Photocatalytic degradation of Methylene Blue dye using CaFe2O4/SWCNT Nanocomposite

Abstract

Introduction: The discharge of dye-containing wastewater from textile and related industries poses serious environmental concerns due to the toxicity, persistence, and non-biodegradable nature of synthetic dyes. Among these pollutants, methylene blue (MB) is widely used and frequently detected in industrial effluents. Photocatalysis has emerged as an effective and eco-friendly approach for dye degradation. In this context, ferrite/carbon nanocomposites have gained attention because of their enhanced charge separation and catalytic efficiency.

Objectives: This study aimed to synthesize a CaFe₂O₄/SWCNT nanocomposite and evaluate its photocatalytic performance for the degradation of methylene blue dye under UV irradiation

Methods: The CaFe₂O₄/SWCNT nanocomposite was synthesized by a hydrothermal-assisted method followed by calcination. The prepared material was characterized using UV–Visible spectroscopy and FTIR analysis to examine optical properties and functional groups. Photocatalytic degradation experiments were carried out using 10 mg of catalyst dispersed in 100 mL of 10 ppm MB solution under UV light irradiation. The degradation process was monitored at 662 nm using UV–Visible spectroscopy. Degradation efficiency and pseudo-first-order kinetic behavior were determined.

Results: UV–Visible analysis showed enhanced light absorption and broadened spectral response for the CaFe₂O₄/SWCNT nanocomposite compared with pristine SWCNT. FTIR spectra confirmed the presence of characteristic Fe–O/Ca–O bonds and carbon functional groups, indicating successful composite formation. The photocatalyst achieved 79.9% degradation of MB within 120 min, while only 8.9% degradation was observed under light-only conditions. The degradation followed pseudo-first-order kinetics with a rate constant of 0.01005 min⁻¹, which was significantly higher than the control (0.00078 min⁻¹).

Conclusion: The CaFe₂O₄/SWCNT nanocomposite exhibited excellent photocatalytic activity toward methylene blue degradation due to improved light absorption, efficient charge separation, and enhanced radical generation. The results demonstrate that this material is a promising low-cost photocatalyst for wastewater treatment and environmental remediation applications.