Synergistic Effect of Zn Doping on the Structural, Optical, and Photocatalytic Properties of Sol–Gel Derived Spinel Ferrite for Tetracycline Photodegradation

Abstract

Pharmaceutical pollution, particularly contamination of aquatic environments, poses a significant global environmental challenge. This study introduces a novel photocatalytic approach for tetracycline removal using zinc-doped strontium magnesium aluminum ferrite (Zn_xSr_0.7−xMg_0.3Al_0.1Fe_1.9O₄, (x = 0, 0.3)) nanoparticles. We successfully engineered photocatalysts with enhanced structural and photocatalytic properties using a sophisticated sol–gel synthesis method. The zinc-doped material demonstrated remarkable improvements compared to its undoped counterpart. The key structural modifications included a reduced crystallite size (from 35.55 nm to 27.55 nm), significantly increased surface area (from 6.63 m²/g to 32.14 m²/g), and a narrowed bandgap (from 2.7 eV to 2.4 eV). These modifications directly translated into superior photocatalytic performance, with the tetracycline degradation efficiency increasing from 73.67 to 98.43%. Mechanistic investigations revealed the presence of hydroxyl radicals as the primary degradation mechanism, with first-order kinetics governing the reaction. The catalyst demonstrated exceptional stability, maintaining 93.45% degradation efficiency after five consecutive cycles. The quantum efficiency was improved by 34%, highlighting the potential of strategic metal doping for enhancing photocatalytic materials. This study provides a promising strategy for pharmaceutical pollution remediation and offers insights into advanced material design for environmental applications. Zinc-doped spinel ferrite represents a significant advancement in the development of efficient recyclable photocatalysts for water treatment.

Graphical abstract