Solar light driven degradation of piroxicam and paracetamol by heterogeneous photocatalytic fenton system: Process optimization, mechanistic studies and toxicity assessment.

ABSTRACT

The widespread occurence of pharmaceutical pollutants seriously threatens the environment and human well-being. In the present study, zinc ferrite nanoparticles (ZnFe2O4 NPs) have been synthesized by co-precipitation method and used as photocatalyst for the degradation of two most commonly prescribed painkillers, piroxicam (PXM) and paracetamol (PCM), via heterogeneous Fenton process under the solar light. The synthesized ZnFe2O4 NPs showed a narrower band gap i.e. 1.87 eV, signifying the ability to efficiently work in visible light range. In context of photocatalytic applications, the operational conditions were optimized to achieve maximum degradation. PCM and PXM were completely degraded (100%) at the optimized photocatalytic dose (20 mg L-1), reaction time (180 min), initial drug concentration (10 mg L-1), and pH (6.0), which is close to the natural environment. The extent of mineralization as estimated by the reduction of total organic carbon (TOC) was observed to be ∼91 and 82% for PCM and PXM respectively. Kinetic studies revealed that photocatalytic degradation followed pseudo-first-order kinetics. Moreover, the ZnFe2O4 NPs retained ∼90 % of photocatalytic activity after five consecutive reaction cycles, showing remarkable reusability and stability of catalyst.