The Innovation Team of Soil-Plant Interactions at the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) recently unveiled the mechanism by which microplastics promote the adsorption of antibiotics by biochar. The research findings provided a theoretical basis for a better comprehension of the environmental and chemical characteristics of emerging contaminants along with developing novel materials and technologies for controlling pollutants. The research findings titled "Small microplastic particles promote tetracycline and aureomycin adsorption by biochar in an aqueous solution" were published in the Journal of Environmental Management.

Compared to conventional pollutants, microplastics, antibiotics, and other emerging contaminants are extensively generated across various industrial sectors. Their associated risks remain unclear, and the development of effective control technologies presents significant challenges as a shared international scientific concern. The frequent use of organic manure, agricultural film, and wastewater irrigation in agricultural production leads to the continuous accumulation of emerging pollutants like microplastics and antibiotics in the environment. Consequently, regional environmental pollution issues arise, posing threats to the quality and safety of agricultural products, and impacting human health. Biochar, as a value solid waste byproduct, provides an environmentally friendly and low-carbon solution for addressing emerging pollutant control challenges due to its excellent structural characteristics.

The study examined the efficacy and mechanisms of diverse microplastics, varying in type and size, in adsorbing common antibiotics (tetracycline and aureomycin) using biochar. The results showed that microplastics have the capability to adsorb antibiotics and increase the adsorption capacity of biochar for antibiotics. The analysis revealed that the interaction between microplastics and biochar altered the surface characteristics of the adsorbent. Friction eroded the surface structure of the biochar, resulting in the release of dissolved organic carbon (DOC). The carrier effect caused the absorption and release of DOC by microplastics and biochar, forming a heterogeneous aggregate and reducing the concentration of small-molecule DOC in the solution. Thus an increase in particle size of the adsorbent led to enhanced adsorption of antibiotics. In addition, the study also highlighted the importance of considering the impact of microplastics in the evaluation of the adsorption effectiveness of antibiotics by biochar.

Figure 1 Mechanism of microplastics promoting antibiotic adsorption by biochar

Zhao Shuwen, a candidate for a PhD degree, and Zhang Chuchen, a master degree candidate at the IARRP, are the co-first authors of this publication. The corresponding author is Professor Zhang Qianru. This study was funded by multiple sources, including the State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, the Science & Technology Innovation Program of Chinese Academy of Agricultural Sciences, the National Natural Science Foundation of China, and the Young Scientist Exchange Program between the People’s Republic of China and the Republic of Korea of the Ministry of Science and Technology of the People’s Republic of China.

Paper link: https://doi.org/10.1016/j.jenvman.2023.119332