Enhanced visible-light-driven photocatalytic degradation of methylene blue and ciprofloxacin using magnetic NiFe2O4@ZIF 67

Abstract

Designing metal organic framework (MOF)-based stable heterostructures remains a challenging task for material scientists. Herein, a magnetic photocatalyst, designated 30NFZ67, was synthesized using a simple and green method by combining ZIF 67 and NiFe₂O₄ at room temperature. The fabrication of a hybrid MOF material was characterized using various techniques, such as IR spectroscopy, PXRD, XPS, TGA, FESEM, and TEM, which revealed the successful formation of a heterostructure. Under sunlight, the photocatalyst effectively degraded two major organic pollutants methylene blue (MB) dye (∼98%) and ciprofloxacin (CIP) antibiotic (∼88%) via a multistep charge transfer mechanism. This process is primarily driven by solar energy, highlighting its potential for sustainable environmental remediation. Trapping experiments identified hydroxyl radicals (˙OH) and superoxide radicals (˙O₂⁻) as the dominant reactive species in the degradation pathway. The degradation efficiency significantly increased with catalyst dosage, increasing from 72% to 98% for methylene blue (MB) as the dosage increased from 2.5 mg to 10 mg. Similarly, for ciprofloxacin (CIP), the efficiency improved from 53% to 88% when the catalyst dose was increased from 5 to 10 mg within 60 minutes. The photocatalyst exhibited excellent structural stability over 20 consecutive degradation cycles. Additionally, a detailed analysis of the degradation mechanism and kinetics studies provided valuable insights into the heterojunction design for developing high-performance magnetic photocatalysts for wastewater treatment. In alignment with the United Nations Sustainable Development Goal 6 (clean water and sanitation), this work addresses the urgent challenge of emerging organic pollutants in wastewater. Hence, this work highlights the potential of a sustainable and recyclable photocatalyst for wastewater treatment.