A “Greener” Way To Clean Wastewater Treatment Filters With Reusable Nanoparticle Catalysts

一种用可重复使用的纳米颗粒催化剂清洁废水处理过滤器的“绿色”方法

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Nanoparticles (top image) efficiently break down pollutants and are magnetic, making them easily recoverable for reuse (bottom image). Credit: Adapted from ACS Applied Materials & Interfaces 2022, DOI: 10.1021/acsami.1c23466

纳米粒子（上图）可有效分解污染物并具有磁性，使其易于回收再利用（下图）。 图片来源：改编自 ACS Applied Materials & Interfaces 2022，DOI：10.1021/acsami.1c23466

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.

膜过滤器不需要太多能量来净化水，因此在废水处理中很受欢迎。为了使这些材料保持最佳状态，通常使用大量强化学物质对其进行清洁，但其中一些试剂会在此过程中破坏膜。 现在，在ACS 应用材料和界面（APPLIED MATERIALS & INTERFACES）上报道的研究人员已经开发出可重复使用的纳米颗粒催化剂，其中掺入了葡萄糖，以帮助有效分解这些过滤器内的污染物，而不会损坏它们。

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.

通常，脏污的废水过滤器不会被强酸、强碱或氧化剂堵塞。漂白剂等含氯氧化剂可以分解最顽固的有机碎屑。 但它们也会损坏大多数商业纳滤系统中的聚酰胺膜，并产生有毒的副产品。 一种较温和的漂白剂替代品是过氧化氢，但它会缓慢分解污染物。

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.

此前，科学家已将过氧化氢与氧化铁结合形成羟基自由基，从而提高过氧化氢在芬顿反应过程中的效率。 然而，为了使芬顿反应清洁过滤器，需要额外的过氧化氢和酸，从而增加了财务和环境成本。 避免这些额外化学物质的一种方法是使用葡萄糖氧化酶，它同时从葡萄糖和氧气中形成过氧化氢和葡萄糖酸。 因此，Jianquan Luo 及其同事希望将葡萄糖氧化酶和氧化铁纳米颗粒结合到一个系统中，以催化基于芬顿反应的污染物分解，为膜过滤器创建一个高效而精细的清洁系统。

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.

首先，研究人员将通过葡萄糖氧化酶和氧化铁纳米颗粒从聚酰胺过滤器中去除有机污染物与其他清洁方法（包括传统的芬顿反应）进行了比较。他们发现这种方法在分解常见污染物双酚A 和亚甲蓝方面表现出色，同时还保留了更多的膜结构。

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.

受到初步结果的鼓舞，该团队将葡萄糖氧化酶和氧化铁组合成一个纳米颗粒，并通过氨基桥将它们连接起来。最后，他们测试了新的纳米颗粒清洁亚甲蓝浸泡过的纳米过滤膜的能力，他们污染并清洁了三个循环。在每个清洁周期后，用磁铁回收纳米颗粒并与新鲜葡萄糖一起重新使用以激活催化剂。

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.

纳米颗粒在清洁膜方面非常有效，使它们恢复到其初始水过滤能力的 94%。 由于纳米颗粒不需要强化学物质且易于回收，研究人员表示，他们的新系统是一种清洁纳米过滤膜的“更环保”且更具成本效益的方法。