New filtration technology could be game-changer in removal of Pfas ‘forever chemicals’ | Pfas

New filtration technology developed by Rice University could absorb certain Pfas “permanent chemicals” at a rate 100 times higher than before, which could significantly improve pollution control and speed up remedial action.

The researchers also claim to have found a way to destroy Pfas, although both technologies face a significant challenge when deploying on an industrial scale.

A new peer-reviewed paper details a layered double hydroxide (LDH) material based on copper and aluminum that absorbs long-chain Pfas up to 100 times faster than commonly used filtration systems.

“This material is going to be important for directing research on Pfas destruction in general,” said Michael Wong, director of Rice’s Water Institute, a Pfas research center.

Pfas are a class of at least 16,000 compounds often used to help products resist water, stains and heat. They are called “forever chemicals” because they do not break down or accumulate naturally in the environment, and they are linked to serious health problems such as cancer, kidney disease, liver problems, immune disorders and birth defects.

Current filtration technology like granular activated carbon, reverse osmosis, or ion exchange absorbs Pfas in the water, and the chemicals captured in the filter must be stored in hazardous waste facilities or destroyed. Destruction of chemicals usually involves a thermal process that subjects them to high heat, but leaves toxic byproducts or essentially breaks the larger Pfas into smaller Pfas. No technology completely destroys Pfas on an industrial scale.

Wong said Rice’s nonthermal process works by absorbing and concentrating Pfas to high levels, allowing them to be destroyed without high temperatures.

The LDH material Rice developed is a variation of similar materials previously used, but the researchers replaced some aluminum atoms with copper atoms. The LDH material is positively charged and the long-chain Pfas are negatively charged, which causes the material to attract and absorb chemicals, Wong said.

“Lo and behold, it absorbs it 100 times faster than other materials available,” Wong added.

Pfa is virtually indestructible because its carbon atoms are bonded to fluoride, but Rice found that the bonds could be broken if the chemicals in the material were heated to 400-500°C – a relatively low temperature. Fluoride is trapped in the LDH material and is bound to calcium. Leftover calcium fluoride is safe and can be disposed of in a landfill, Wong said.

The process works with some long-chain Pfas that are among the most common water pollutants, and it also absorbs some smaller Pfas that are common. Wong said he is confident the material can be used to absorb a wide range of Pfas, especially if they are negatively charged.

Most new Pfas removal systems do not work on an industrial scale. Wong said the new material has an advantage because its absorption rate is so strong that it can be used repeatedly and it is a “drop of material,” meaning it can be used with existing filtration infrastructure. This removes one of the biggest cost barriers.

Laura Orlando, a Pfas researcher at the nonprofit Just Zero and a civil engineer who works on waste management design, said she is always skeptical of claims about total destruction of Pfas and new filtration technologies because the processes are so complex in real-world conditions. Other challenges such as workplace safety, or regulations and permits, should be considered.

“We’re going to need as much technology as possible to treat Pfas in drinking water, and if it works on a large scale on wastewater, then that would really be something to pay attention to,” Orlando said.