Understanding Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS)

PFAS are a class of chemicals known for their high chemical stability and surfactant properties, widely used in various industrial sectors, including semiconductor manufacturing, metalworking, and lubricant production. Due to their unique hydrophobic and oleophobic characteristics, PFAS have been considered essential for enhancing the efficiency of machining processes and improving product quality. However, their high stability and persistence have raised significant environmental and health concerns.

In metalworking, PFAS are commonly added to cutting fluids and lubricants as surfactants to improve cooling and lubrication effects. The fluorocarbon chain structure of PFAS allows them to form stable films on metal surfaces, reducing friction and wear, thereby extending tool life and enhancing machining precision.

For example, perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) have been widely used in various metal cutting fluids and lubricant formulations to enhance anti-rust and lubrication properties. Moreover, these compounds can remain stable under extreme conditions such as high temperatures and pressures, which is particularly important for precision metalworking in industries like aerospace and medical device manufacturing.

The Gradual Phase-Out of PFAS

The use of PFAS in metalworking and lubricants also presents potential environmental and health risks. These substances are extremely difficult to degrade, have bioaccumulative properties, and can enter natural water bodies through wastewater discharge. Waste fluids, cutting fluids, and coolants used in metalworking often contain significant amounts of PFAS.

If not properly treated, these fluorinated compounds can further contaminate soil and groundwater, posing threats to ecosystems and human health. Studies have shown that PFAS can disrupt the human endocrine system and are associated with various health issues, including cancer, immune system impairment, and reproductive problems.

As global concerns about the environmental impact of PFAS increase, many countries and regions have begun to tighten regulations on these compounds. The U.S. Environmental Protection Agency (EPA) has listed PFOS, perfluorooctanoic acid (PFOA), and their derivatives under the Toxic Substances Control Act, requiring reduced usage in industrial processes or the search for alternatives.

The European Union has also imposed strict restrictions on the use of various PFAS substances under the Stockholm Convention to minimize their environmental and health impacts. These regulatory measures have prompted the metalworking industry to seek PFAS-free alternatives and more environmentally friendly cutting fluids and lubricant formulations.

PFAS-Free Lubricants in Metalworking

In the formulation of metalworking lubricants, PFAS-free alternatives are gaining attention. These alternatives aim to reduce or eliminate the use of PFAS, thereby lowering the risk of environmental pollution. Some alternative technologies, such as plant-based lubricants and synthetic ester lubricants, not only offer similar anti-rust and lubrication properties but also have better biodegradability and environmental compatibility. However, the cost and technical requirements of these alternatives remain a challenge, necessitating further research and development to ensure their performance and stability across different industrial applications.

For the treatment of metalworking wastewater, traditional physical and chemical treatment methods, such as coagulation, sedimentation, and redox reactions, are not entirely effective in removing PFAS. Recent studies have shown that advanced treatment technologies, such as advanced oxidation processes (AOPs), membrane filtration, and adsorption techniques (e.g., activated carbon and resin adsorption), offer higher efficiency in removing these persistent organic pollutants. However, the application of these technologies must consider cost, energy consumption, and operational requirements, and they require further optimization and validation.

The use of PFAS in metalworking and lubricants highlights their advantages in industrial performance but also brings environmental and health risks. As environmental awareness increases and regulations tighten, the industry faces pressure to reduce PFAS usage, seek alternatives, and improve wastewater treatment technologies. In the future, innovations in metalworking will need to balance efficiency and environmental requirements, promoting a sustainable industrial transformation.

◆ Quoted from: Springer Nature

◆ Source: https://rdcu.be/dSOkJ