Issue 20, 2025

Innovative CuBTC/g-C3N4 materials for tetracycline mitigation: adsorption, photocatalysis, and mechanistic perspectives

Abstract

The widespread accumulation of antibiotic pollutants in water sources calls for advanced and efficient remediation strategies to curb environmental contamination. In this study, a CuBTC (copper benzene-1,3,5-tricarboxylate) with g-C3N4 heterojunction photocatalyst was synthesized via a hydrothermal approach in varying ratios (1 : 1, 1 : 3, and 3 : 1) and comprehensively characterized using XRD, FESEM, EDS, HRTEM, EIS, UV-DRS, PL, TGA, FTIR, XPS, and BET measurements, confirming the composite's crystallinity, morphology, elemental composition, charge transport properties, optical behavior, stability, and porosity. Among the tested compositions, the 3 : 1 CuBTC/g-C3N4 composite exhibited the highest efficiency, achieving an impressive 97.4% degradation of 25 ppm tetracycline (TC) within just 60 minutes under UV illumination, with a remarkable rate constant of 0.02098 min−1. Stability assessments confirmed its excellent reusability over six consecutive cycles, with only a slight decline in performance to 82.7%. The adsorption behaviour of the composite was analyzed using six isotherm models—Langmuir, Freundlich, Halsey, Harkins–Jura, Temkin, and Dubinin–Radushkevich—along with five kinetic models, including pseudo-first-order, pseudo-second-order, intraparticle diffusion, Elovich, and liquid film models. Adsorption followed the Langmuir isotherm (R2 = 0.992) and pseudo-second-order kinetics (R2 = 0.968), while photocatalytic degradation aligned with pseudo-second-order kinetics (R2 = 0.993). Mechanistic studies identified superoxide radicals as the primary reactive species, supported by hydroxyl radicals, electrons, and holes in the degradation pathway. Mineralization studies revealed significant reductions in TOC (67.8%) and COD (68.6%), while LC-MS analysis provided a comprehensive degradation pathway, illustrating the breakdown of TC into intermediates through ring-opening and oxidative transformations. Thermodynamic assessments indicated that the degradation process was exothermic and spontaneous. ΔG, ΔH and ΔS values were found to be 92.7 J mol−1, −63.84 kJ mol−1, and −0.214 kJ mol−1 K−1 respectively.

Graphical abstract: Innovative CuBTC/g-C3N4 materials for tetracycline mitigation: adsorption, photocatalysis, and mechanistic perspectives

Supplementary files

Article information

Article type
Paper
Submitted
10 Feb 2025
Accepted
08 Apr 2025
First published
06 May 2025
This article is Open Access
Creative Commons BY license

New J. Chem., 2025,49, 8454-8471

Innovative CuBTC/g-C3N4 materials for tetracycline mitigation: adsorption, photocatalysis, and mechanistic perspectives

P. Sethi, S. Basu and S. Barman, New J. Chem., 2025, 49, 8454 DOI: 10.1039/D5NJ00556F

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