Sensitive determination of multiclass veterinary drug residues in aquaculture water requires efficient sample preparation capable of handling trace contaminants while minimizing sample consumption and manual operation. Here, a periodic magnetic actuation-assisted microfluidic enrichment platform was integrated online with HPLC–MS/MS for the determination of quinolones, sulfonamides, tetracyclines, and malachite green. Fe₃O₄@GO was magnetically confined within a multi-serpentine microchannel, and the effects of channel geometry and magnetic operating conditions on sorbent retention and flow-through capture were systematically evaluated. The multi-serpentine configuration limited Fe₃O₄@GO loss to 3.82% after ten operating cycles, while 200 mT and 10 Hz provided effective magnetic confinement and capture performance. In the final workflow, 50 μL of sample was loaded at 5 μL min⁻¹ for 10 min, followed by mobile-phase-mediated release and transfer through an online C18 cleanup/trapping column for chromatographic analysis. The method achieved limits of detection of 0.02–0.17 μg L⁻¹, limits of quantification of 0.07–0.53 μg L⁻¹, recoveries of 79.84–97.66% in spiked real aquaculture water, and RSDs of 3.41–7.24%. These results demonstrate a low-volume and integrated sample-preparation strategy for multiclass veterinary drug determination in aquaculture-water matrices.
Titanium dioxide (TiO2) photocatalysis is a promising advanced oxidation method for water treatment, but its reliance on UV irradiation limits practical solar-driven applications. This study addresses this limitation by synthesizing lignin-based carbon quantum dots (L–CQDs) from kraft lignin and combining them with anatase TiO2 to create a visible-light-active hybrid photocatalyst. L–CQDs/TiO₂ composites with 1–4 wt.% L–CQD loadings were prepared, thoroughly characterized, and evaluated for photocatalytic performance under simulated visible light (400–700 nm). The optimized 3 wt.% L–CQDs/TiO2 hybrid achieved simultaneous degradation of sulfamethoxazole (SMX) and ibuprofen (IBU) with removal efficiencies of 98.6% and 79.7%, respectively, after 90 min – representing 118-fold and 5-fold increases in pseudo-first-order rate constants compared to bare TiO2. Radical scavenging experiments revealed a dual degradation mechanism: SMX was degraded mainly by superoxide radicals in the bulk solution, while IBU was degraded at the photocatalyst surface via photogenerated holes, with hydroxyl radicals playing a negligible role. Density functional theory calculations of frontier molecular orbital energies supported this mechanistic distinction. Matrix effects in tap water selectively suppressed IBU degradation due to competing hole consumption by CO₃²⁻ and Cl⁻, while SMX degradation remained unaffected. These findings demonstrate that L–CQDs act as a sustainable photosensitizer, shifting TiO2 activity into the visible range through a charge-transfer mechanism rather than direct band gap modification, enabling efficient multi-pollutant removal under solar-relevant irradiation.
Per- and polyfluoroalkyl substances (PFAS) are persistent contaminants widely detected in stormwater, yet cost-effective sorbents performing across structurally diverse PFAS remain limited. We report a cationic polyacrylonitrile–cetyltrimethylammonium chloride (PAN–CTAC) electrospun nanofibrous membrane fabricated by a single electrospinning–spraying step. In batch experiments, the PAN–CTAC membrane pieces achieved >95% removal of all ten tested PFAS, including short-chain, long-chain, and emerging alternatives, each at an initial concentration of 10 µg L−1. Kinetics followed pseudo-second-order behavior (R2 > 0.98). Among the four mixture-level isotherm models evaluated, the Sips model yielded the highest R2 (0.969) and the lowest RMSE (122.2 µg g−1), corresponding to an apparent total adsorption capacity of 2068.5 µg g−1 for the fixed ten-PFAS mixture. Removal exceeded 95% across pH 3–11 under elevated ionic strength and natural organic matter and reached ∼85–100% in authentic stormwater at 1–10 µg L−1. FT-IR, XPS, and XRD confirmed permanent quaternary ammonium groups within a porous fiber architecture. XDLVO analysis showed that the positively charged PAN–CTAC surface maintains attractive electrostatic double-layer interactions toward anionic PFAS, whereas pristine PAN imposes a repulsive barrier. Capture occurs through electrostatic ion-pairing and hydrophobic stabilization. After three regeneration cycles, most PFAS retained removal efficiencies of at least approximately 80%, whereas PFOS removal decreased to approximately 70%.
Widespread heavy metal contamination in water and soil causes severe environmental and life risks. Recently, biochar has demonstrated excellent adsorption performances in removal of various organic and inorganic pollutants. In this study, biochar derived from Prosopis juliflora was prepared and utilized for Cr(VI) removal. Batch adsorption experiments were evaluated for optimizing the chromium removal conditions. Isotherm study revealed Sips isotherm model demonstrated the best fit confirming heterogeneous monolayer adsorption with maximum adsorption capacity of 100.95 mg g−1. Moreover, adsorption kinetics revealed the best described model fits for pseudo first order kinetics indicating physisorption mechanism. Thermodynamic study confirmed the spontaneous and exothermic nature of Cr(VI) adsorption. Machine learning predictive modelling enables the removal performances of pollutants. Particularly, tree-based ensemble models preferred due to its robustness and superiority in predictive performances. Therefore, the current study integrates six machine learning models to predict the Cr(VI) removal efficiency onto PJ-BC adsorbent. Among ML models, CatBoost demonstrated the best predictive performance with highest R2 of 0.988 and least RMSE of 2.648. This study also incorporated interpretable ML framework including SHapley Additive exPlanations and Partial Dependence Plots for elucidating the feature importance of input variables. Through experimental and machine learning modelling with Prosopis juliflora biochar for chromium removal, this study contributes towards the development of sustainable and data-driven wastewater treatment strategies for Cr(VI) contaminated effluents.
Copper nanoclusters stabilized by thiol ligands have been introduced as a new ultra-small nanomaterial with specific physicochemical properties such as photoluminescence, surface activity, and biocompatibility. Moreover, the surface chemistry of copper nanoclusters enables the attachment of drugs, thus opening the possibility for the use of these materials in drug delivery systems. The conventional copper nanoclusters have specific energy levels because of their molecular dimension (<2 nm), which makes them useful in various applications. Among the copper nanoclusters stabilizers, thiols are highly active in the stabilization of copper nanoclusters because of their high binding affinity for the formation of stable copper-sulfur bonds. The stabilization of copper nanoclusters by thiols not only makes them stable against oxidation and agglomeration but also enables the attachment of functional groups for specific uses. This review aims to extensively discuss the synthesis routes, structural properties, and multi-functional uses of copper nanoclusters stabilized by thiols. The review critically discusses the recent developments in the synthesis and efficiency of copper nanoclusters in various sectors. Moreover, the review discusses the challenges faced in the synthesis of copper nanoclusters such as instability in the presence of oxidizing agents, low photoluminescence quantum yields, and scaling-up challenges.
