissolve the solute (think like dissolves like). The closer a solvent’s value is to the center of a solute’s sphere, the more effectively it will dissolve that solute.
An exciting aspect to this theory is that when two miscible solvents are blended together the HSP of the solution changes to be a weighted average of the two HSP values. This means that you can create solutions that fall exactly on the solute’s HSP value for optimal dissolution. The Optimization Guide facilitates finding safe solvents that can be used in the HSPiP Optimizer function to custom create extremely effective solutions for solvent replacement, as the solvents selected can be downloaded in an .hsdx file. The Optimization Guide can also be used for finding single solvent replacements based on the same principles of HSP theory.
Usually for a solvent to be effective, not only does it need to have a specific HSP value, but it also depends on other specific physical properties. For example when creating a paint and coatings remover, TURI’s team discovered that having a small molar volume was a crucial part of having an effective removal. Once you understand what physical properties help the solvent achieve its performance, use the “Physical Properties” section to fill in the requirements.
3) Affordability - Cost
Although the listed prices are not completely accurate, they still give an idea of which solvents can be affordable. The best way to determine if you can afford basic testing with a solvent is looking at the Lab Scale cost.
Here is a quick cheat to understand the prices:
$0.1/g = $50/500 g
$0.2/g = $100/500 g
$1 /g = $500/500g
The bulk costs aren’t as accurate because they are typically priced by the 1 – 25 kg scale and would be much cheaper by the ton. If you are searching for something that would potentially need solvents above the lab scale
Sometimes initially searching without a cost restriction is a good option to see how many options there could be, because inquiring with the chemical manufacturer or asking for a sample will always bring the price down.
Click select all or just select the ones you want. Press export, this will export as a .hsdx file which can be plugged directly into the HSPiP software. A pop up will ask what you want to name the file. The file will be downloaded and saved under the computer’s downloads.
Other TURI Tools
Green Solvents Resources
Hansen Solubility Parameters Resources
This is a tool that can be misused. TURI is not responsible for the misuse of this tool and does not claim that every solvent in this database is safe for your application. Please do further research on each solvent to determine if it is safe for your application.