With the acceleration of industrialisation, aquatic pollution has emerged as a global environmental challenge. Recent environmental monitoring studies have revealed increasing diversity of detected contaminants in water systems, including pesticide residues[1], personal care products [2], industrial dyes [3], and pharmaceutical active compounds [4]. Among these emerging pollutants, non-steroidal anti-inflammatory drugs (NSAIDs) have raised particular concerns due to their widespread application in medical and agricultural sectors, coupled with their persistent environmental accumulation [5,6]. Scientific investigations confirm that NSAIDs, as typical trace organic contaminants, are ubiquitously detected in surface water, groundwater, and soil matrices [7]. For example, diclofenac sodium (DS) is widely recognized as the most ecotoxic member of the NSAID family. Due to its environmental persistence and potential for bioaccumulation, it poses a serious threat to aquatic ecosystems[8,9]. At present, the European Union has included DS in the environmental monitoring watch list in the Water Framework Directive[10]. This urgent situation underscores the need to develop new functional materials that exhibit high selectivity and superior adsorption capacity for the effective detection of non-steroidal anti-inflammatory drug residues in aquatic systems.

Currently, various technologies have been developed for detecting NSAIDs contaminants from aquatic systems, including membrane filtration detection [11,12], adsorption detection [13], and biological detection [14]. Among these approaches, adsorption technology has gained extensive application in environmental detection due to its operational simplicity, high detection efficiency, cost-effectiveness, and absence of byproducts [15]. Research findings demonstrate that advanced adsorbents such as activated carbon [16], porous adsorption rods [17], metal-organic frameworks (MOFs) [5] and carbon nanotubes [18] have been successfully employed for NSAIDs removal in aquatic environments. Nevertheless, current materials still face technical challenges, including material design difficulties and difficulty in separation within complex aqueous matrices[13,19]. Consequently, the development of novel adsorbents with high adsorption capacity, excellent reusability, high selectivity and efficient recovery characteristics remains a crucial research focus in water environment monitoring.

Covalent organic framework materials (COFs)[[20], [21], [22]] are a new type of crystalline porous material, usually composed of light elements such as C, N, O, and H connected by organic structural units through covalent bonds, and eventually forming three-dimensional or two-dimensional network configurations. COFs possess characteristics such as low density[23], inherent high porosity, high surface area, and structurally ordered and adjustable[24]. In recent years, COFs have attracted extensive attention from researchers in many fields[[25], [26], [27]], such as photocatalysis, gas adsorption, water pollution treatment[28], etc. Microporous organic networks (MONs) constructed through dynamic covalent chemistry or strong covalent interaction, through reasonable monomer design and reversible reaction control, have achieved a tailor-made pore structure. These materials possess unique characteristics, including narrow-distributed micropores, ultra-high specific surface area and rich modifiable surface functions. Recent studies have highlighted the outstanding performance of MONs in water environment monitoring. For instance, Hu’s team [29] designed a cationic MON composite material for the ultra-sensitive detection of non-steroidal anti-inflammatory drugs in water and milk matrices. As emerging porous materials, COFs and MONs exhibit a range of shared characteristics while also displaying distinct complementary features. In comparison to COFs, MONs generally demonstrate superior chemical stability, well-defined microporosity, a richer variety of surface functional groups, and enhanced adsorption capacity. However, the inherent limitations of each material type often lead to suboptimal performance when they are employed individually in adsorption-related applications. Consequently, it becomes essential to integrate the advantageous properties of both COFs and MONs through rational material design strategies, particularly to achieve improved selectivity, sensitivity, and efficiency in detection processes.

In recent years, some researchers have prepared magnetic MOF/COF adsorbent materials by combining MOF with COF. For example, the Ma’s team[30] designed a magnetic MOF@COF hybrid material for dye adsorption removal. However, there are relatively fewer studies focusing on MON/COF adsorbent materials, particularly regarding the application of magnetic MON/COF adsorbents for drug trace detection from water, which has not yet been reported.

Based on our previous research[31], in this study, two novel composite adsorbents, MMON-Br@COF and MMON-I@COF, were synthesized by integrating two magnetic MONs with imine-containing COFs respectively via a Schiff base reaction. The composite materials were systematically characterized and analyzed by using advanced characterization techniques such as XRD, FT-IR, XPS, and EDS etc. The adsorption performance of NSAIDs was comprehensively evaluated using the obtained materials. The adsorption behavior of the adsorbent on DS was theoretically studied by using adsorption kinetics and isotherm analysis. In addition, the effects of adsorption time, desorption solution, adsorbent dosage, pH value, interfering ions and the reusability of the adsorbent on the adsorption process were investigated by HPLC. A novel MSPE-HPLC detection method was established based on MMON-Br@COF, and the adsorption mechanism was clarified through experiments. Finally, the trace detection performance of MMON-Br@COF and MMON-I@COF for NSAIDs was tested in the actual water environment.