Purifying Contaminated Water With Sunlight Alone: A Portable Water-Purification Device That Works Without Chemicals

Rapidly purifying contaminated water anywhere using only sunlight, without separate chemicals, is now possible. A research team led by Professor Kim Hye-jeong of the Department of Mechanical Engineering at Korea University (President Kim Dong-One) has developed a sustainable, next-generation flexible microreactor technology that effectively eliminates contaminants from water using sunlight.

^*Microreactor: A compact device that induces chemical reactions by allowing fluids to continuously flow through micro-channels roughly the thickness of a hair. The large surface area of a microreactor provides the advantages of high reaction rates and high efficiency.

As water shortages and water pollution continue to intensify, eco-friendly water treatment technologies that purify water using natural energy instead of chemicals have drawn attention. Among these, photocatalytic water treatment, which decomposes contaminants using light energy, is a representative example, but most existing devices are built on rigid structures, making them difficult to apply to curved surfaces or outdoor field environments. Moreover, contaminated water often fails to make sufficient contact with the catalyst surface, limiting such devices’ purification efficiency.

To address these limitations, the team developed a sunlight-based flexible photocatalytic microreactor platform. The device decomposes contaminants using light energy without the use of separate chemicals, and its flexible structure allows for stable use across diverse environments.

In particular, a three-dimensional lattice structure was incorporated inside the device to improve water treatment performance. The structure mixes water flows so that contaminants make more frequent contact with the photocatalyst (TiO2) surface, and as a result, the device achieved up to 99.4% contaminant removal efficiency under continuous flow operation. These results indicate that not only the catalyst surface area but also the design of the water flows and their mixing inside the device are critical in improving the water treatment performance.

A notable feature of the device is that its structural stability is maintained even under bending or twisting. The study found that the microreactor could be deformed without breaking, even at a small radius of curvature of about 1 mm, much like a sheet of paper being crumpled or rolled up.

Furthermore, the team scaled the device up to a field-applicable size (8 cm by 16 cm) and verified its performance under outdoor sunlight, achieving a contaminant removal efficiency of 96.9%.

The research team also implemented a portable circulation system combining a small pump and a battery. The system maintained stable purification performance even under prolonged circulation, demonstrating its applicability as a portable water treatment device that can operate in outdoor environments with limited power and facilities.

Professor Kim Hye-jeong said, “The device can operate stably even when bent or twisted, and so it could be extended to portable water purifiers that can be easily operated in the field as curved-surface attachable water treatment systems and sustainable environmental remediation technologies.”

The results of this study were published online on April 30, 2026, in Chemical Engineering Journal (IF = 13.2; top 3.0% in JCR), an internationally renowned journal in chemical and environmental engineering.

^*Article title: Flexible microreactors integrating lattice micromixers for water purification

^*DOI: doi.org/10.1016/j.cej.2026.176861

^*URL: https://doi.org/10.1016/j.cej.2026.176861

This study was supported by the National Research Foundation of Korea (NRF) and the Korea Basic Science Institute (KBSI).