Azeotropes as Powerful Tool for Waste Minimization in Industry and Chemical Processes

Abstract

Aiming for more sustainable chemical production requires an urgent shift towards synthetic approaches designed for waste minimization. In this context the use of azeotropes can be an effective tool for “recycling” and minimizing the large volumes of solvents, especially in aqueous mixtures, used. This review discusses the implementation of different kinds of azeotropic mixtures in relation to the environmental and economic benefits linked to their recovery and re-use. Examples of the use of azeotropes playing a role in the process performance and in the purification steps maximizing yields while minimizing waste. Where possible, the advantages reported have been highlighted by using E-factor calculations. Lastly azeotrope potentiality in waste valorization to afford value-added materials is given.

A Waste‐Minimized Approach to Cassar‐Heck Reaction Based on POLITAG‐Pd0 Heterogeneous Catalyst and Recoverable Acetonitrile Azeotrope

“…Although GVL, [9h] N ‐hydroxyethylpyrrolidone (HEP), [9b] and glycerol‐based deep eutectic solvent (DES) [9a] have been shown to be valid alternatives to toxic dipolar aprotic solvents by allowing high isolated yields and also being possibly recoverable, [9a,b] they generally require an extraction work‐up, which negatively influences the E‐factor calculation. The use of a minimum‐boiling‐point azeotropic mixture allows an easy recovery accompanied with solvents and energy saving [15] …”

“…The use of a minimum‐boiling‐point azeotropic mixture allows an easy recovery accompanied with solvents and energy saving. [15] …”

“…Among the latter, a good option is offered by aqueous recoverable azeotropes that, being easily recoverable, can also be reused solving their dispersion and disposal issues [15] . The possibility to recover the reaction medium is one of the key pillars to aim for a waste minimization also according to the EPA (Environmental Protection Agency) policies [16] .…”

“…Among the latter, a good option is offered by aqueous recoverable azeotropes that, being easily recoverable, can also be reused solving their dispersion and disposal issues. [15] The possibility to recover the reaction medium is one of the key pillars to aim for a waste minimization also according to the EPA (Environmental Protection Agency) policies. [16] Furthermore, the combination of an organic solvent with water can also be an effective tool to improve the process efficiency by increasing the combination of compounds soluble in different solvents.…”

Biomass Waste-Derived Pd–PiNe Catalyst for the Continuous-Flow Copper-Free Sonogashira Reaction in a CPME–Water Azeotropic Mixture

“…They can allow the opportunity of exploiting both types of media still acting as a single recoverable substance. In this view, they can constitute an effective tool for minimizing waste while allowing a high chemical efficiency. − To this aim, we have been attracted by the peculiar properties of cyclopentyl methyl ether (CPME). This solvent forms a heterogeneous aqueous azeotrope, which boils at 83 °C. , In addition, CPME is also very interesting as it is produced from petrochemical waste with a 100% atom economy process, and it features very good toxicity and safety profiles .…”