Green Solvents Assist Environmental Sustainability

Introduction to Green Solvents

Green solvents generally refer to solvents whose chemical properties are unstable, can be degraded by soil biology or other substances, have a short half-life, and easily decay into low-toxicity or non-toxic substances. They are also known as environmentally friendly solvents. According to the twelve principles of green chemistry, green solvents should have the following characteristics:

• Obtained from renewable raw materials

  
  

• Available for large-scale use

  
  

• Green solvents have price advantages compared to traditional solvents

  
  

• Green solvents can be recycled using eco-efficient processes

  
  

• Utilized in industrial grade, avoiding energy consumption in purification processes

  
  

• Green solvents can be prepared through high atom economy and energy-saving processes

  
  

• When used as consumables, they release negligible toxicity in nature, minimizing risk

  
  

• Highly biodegradable without producing toxic metabolites

  
  

• Green solvents have similar characteristics and performance (viscosity, polarity, density, etc.) compared to common solvents

  
  

• Green solvents have thermal stability and electrochemical stability in the process

  
  

• Non-flammable

  
  

• Easy to store and transport

  
  

Types of Green Solvents

There are three types of green solvents: water, supercritical fluids, and ionic solutions.

Water

As a medium, water has its unique advantages in diluting solvents or extracting solvents. It is also the most abundant natural solvent on Earth, inexpensive, easily obtainable, non-toxic, harmless, non-flammable, non-explosive, and does not pollute the environment.

Supercritical fluids

Fluids that are above their critical pressure and critical temperature. They have excellent solvent properties, low viscosity, high density, and good mobility, mass transfer, heat transfer, and solubility. For example, supercritical carbon dioxide can be used to prepare nanoparticles. Traditional nanoparticle preparation methods require the use of organic solvents, which can impact the human body and produce large amounts of organic waste. Using supercritical carbon dioxide can avoid these issues, being non-toxic, harmless, and recyclable. Supercritical carbon dioxide can replace the old solvent freon as a solvent for the free radical polymerization reaction of fluoroacrylate monomers, with high gas production rate and easy product separation.

Lonic liquids

Substances that are in liquid form at relatively low temperatures (generally below 100°C) and composed of ions. Ionic liquids have strong dissolving abilities, can dissolve many compounds that are difficult to dissolve, improve reaction rates and product yields, and have very low volatility. During the reaction process, they do not easily volatilize, reducing environmental pollution. Additionally, ionic liquids have high thermal stability and can conduct reactions at high temperatures, expanding the scope and conditions of reactions, replacing traditional organic solvents, reducing environmental impact, and improving reaction efficiency and sustainability.