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<p>Amoxicillin (AMX) contamination poses serious environmental risks due to its stability and poor biodegradability. Herein, we investigate the photocatalytic degradation of AMX using carbon quantum dots (CQDs), nitrogen-doped tungsten (IV) oxide (N-WO<sub>2</sub>), and CQDs/N-WO<sub>2</sub> nanocomposite. The nanocomposite was synthesized via a facile hydrothermal-ultrasonication method and structurally characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy (SEM/TEM), and energy-dispersive X-ray spectroscopy (EDX). These analyses confirmed the successful integration of amorphous CQDs with crystalline N-WO<sub>2</sub>, uniform elemental dispersion, and the presence of characteristic functional groups and chemical states indicative of effective nanocomposite formation. Optical characterization revealed band gap energies of 2.86&#xa0;eV for CQDs, 2.56&#xa0;eV for N-WO<sub>2</sub>, and an intermediate value of 2.73&#xa0;eV for the CQDs/N-WO<sub>2</sub> nanocomposite, with favorable band alignment facilitating efficient charge separation. Under optimized conditions (pH 5.4, 15&#xa0;mg catalyst, 10&#xa0;ppm AMX, 180&#xa0;min UV–Vis irradiation), the CQDs/N-WO<sub>2</sub> nanocomposite achieved 86.61% photodegradation efficiency, significantly outperforming its individual components. Kinetic studies confirmed a pseudo-first-order degradation mechanism with the highest rate constant (R<sup>2</sup> = 0.9970), and the nanocomposite demonstrated excellent reusability over five consecutive cycles. The enhanced performance is attributed to the synergistic effects of improved light absorption, reduced charge recombination, and increased accessibility of active sites. This work presents the CQDs/N-WO<sub>2</sub> nanocomposite as a sustainable, efficient, and reusable photocatalyst for the remediation of antibiotic-contaminated wastewater.</p> Graphical Abstract <p><b>TOC Synopsis</b>: This study presents a novel CQDs/N-WO₂ nanocomposite synthesized via a combination of hydrothermal and ultrasonication methods for the efficient photocatalytic degradation of amoxicillin (AMX) in wastewater. Under optimal conditions (pH 5.4, 15&#xa0;mg catalyst, 180&#xa0;min), the composite achieves 86.61% degradation, outperforming individual components. The reusable and stable photocatalyst provides a sustainable solution for removing pharmaceutical pollutants.</p> <p></p>

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Photocatalytic Degradation of Amoxicillin via Carbon Quantum Dots Coupled with Nitrogen-Doped Tungsten (IV) Oxide: Chemical Method for Reclamation of Drug-Contaminated Wastewater

  • 期刊论文

  • 发表日期：

    2026年5月5日

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  • Irum Shah,
  • Farman Ali,
  • Nisar Ali,
  • Maaz Ullah,
  • Mohammad M. Al-Hinaai,
  • Mohammad Albahri,
  • Amir Said

摘要

Amoxicillin (AMX) contamination poses serious environmental risks due to its stability and poor biodegradability. Herein, we investigate the photocatalytic degradation of AMX using carbon quantum dots (CQDs), nitrogen-doped tungsten (IV) oxide (N-WO2), and CQDs/N-WO2 nanocomposite. The nanocomposite was synthesized via a facile hydrothermal-ultrasonication method and structurally characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy (SEM/TEM), and energy-dispersive X-ray spectroscopy (EDX). These analyses confirmed the successful integration of amorphous CQDs with crystalline N-WO2, uniform elemental dispersion, and the presence of characteristic functional groups and chemical states indicative of effective nanocomposite formation. Optical characterization revealed band gap energies of 2.86 eV for CQDs, 2.56 eV for N-WO2, and an intermediate value of 2.73 eV for the CQDs/N-WO2 nanocomposite, with favorable band alignment facilitating efficient charge separation. Under optimized conditions (pH 5.4, 15 mg catalyst, 10 ppm AMX, 180 min UV–Vis irradiation), the CQDs/N-WO2 nanocomposite achieved 86.61% photodegradation efficiency, significantly outperforming its individual components. Kinetic studies confirmed a pseudo-first-order degradation mechanism with the highest rate constant (R2 = 0.9970), and the nanocomposite demonstrated excellent reusability over five consecutive cycles. The enhanced performance is attributed to the synergistic effects of improved light absorption, reduced charge recombination, and increased accessibility of active sites. This work presents the CQDs/N-WO2 nanocomposite as a sustainable, efficient, and reusable photocatalyst for the remediation of antibiotic-contaminated wastewater.

Graphical Abstract

TOC Synopsis: This study presents a novel CQDs/N-WO₂ nanocomposite synthesized via a combination of hydrothermal and ultrasonication methods for the efficient photocatalytic degradation of amoxicillin (AMX) in wastewater. Under optimal conditions (pH 5.4, 15 mg catalyst, 180 min), the composite achieves 86.61% degradation, outperforming individual components. The reusable and stable photocatalyst provides a sustainable solution for removing pharmaceutical pollutants.