Issue 9, 2007

What is a green solvent? A comprehensive framework for the environmental assessment of solvents

Abstract

Solvents define a major part of the environmental performance of processes in chemical industry and also impact on cost, safety and health issues. The idea of “green” solvents expresses the goal to minimize the environmental impact resulting from the use of solvents in chemical production. Here the question is raised of how to measure how “green” a solvent is. We propose a comprehensive framework for the environmental assessment of solvents that covers major aspects of the environmental performance of solvents in chemical production, as well as important health and safety issues. The framework combines the assessment of substance-specific hazards with the quantification of emissions and resource use over the full life-cycle of a solvent. The proposed framework is demonstrated on 26 organic solvents. Results show that simple alcohols (methanol, ethanol) or alkanes (heptane, hexane) are environmentally preferable solvents, whereas the use of dioxane, acetonitrile, acids, formaldehyde, and tetrahydrofuran is not recommendable from an environmental perspective. Additionally, a case study is presented in which the framework is applied for the assessment of various alcohol–water or pure alcohol mixtures used for solvolysis of p-methoxybenzoyl chloride. The results of this case study indicate that methanolwater or ethanolwater mixtures are environmentally favourable compared to pure alcohol or propanolwater mixtures. The two applications demonstrate that the presented framework is a useful instrument to select green solvents or environmentally sound solvent mixtures for processes in chemical industry. The same framework can also be used for a comprehensive assessment of new solvent technologies as soon as the present lack of data can be overcome.

Graphical abstract: What is a green solvent? A comprehensive framework for the environmental assessment of solvents

Article information

Article type
Paper
Submitted
01 Dec 2006
Accepted
22 Feb 2007
First published
09 Mar 2007

Green Chem., 2007,9, 927-934

What is a green solvent? A comprehensive framework for the environmental assessment of solvents

C. Capello, U. Fischer and K. Hungerbühler, Green Chem., 2007, 9, 927 DOI: 10.1039/B617536H

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