A 'greener' way to clean wastewater treatment filters

Date:
March 2, 2022
Source:
American Chemical Society
Summary:
Membrane filters don't require much energy to purify water, making
them popular for wastewater treatment. To keep these materials in
tip-top condition, they're commonly cleaned with large amounts of
strong chemicals, but some of these agents destroy the membranes
in the process.

Now, researchers have developed reusable nanoparticle catalysts
that incorporate glucose to help efficiently break down contaminants
inside these filters without damaging them.



FULL STORY ========================================================================== Membrane filters don't require much energy to purify water, making
them popular for wastewater treatment. To keep these materials in
tip-top condition, they're commonly cleaned with large amounts of
strong chemicals, but some of these agents destroy the membranes in the process. Now, researchers reporting in ACS Applied Materials & Interfaces
have developed reusable nanoparticle catalysts that incorporate glucose
to help efficiently break down contaminants inside these filters without damaging them.


========================================================================== Typically, dirty wastewater filters are unclogged with strong acids,
bases or oxidants. Chlorine-containing oxidants such as bleach can break
down the most stubborn organic debris. But they also damage polyamide membranes, which are in most commercial nanofiltration systems, and they produce toxic byproducts. A milder alternative to bleach is hydrogen
peroxide, but it decomposes contaminants slowly. Previously, scientists
have combined hydrogen peroxide with iron oxide to form hydroxyl radicals
that improve hydrogen peroxide's efficiency in a process known as the
Fenton reaction. Yet in order for the Fenton reaction to clean filters,
extra hydrogen peroxide and acid are needed, increasing financial and environmental costs. One way to avoid these additional chemicals is
to use the enzyme glucose oxidase, which simultaneously forms hydrogen
peroxide and gluconic acid from glucose and oxygen. So, Jianquan Luo and colleagues wanted to combine glucose oxidase and iron oxide nanoparticles
into a system that catalyzes the Fenton-based breakdown of contaminants, creating an efficient and delicate cleaning system for membrane filters.

First, the researchers compared the removal of organic contaminants
from polyamide filters by the glucose oxidase enzyme and iron oxide nanoparticles to other cleaning methods, including the traditional
Fenton reaction. They found this approach was superior at breaking
down the common contaminants bisphenol A and methylene blue, while also preserving more of the membrane structure.

Encouraged by their initial results, the team combined glucose oxidase
and iron oxide into a single nanoparticle, connecting them with an
amino bridge.

Finally, they tested the new nanoparticle's ability to clean methylene
blue- soaked nanofiltration membranes, which they fouled and cleaned
for three cycles. After each cleaning cycle, the nanoparticles were
retrieved with a magnet and reused with fresh glucose to activate
the catalyst. The nanoparticles were highly effective at cleaning
the membranes, returning them to 94% of their initial water filtration capacity. Because the nanoparticles don't require strong chemicals and are easily recoverable, the researchers say their new system is a "greener"
and more cost-effective approach for cleaning nanofiltration membranes.

The authors acknowledge funding from the Beijing Natural Science
Foundation and the National Natural Science Foundation of China.

========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jinxuan Zhang, Huiru Zhang, Yinhua Wan, Jianquan Luo. Chemoenzymatic
Cascade Reaction for Green Cleaning of Polyamide Nanofiltration
Membrane.

ACS Applied Materials & Interfaces, 2022; DOI:
10.1021/acsami.1c23466 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220302092646.htm

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