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 methanol-water or ethanol-water 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.

X-ray spectroscopy for chemistry in the 2-4 keV energy regime at the XMaS beamline: ionic liquids, Rh and Pd catalysts in gas and liquid environments, and Cl contamination in γ-Al2O3

“…Such solvent mixtures have been highlighted as preferable within metrics used to assess the green credentials of solvents preferred as carriers for catalytic reactions for fine chemicals production by the pharmaceutical industry (see, for example, Capello et al, 2007;Henderson et al, 2011). As palladium in many forms is one of the most used catalysts for such conversions, understanding how it might interact with such solvents is of intrinsic interest.…”

Introducing natural thermoplastic shellac to microfluidics: A green fabrication method for point-of-care devices

“…However, Capello et al stated that ethanol is a comparably green solvent. 26 Furthermore, ethanol can be produced from renewable biomass as corn or sugar beet. In comparison to our novel fabrication method for shellac microfluidic systems described here, the fabrication of state-of-the-art microfluidic chips made of PDMS and glass would consume similar amounts of electrical energy, as the PDMS must be cured, usually at temperatures between 60 C and 100 C. 27,28 The energy demand for the fabrication of the particular materials used was not investigated specifically.…”

Pineapple peel wastes as a potential source of antioxidant compounds

“…However, methanol is a toxic organic solvent which caused several health problems [12]. Mixtures of ethanol and water are an environmentally preferable solvent [13]. Study on the pineapple as antioxidant by ethanol was considerable aginst DPPH radical and achieved at concentrations of 50 and 70% v/v.…”