Morphology tuning of g-C3N4 for Rhodamine B and mixed-dye system degradation via visible-light photocatalysis
摘要
The degradation of persistent organic pollutants present in wastewater remains a significant environmental challenge. Photocatalysis is considered one of the most suitable advanced oxidation processes for addressing this problem. In this context, g-C3N4 represents a promising option due to its low cost, low toxicity, and metal-free nature. The objective of this work was to synthesize and characterize three morphologies of g-C3N4—lamellar, microrods, and nanotubes—and to evaluate their photocatalytic performance in the degradation of the Rhodamine B dye. These morphologies were obtained by chemical reflux, hydrothermal treatment, and self-assembly. XRD, FTIR, STEM, BET, UV–Vis, PL, and XPS were employed to characterize the samples. Photocatalytic activity was evaluated using 50 mg of g-C3N4 in 50 mL of a 10 ppm Rhodamine B solution under visible light provided by a commercial 20 W lamp. The g-C3N4 nanotube morphology showed the best photocatalytic performance, achieving 85% degradation of Rhodamine B after 80 min of reaction. The pseudo-first-order rate constant (k = 2.15 ± 0.29 × 10−2 min−1) was 4.48 times higher than that of bulk g-C3N4, confirming the influence of the tubular morphology on the degradation efficiency. The g-C3N4 nanotubes exhibited high performance for the simultaneous degradation of methylene blue and methyl orange in mixed-dye systems. Stability tests over six consecutive cycles (660 min) without intermediate washing resulted in a 14% efficiency loss, confirming the photocatalyst´s durability in complex aqueous matrices. g-C3N4 with a nanotube morphology is highly promising for pollutant degradation.