Dr. Nguyen Thi Thanh Hai, Institute of Environmental Technology

Antibiotic residues are classified as new pollutants in the environment due to their increased use, disposal into the environment and their biological activities. However, unlike other organic pollutants, antibiotic residues in the aquatic environment are considered a major concern because of their complex nature as well as their property of inhibiting the processes of decomposition of organic compounds. 

Removing antibiotic residues in wastewater right at the source before disposing of them into the surrounding environment is very important.

Among the group of antibiotics commonly used in the treatment of diseases, ciprofloxacin and levofloxacin are quinolone antibiotics or fluoroquinolones (FQ), which are the fourth most used drugs for humans and are useful in the treatment of postoperative infections. In order to control the risks of antibiotics in general and FQs in particular to the environment and human health, understanding their origin and treatment in the environment has been of interest to scientists around the world. 

Adsorption and photocatalysis are considered effective methods in the process of removing antibiotics due to their simple design, simple operation, relatively inexpensive and unaffected by potential toxicity, suitable for the process of handling antibiotics with high efficiency. For the photocatalytic method, the use of materials with strong adsorption, high photocatalytic ability in the visible light region, and easy recovery for reuse in the antibiotic treatment process are essential. Currently, Bismuth oxyhalide material (BiOX, X = Cl, Br, I) is a medium form of capillary material that is attracting the attention of scientists around the world thanks to its unique layered structure that can create effective separation of electron-hole pairs and achieve high photocatalytic performance. Among BiOX materials, BiOI has the smallest band energy (~1.93 eV) and strong absorption in visible light. Therefore, using the adsorption ability and photocatalytic effect of BiOI to decompose antibiotics in the aquatic environment has outstanding advantages over traditional treatment methods.

Medium capillary material BiOI nanoparticle size from ~15nm, with high adsorption capacity and photocatalysis, can treat antibiotics with sunlight sources

After the research process, the team successfully fabricated bismuth oxyiodide - BiOI material capable of adsorbing and photocatalyzing the decomposition of antibiotics ciprofloxacin and levofloxacin (belonging to the fluoroquinolone group) in the aquatic environment. At the same time, it is possible to build a process for manufacturing BiOI materials under room temperature (BiOI-R) and heat capacity (BiOI-S) methods. The procedure is easy to perform, has high repeatability and stability.

In addition, the research team has successfully fabricated a photocatalytic test system using BiOI-S materials and applied to remove antibiotic residues ciprofloxacin and levofloxacin in medical wastewater samples, the antibiotic treatment efficiency reached 84-89% under the sun's illumination. The results have contributed to a method that can be applied in practice to treat aquatic environments contaminated with antibiotic residues.

The 10L/day photocatalytic system treats fluoroquinolone antibiotics (ciprofloxacin, levofloxacin) in water

The product of the project is highly applicable because of the simple and convenient process of manufacturing and using materials in antibiotic treatment. Using BiOI medium capillary material to treat fluoroquinolone antibiotics (ciprofloxacin, levofloxacin) in aquatic environment is a new technological process in Vietnam. This type of technology is simple, low-cost but highly effective, comparable to the technologies being applied in advanced countries.

The project has published 01 article in the journal Environmental Progress and Sustainable Energy and 01 article in the journal Chemical Engineering & Technology (accepted for publication), are all in the SCIE list; 01 article in VAST02 magazine; 03 articles published in domestic specialized journals with ISSN index. The project has 01 decision to accept a valid application for patent registration.

The research team wishes to continue studying the decomposition process of fluoroquinolone antibiotics in general and ciprofloxacin, levofloxaxin in particular in the aquatic environment to evaluate the forms of existence as well as factors affecting the process of decomposition in the aquatic environment.

Translated by Phuong Ha
Link to Vietnamese version