Enhanced Photocatalytic Degradation of Tetracycline by Mg, Co, Cu, and Fe-Doped Versus Undoped Nickel Aluminate: Comparative Mechanism and Efficiency Study

The degradation of tetracycline, a persistent antibiotic pollutant, was systematically investigated using Mg-doped nickel aluminate(90.19%), Co-doped nickel aluminate (74.35%), Cu-doped nickel aluminate (81.63%), Fe-doped nickel aluminate (64.28%), and undoped nickel aluminate (62.68%) photocatalysts. In each experiment, 12.5 mg of tetracycline and 25 mg of the corresponding catalyst were added to 100 mL of distilled water, and the reaction was monitored for 120 minutes under visible light. SEM analysis revealed distinct dopant-dependent morphologies, ranging from agglomerated particles to well-defined layered structures, which influence surface adsorption and catalytic activity. The particle size of all nickel aluminate catalysts was found to range from 50 to 180nm. Photoluminescence (PL) spectra showed that Mg-doped nickel aluminate exhibited lower PL intensity than Cu- and Co-doped samples, indicating more efficient suppression of electron-hole recombination. The structural and optical characteristics of the corresponding nickel aluminates were directly correlated with the observed enhanced tetracycline removal rates, particularly for the doped catalysts. Kinetic studies confirmed pseudo-first-order behavior, and the degradation efficiency and the resulting mechanistic pathway were comprehensively evaluated for Tetracycline degradation. Overall, the combined evidence demonstrates that metal doping substantially improves the photocatalytic performance of nickel aluminate, primarily through optimized surface morphology and more efficient charge-carrier dynamics, offering a promising approach for tetracycline remediation in contaminated water systems.