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Abstract:
This study explores an efficient decontamination strategy using platinum-coated polystyrene rough-particles as a micron-sized catalyst system for decomposing methylene blue (MB), a common organic pollutant. The synthesized nanomaterials were comprehensively characterized using Nanoparticle Tracking Analysis (NTA), Dynamic Light Scattering (DLS), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM), confirming their morphology, size distribution, and surface properties. The decontamination was performed at the air-water interface through an interface trapping method, with enhanced mixing achieved under a controlled flow environment. The experiments were conducted with a circulation speed of 50 RPM, corresponding to a Reynolds number (NR) of 1686 and a high particle packing fraction of 0.8. Under these operating conditions, complete degradation of MB was achieved within 30 min, significantly faster than the 75 min required for degradation in the bulk phase. The reaction kinetics were analyzed and found to follow the Langmuir–Hinshelwood model, with an estimated rate constant of 0.018 min−1, indicating efficient surface-mediated catalytic activity. Furthermore, an Artificial Neural Network (ANN) model was developed to validate and predict the degradation kinetics, showing a Root Mean Square Error (RMSE) of 5.5 and a high correlation coefficient (R2) of 0.9656, confirming the reliability of the predictive model. This interface-assisted, catalyst-based degradation approach demonstrates a promising, reusable, cost-effective, and environmentally friendly solution for advanced wastewater treatment applications.

Keywords:
Methylene blue, Pt nanoparticles, Air-water interface, Wastewater, ANN modeling, Removal efficiency

Abstract:
The increasing groundwater pollution resulting from industrial dyes and pharmaceutical products, which come from various sources, requires urgent attention to implement effective remediation measures. We demonstrate that the rough particles studded with platinum (Pt) nanoparticles can be fabricated at room temperature straightforwardly and in a single step. These rough particles displayed a good catalytic power (100% removal efficiency) against a model industrial dye (methylene blue) and pharmaceutical residue (tetracycline) within a reasonable time scale. Characterization techniques such as X-ray diffraction (XRD), atomic force microscopy (AFM), and field emission scanning electron microscopy (FESEM) confirmed the uniform deposition of Pt nanoparticles on the surface of polystyrene particles, forming dense islands and the roughened surface. Further, we investigated the influence of particle size, concentration, and contact patterns on the performance of rough catalytic particles. The semi-batch conditions favoured the complete decomposition of tetracycline within 40 min, but the batch-wise operation offered a good contacting pattern for methylene blue, yielding a maximal output within 10 min. The kinetics of the heterogeneous catalytic process modelled by Langmuir-Hinshelwood kinetics (r = kKC/1 + KC) predicts that the given methylene blue decomposition reaction induced by the rough particles follows the pseudo-first-order kinetics. The rate constants for the reaction catalyzed by 0.6 and 1.0 m-sized rough particles are 0.048 and 0.032 min, respectively. Furthermore, we established the proof-of-concept using magnetically responsive nanoparticles for real-time applications, including decontamination and recovery of catalyst particles via an externally applied magnetic field in one cycle. Our proposed method helps achieve a near-100% degrading efficiency within 10 to 40 min at minimal catalytic particle concentration, i.e., 200 ppm. Since we can turn the rough particles into super-paramagnetic, we can recover and reuse them for several wastewater treatment cycles without incurring running costs.

Keywords:
Polystyrene (PS), Iron Oxide (IO), Plat- inum nanoparticles, Rough particles, Magnetically- responsive nanoparticles, Methylene blue, Tetracy- cline, Environmental remediation