A group from the National Institute of Advanced Industrial Science and Technology and Kyoto University has developed a carbon quantum dot/graphene oxide composite membrane that can treat multiple types of pharmaceuticals and personal care products (PPCPs) at once. Successful.

 Thousands of types of PPCPs are present in water used by humans, generated by human activities. Even in minute amounts, PPCPs can cause drug resistance and cause harm to humans and the ecosystem. Therefore, in order to effectively use water used by humans as reclaimed water, technology that can treat PPCPs with high efficiency is required. .

 Conventional treatment technologies have limitations in the types of PPCPs that can be treated and in treatment efficiency, as well as problems such as complicated operations, generation of toxic by-products, and high costs.On the other hand, the newly developed composite membrane has a major advantage in the advanced use of reclaimed water by being able to treat positive, negative, and neutral PPCPs at the same time.

 This new composite film creates positive and negative charges between the layers by inserting positively charged carbon quantum dots (CQDs) between the layers of negatively charged graphene oxide (GO). This creates a mixed charge type environment in which PPCPs coexist, making it possible to separate and remove PPCPs of various polarities.Due to electrostatic repulsion, both positively and negatively charged PPCPs are prevented from passing through, but since there is a strong hydrophilic environment between the membrane layers, the repulsion effect due to the difference in hydrophilicity and hydrophobicity acts to prevent neutral PPCPs from passing through. membrane permeability is also disadvantageous.In this way, it is said to be effective in simultaneously separating and removing a wide variety of PPCPs with different polarities, and in fact, high removal rates were obtained for all 37 types of PPCPs with different polarities evaluated in experiments. Compared to membranes made only of GO, not only the removal rate of negative ion type and neutral PPCPs was greatly improved, but also the removal rate of positive ion type PPCPs, which cannot be removed by GO membrane alone, which has the characteristic of being negatively charged, was improved at least. A removal rate of over 56% was achieved.

 This result is expected to be useful in the development of highly efficient recycled water treatment technology to solve global water resource issues.In the future, the company plans to proceed with research to further improve separation performance to a practical level, such as by optimizing the physicochemical structure of the composite membrane.

Paper information:[Chemical Engineering Journal] Achieving overall rejection of pharmaceuticals and personal care products of different polarities by controlling interlayer charging environment of graphene oxide membrane using carbon quantum dots

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