Nanoparticles (leading image) effectively break down toxins and are magnetic, making them easily recoverable for reuse (bottom image). Credit: Adapted from ACS Applied Materials & & Interfaces 2022, DOI: 10.1021/ acsami.1 c23466.
Membrane filters do not require much energy to purify water, making them popular for wastewater treatment. To keep these materials in tip-top condition, theyre typically cleaned with large amounts of strong chemicals, but a few of these representatives ruin the membranes in the process. Now, scientists reporting in ACS Applied Materials & & Interfaces have developed reusable nanoparticle catalysts that incorporate glucose to assist effectively break down impurities inside these filters without harming them.
They likewise damage polyamide membranes, which are in many commercial nanofiltration systems, and they produce toxic byproducts. A milder alternative to bleach is hydrogen peroxide, but it decomposes contaminants slowly.
One way to prevent these extra chemicals is to use the enzyme glucose oxidase, which simultaneously forms hydrogen peroxide and gluconic acid from glucose and oxygen. Jianquan Luo and associates wanted to integrate glucose oxidase and iron oxide nanoparticles into a system that catalyzes the Fenton-based breakdown of contaminants, creating a delicate and effective cleansing system for membrane filters.
Encouraged by their preliminary outcomes, the group integrated glucose oxidase and iron oxide into a single nanoparticle, connecting them with an amino bridge. They evaluated the new nanoparticles ability to clean methylene blue-soaked nanofiltration membranes, which they fouled and cleaned up for 3 cycles. After each cleaning cycle, the nanoparticles were retrieved with a magnet and reused with fresh glucose to trigger the catalyst.
First, the scientists compared the elimination of natural pollutants from polyamide filters by the glucose oxidase enzyme and iron oxide nanoparticles to other cleaning approaches, including the standard Fenton response. They discovered this technique transcended at breaking down the typical pollutants bisphenol A and methylene blue, while also preserving more of the membrane structure.
Motivated by their preliminary results, the team combined glucose oxidase and iron oxide into a single nanoparticle, linking them with an amino bridge. Finally, they evaluated the new nanoparticles capability to clean methylene blue-soaked nanofiltration membranes, which they fouled and cleaned for three cycles. After each cleaning cycle, the nanoparticles were obtained with a magnet and recycled with fresh glucose to activate the catalyst.
The nanoparticles were highly effective at cleaning up the membranes, returning them to 94% of their initial water purification capacity. Since the nanoparticles dont require strong chemicals and are easily recoverable, the researchers say their new system is a “greener” and more affordable method for cleaning up nanofiltration membranes.
Reference: “Chemoenzymatic Cascade Reaction for Green Cleaning of Polyamide Nanofiltration Membrane” 2 March 2022, ACS Applied Materials & & Interfaces.DOI: 10.1021/ acsami.1 c23466.
The authors acknowledge financing from the Beijing Natural Science Foundation and the National Natural Science Foundation of China.
Jianquan Luo and colleagues wanted to integrate glucose oxidase and iron oxide nanoparticles into a system that catalyzes the Fenton-based breakdown of impurities, developing a efficient and delicate cleaning system for membrane filters.