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<p>The escalating presence of pharmaceutical contaminants, particularly antibiotics, in aquatic environments has emerged as a global threat due to their persistence, ecological toxicity, and role in fostering antibiotic resistance. Despite extensive efforts, conventional treatment methods fall short in achieving complete degradation and mineralization of these pollutants. This study addresses this critical challenge by developing a visible light-responsive photocatalyst composed of SnO₂ nanoparticles integrated with reduced graphene oxide (rGO). While prior studies have explored SnO₂-based photocatalysts, there is a noticeable gap in using SnO₂/rGO composites for the simultaneous degradation of multiple antibiotics under natural sunlight. Herein, SnO₂, rGO, and SnO₂/rGO composites (SG-I to SG-III) were synthesized via co-precipitation and hydrothermal methods and analyzed using comprehensive physicochemical and spectroscopic characterization techniques. The optimized SG-I (80% SnO₂/20% rGO) nanocomposite exhibited superior charge separation, reduced recombination, enhanced visible light absorption, and excellent hydrophilicity, with a contact angle of just 1.7°, thereby promoting efficient interaction with aqueous pollutants. Photocatalytic experiments revealed that SG-I achieved significant degradation efficiencies of 92%, 80%, and 67% against 45&#xa0;ppm of nitrofurantoin, sulfamethazine, and sulfadiazine, respectively, following first-order kinetics. Density functional theory (DFT)-based quantum chemical reactivity analysis was also performed for nitrofurantoin and sulfamethazine to elucidate their molecular reactivity, charge distribution, and preferred radical attack sites. Moreover, total organic carbon (TOC) analysis confirmed high mineralization rates, particularly for nitrofurantoin (94.9%). The improved performance is attributed to the formation of a Z scheme heterojunction, which facilitates efficient charge transfer and the generation of reactive oxygen species (ROS). This work not only offers a sustainable route for antibiotic degradation under sunlight but also shifts the current paradigm in photocatalytic wastewater treatment by demonstrating the viability of SnO₂/rGO composites as high-performance, reusable photocatalysts.</p>

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Sunlight-driven photocatalytic degradation of antibiotics using SnO₂/rGO heterojunction: experimental and theoretical study

  • 期刊论文

  • 发表日期：

    2026年2月6日

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  • K. Kaviya,
  • M. Selva Ganapathy,
  • S. Jayapandi,
  • M. Tamilelakkiya

摘要

The escalating presence of pharmaceutical contaminants, particularly antibiotics, in aquatic environments has emerged as a global threat due to their persistence, ecological toxicity, and role in fostering antibiotic resistance. Despite extensive efforts, conventional treatment methods fall short in achieving complete degradation and mineralization of these pollutants. This study addresses this critical challenge by developing a visible light-responsive photocatalyst composed of SnO₂ nanoparticles integrated with reduced graphene oxide (rGO). While prior studies have explored SnO₂-based photocatalysts, there is a noticeable gap in using SnO₂/rGO composites for the simultaneous degradation of multiple antibiotics under natural sunlight. Herein, SnO₂, rGO, and SnO₂/rGO composites (SG-I to SG-III) were synthesized via co-precipitation and hydrothermal methods and analyzed using comprehensive physicochemical and spectroscopic characterization techniques. The optimized SG-I (80% SnO₂/20% rGO) nanocomposite exhibited superior charge separation, reduced recombination, enhanced visible light absorption, and excellent hydrophilicity, with a contact angle of just 1.7°, thereby promoting efficient interaction with aqueous pollutants. Photocatalytic experiments revealed that SG-I achieved significant degradation efficiencies of 92%, 80%, and 67% against 45 ppm of nitrofurantoin, sulfamethazine, and sulfadiazine, respectively, following first-order kinetics. Density functional theory (DFT)-based quantum chemical reactivity analysis was also performed for nitrofurantoin and sulfamethazine to elucidate their molecular reactivity, charge distribution, and preferred radical attack sites. Moreover, total organic carbon (TOC) analysis confirmed high mineralization rates, particularly for nitrofurantoin (94.9%). The improved performance is attributed to the formation of a Z scheme heterojunction, which facilitates efficient charge transfer and the generation of reactive oxygen species (ROS). This work not only offers a sustainable route for antibiotic degradation under sunlight but also shifts the current paradigm in photocatalytic wastewater treatment by demonstrating the viability of SnO₂/rGO composites as high-performance, reusable photocatalysts.