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<p>Gold nanoparticle decorated multiwalled carbon nanotubes (GNP-oMwCNT) were synthesized by anchoring ~ 16&#xa0;nm spherical gold nanoparticles onto oxidized multiwalled carbon nanotubes functionalized using a concentrated H<sub>2</sub>SO<sub>4</sub>/HNO<sub>3</sub> mixture (3:1 v/v). The light-induced catalytic performance of gold nanoparticle (GNP) nanosuspension, oxidized MwCNT (oMwCNT), and the hybrid GNP-oMwCNT nanocomposite was evaluated through UV assisted degradation of crystal violet (CV) dye. Among the tested materials, the GNP-oMwCNT nanocomposite exhibited significantly enhanced removal efficiency, achieving 73% removal of CV dye (20&#xa0;mg/L) under UV irradiation, whereas for GNP and oMwCNT alone, achieved removal efficiency was in the range 20–25%. Kinetic analysis indicated that dye removal by GNP nanosuspension and oMwCNT followed the pseudo-second order model (R<sup>2</sup>&gt;0.94), suggesting surface-controlled adsorption. In contrast, the GNP-oMwCNT nanocomposite showed comparable R<sup>2</sup> values for both pseudo first-order and pseudo second-order models, a transition toward a coupled adsorption-catalysis mechanism. The apparent equilibrium adsorption capacities (q<sub>e</sub>) estimated from the kinetic models were ~ 32.7, 27, and 520&#xa0;mg/g for the GNP nanosuspension, oMwCNT, and the GNP-oMwCNT nanocomposite, respectively, showing good agreement with experimental results. The superior performance of the nanocomposite arises from the synergistic interaction between GNP and oMwCNT under UV irradiation. The oMwCNT provides efficient adsorption sites through their functional groups and mixed porosity, while the presence of GNP enhances interfacial charge transfer and electronic interaction at the composite interface, promoting light driven ROS generation and supporting dye degradation. These findings are supported by radical scavenger experiments, which indicate that reactive oxygen species (ROS) contribute to the degradation process, with hydroxyl radicals (·OH) acting as the primary oxidants, photo-excited charge carriers playing a secondary role, and superoxide radicals (O<sub>2</sub>·<sup>−</sup>) contributing to a lesser extent in GNP-oMwCNT nanocomposite.</p>

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Kinetics and mechanistic insights into UV-assisted degradation of crystal violet dye using gold nanoparticle-oMwCNT nanocomposites

  • 期刊论文

  • 发表日期：

    2026年5月23日

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  • Chetan Pant,
  • Puja Goel

摘要

Gold nanoparticle decorated multiwalled carbon nanotubes (GNP-oMwCNT) were synthesized by anchoring ~ 16 nm spherical gold nanoparticles onto oxidized multiwalled carbon nanotubes functionalized using a concentrated H2SO4/HNO3 mixture (3:1 v/v). The light-induced catalytic performance of gold nanoparticle (GNP) nanosuspension, oxidized MwCNT (oMwCNT), and the hybrid GNP-oMwCNT nanocomposite was evaluated through UV assisted degradation of crystal violet (CV) dye. Among the tested materials, the GNP-oMwCNT nanocomposite exhibited significantly enhanced removal efficiency, achieving 73% removal of CV dye (20 mg/L) under UV irradiation, whereas for GNP and oMwCNT alone, achieved removal efficiency was in the range 20–25%. Kinetic analysis indicated that dye removal by GNP nanosuspension and oMwCNT followed the pseudo-second order model (R2>0.94), suggesting surface-controlled adsorption. In contrast, the GNP-oMwCNT nanocomposite showed comparable R2 values for both pseudo first-order and pseudo second-order models, a transition toward a coupled adsorption-catalysis mechanism. The apparent equilibrium adsorption capacities (qe) estimated from the kinetic models were ~ 32.7, 27, and 520 mg/g for the GNP nanosuspension, oMwCNT, and the GNP-oMwCNT nanocomposite, respectively, showing good agreement with experimental results. The superior performance of the nanocomposite arises from the synergistic interaction between GNP and oMwCNT under UV irradiation. The oMwCNT provides efficient adsorption sites through their functional groups and mixed porosity, while the presence of GNP enhances interfacial charge transfer and electronic interaction at the composite interface, promoting light driven ROS generation and supporting dye degradation. These findings are supported by radical scavenger experiments, which indicate that reactive oxygen species (ROS) contribute to the degradation process, with hydroxyl radicals (·OH) acting as the primary oxidants, photo-excited charge carriers playing a secondary role, and superoxide radicals (O2·−) contributing to a lesser extent in GNP-oMwCNT nanocomposite.