Breakthrough Modified Photocatalytic System: A Solution for Antibiotic Removal in Vietnam’s Aquatic Environment
In recent years, antibiotic pollution has become an alarming environmental issue in Vietnam. The widespread use of antibiotics in livestock farming, aquaculture, and healthcare has led to large quantities of antibiotic residues being released into aquatic environments, negatively impacting aquatic ecosystems and accelerating the emergence of antibiotic-resistant bacteria. This poses not only a challenge for the agricultural sector but also a global public health risk repeatedly emphasized by the World Health Organization (WHO).
In response to this situation, Vietnamese scientists have been searching for green and sustainable solutions for effectively treating antibiotic contamination. Among these, photocatalytic technology—using light energy to break down harmful compounds—has shown strong potential for practical application. However, conventional photocatalytic materials still face certain limitations, such as their dependence on high-energy UV light, high fabrication costs, and inconsistent performance under natural environmental conditions.
With the aim of finding an environmentally friendly and sustainable solution, Dr. Le Phuong Thu and her research team proposed and were approved by Vietnam Academy of Science and Technology (VAST) to implement the project: “Photocatalytic Treatment of Antibiotics in Aquaculture Using Bi₂MoO₆/g-C₃N₄/Clinoptilolite Composite Materials” (code VAST07.03/23-24).
Dr. Le Phuong Thu (second from right) and her research team in the laboratory
To overcome the limitations of conventional photocatalytic materials, the research team developed a three-component composite system combining nanoscale semiconductors with clinoptilolite - a natural zeolite mineral known for its strong adsorption capacity and low cost. Using a simple hydrothermal method, the team successfully synthesized the Bi₂MoO₆/g-C₃N₄/Clinoptilolite material (abbreviated as CNBC). This material can operate efficiently under visible light, meaning natural daylight—an outstanding advantage compared with many other catalytic systems that require artificial light sources.
(a) UV–Vis DRS spectra and (b) band gap energies of the different catalysts
Analyses showed that the CNBC material possesses a large specific surface area and a band-gap energy of only 2.23 eV, enabling highly efficient absorption of visible light (natural daylight). Thanks to the tightly bonded structure between the nanoparticles, the material effectively limits the “recombination” of electrons and holes—an issue that often reduces efficiency in photocatalytic reactions.
Experimental results demonstrated that CNBC can degrade up to 87.47% of oxytetracycline (OTC) after 120 minutes and 89.04% of ciprofloxacin (CFX) after just 90 minutes of light irradiation. When incorporated into a continuous wastewater treatment system at laboratory scale, the material achieved nearly 100% efficiency, despite requiring only a small amount of catalyst (150 mg/L), saving three times the dosage typically needed by conventional systems. Notably, the CNBC material can be reused multiple times with only about a 10% reduction in performance, demonstrating high stability and sustainability—key attributes for practical application.
The research team also clarified the photocatalytic reaction mechanism, a critical factor determining treatment efficiency. Through in-depth analyses, they identified the roles of strong oxidizing radicals such as SO₄●⁻ and HO● in the antibiotic degradation process. These findings provide a solid scientific foundation for optimizing treatment performance and expanding the application of similar catalytic systems in the future.
Photocatalytic degradation mechanism of oxytetracycline (OTC) by the CNBC-30/PDS/Vis system
Notably, the team successfully developed a laboratory-scale recirculating photochemical treatment model capable of operating stably and effectively removing antibiotics from aquaculture wastewater—an environment with highly variable pollutant concentrations.
According to the evaluation of the Acceptance Council of Vietnam Academy of Science and Technology (VAST), the project led by Dr. Le Phuong Thu was recognized as having high practical value, offering a green and sustainable technological approach to addressing antibiotic pollution—an urgent environmental issue today. The Council highly commended the team’s efforts in designing and successfully operating the laboratory-scale recirculating treatment system, demonstrating its effectiveness and stability in removing antibiotic compounds under conditions close to real-world scenarios.
The research results have been published in an international SCIE-indexed journal (IF 3.5, Q1) and in one article in VAST1. The Council concluded that this is a study of high scientific quality, implemented with a rigorous methodology, producing results that exceed requirements, and unanimously rated the project as Grade A.
With a focus on developing environmentally friendly treatment solutions, the research team utilized low-cost natural materials combined with a simple synthesis process to create the Bi₂MoO₆/g-C₃N₄/Clinoptilolite photocatalyst system that is not only efficient but also stable and practical for real-world application. This achievement affirms the team’s research capability in treating wastewater from industrial, agricultural and aquaculture activities, contributing to sustainable development and the protection of public health.
Sharing the team’s direction, Dr. Le Phuong Thu said: “We aim to bring advanced treatment technologies closer to daily life, particularly in rural areas and aquaculture regions where antibiotic pollution is becoming increasingly concerning. Our goal goes beyond effectively treating antibiotic compounds such as oxytetracycline or ciprofloxacin—toward developing ‘green’ catalyst systems that use natural, low-cost materials and operate efficiently under sunlight.”
In the next phase, the team will continue optimizing the treatment system’s design, expanding research to other organic pollutants, and assessing the toxicity of post-treatment products to ensure environmental safety. Field trials are also being proposed to validate the material’s performance under real operating conditions.
Translated by Phuong Ha
Link to Vietnamese version
