Sustainable initiatives aren’t limited to carbon capture and power generation. Every industry is greening, and that also includes chemistry!

According to the Royal Society of Chemistry, green chemistry is « the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture and application of chemical products ».

Based on a proactive approach to pollution prevention, the concept, which has evolved with the increased awareness of the effects of chemical contaminants on the planet's health, is revolutionizing industrial chemistry.

The increasing importance of green chemistry is undeniable. Metallic waste and other chemical products overwhelm soil and waterways with pollutants, jeopardizing human health and ecological balance.

Although government agencies have developed environmental guidelines to regulate the production and discarding of chemical waste, green chemists go a step further by actively seeking the development of processes that promote conservation and avoid the generation of toxic pollutants.

Applying the Principles of Green Chemistry to Separation Processes

From The Twelve Principles of Green Chemistry: What It Is, & Why It Matters

Green chemistry advocates 12 principles, but they can be classified into 5 categories of improvement: waste reduction, solvent selection, reaction efficiency, safety, and chemistry.

By applying these concepts, chemists are greening separations and creating more sustainable operations.

  • 1. Waste Reduction

    Green chemistry principles minimize waste by following the 3-R rule: reduce, reuse and recycle. You can employ this rule during separations by implementing sorbent use, metal scavenging, solvent recycling, and automation.

    • Sorbent Use

      Sorbents can collect designated molecules, avoiding their release as pollutants. Functionalized silica is one such effective sorbent. pH-optimized silica products offer enhanced versatility and an ability to adsorb a wide variety of substances, including metals, dyes, proteins, genotoxins and drug molecules. The chemically modified silica can maintain a negatively charged surface with a pH of 2 or higher. As a result, it can adsorb cations under more neutral conditions and release them in a mildly acidic wash to remove impurities and restore solvents to a reusable state.

    • Metal Scavenger Applications

      Green chemistry circumvents the release of metallic waste pollution by using metal scavengers. Functionalized silica may be used to scavenge metals that would otherwise be discarded. The silica with the contained metals can be transferred to a third party, where the scavenged metals can be separated from the silica, leaving both available for reuse or safe disposal.

    • Solvent Recycling

      Solvents can be salvaged after use via distillation. And while they may not be suitable for further processing, used solvents can also be repurposed for other lab tasks (e.g., cleaning glassware).

      In addition, silica helps solve the main obstacle in recycling organic solvents. Even small amounts of water can cause problems with reactant decomposition, solubility and undesirable side reactions. Silica can serve as a molecular sieve, allowing the recovery of more solvent and minimizing waste.

    • Automation

      Green chemistry principles often favor automation over manual processing. Why? Because automation reduces solvent consumption during separations. The programming of equipment to automatically conduct step gradients in flash column chromatography (flash purification) eliminates the need for manual intervention and reduces the overall consumption of solvents during the separation.

      When compared to linear gradients, step gradients offer the benefits of speed and efficiency during the separation of a single chosen component from a complex mixture. Additionally, automated methods can use a smaller, tightly packed column while rendering the same results as a larger column would with a manual process.

  • 2. Solvent Selection

    Green chemistry practices promote the use of greener or biobased solvent alternatives. Greener solvents include those that are recyclable, plant-based or from renewable sources, such as water, ethanol made from corn, acetone, 2-MeTHF (instead of THF), and methanol (instead of acetonitrile).

    During drug discovery and development, molecular separation and purification play important roles. The associated processes, however, tend to require large volumes of solvent – irrespective of whether the purification is performed using LC, flash, or HPLC. As a result, process solvents in the drug sector bear substantial responsibility for waste production, energy usage and greenhouse emissions.

    Solvent-less chemistry is desirable, but let’s face it: it’s not usually an option in drug synthesis reactions. Thus, green chemists continue to look for ways to minimize solvent use and identify greener solvent alternatives.

  • 3. Reaction Efficiency

    Green process developers encourage atom economy—the minimization of wasted atoms— rather than the sole prioritization of percent yield. In addition, they select energy sources based on minimal economic and environmental impact, preferring catalysts such as enzymes – which are recyclable indefinitely – over stoichiometric reagents.

    According to an article from, silica, which offers an expansive surface area and tunable particle size, can serve as active catalysts in processes that are typically palladium-catalyzed, including Sonogashira and Suzuki-Miyaura couplings. Additionally, the used functionalized silica is recyclable, retaining most of its structure and activity. The silica can also be used as adjuncts to catalysts or other reagents, alleviating the purification steps required for reactant removal.

  • 4. Safety

    As we’ve mentioned, green chemistry prioritizes the use of less toxic substances and solvents. Additionally, it emphasizes hazard reduction and risk minimization. Therefore, chlorinated solvents – along with others that have been deemed hazardous – are reduced or exchanged for less toxic options whenever possible.

    Byrne et al. (Tools and techniques for solvent selection: green solvent selection guides, Sustainable Chemical Processes) explore how legislation and evolving attitudes towards environmental issues are driving the search for greener solvents.

    They reference how Europe's Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulation has deemed multiple solvents as substances of very high concern (SVHC) due to their potential to cause cancer, damage fertility, or harm unborn children. These include:

    • Ethylene glycol dimethyl ether
    • Diethylene glycol dimethyl ether
    • Trichloroethylene
    • 1,2- Dichloroethane
    • 1,2,3-Trichloropane
    • 2- Methoxyethanol
    • 2-Ethoxyethanol
    • 2-Ethoxyethly acetate

    Green solvents have relatively high health, safety, and environmental scores, and are recommended. You may want to use these instead:

    • 2-Methyltetrahydrofuran
    • N, N'-Dimethylpropyleneurea
    • 4-Methyltetrahydropyran
    • Cyclopentyl methyl ether
    • 1,3 Dioxolane
    • 1,3-Propanediol
  • 5. Chemistry

    Products or byproducts of green separations are designed to eventually degrade or become relatively harmless after their functionality is concluded, promoting environmental integration instead of pollution.

The Green Advantage of Functionalized Silica

The use of functionalized silica can help you facilitate the use of green principles. Among its advantages, it offers:

  • Low toxicity. Silica is nontoxic and nonhazardous.
  • Versatility. Functionalized silica can be used in numerous different types of reactions.
  • Low energy requirements. The silica does not require an overall increase in energy expenditure.

When using functionalized silica products, it is important to choose the right column size, injection volume, silica size, and product shape. Here are a few links to help your selection process:

For More Information

If you are shifting your lab to greener, more sustainable chemistry, SiliCycle may be able to help. Our products can increase your load and optimize your purifications. Here are a few of our greening products to explore:

  • Silica Selection Guide
  • SiliaSphere Spherical Silica Gels – The perfectly round silica particles help increase your flash cartridge load without sacrificing separation performance.
  • SiliaChrom Plus HPLC Columns – Our HPLC cartridges provide exceptional mechanical and chemical stability, complete end-capping, and a super high loading capacity.
  • SiliaSep Flash Cartridges – These superior cartridges offer improved efficiency during purifications.
  • SiliaMetS Metal Scavengers – These products eliminate the need to add solvents to remove metals and other impurities from the products.
  • E-PAK Cartridges – Metal scavengers or activated carbon in cartridge format for flow through systems allowing repeated recirculation of the solution to achieve desired purity levels.