*Article* **Sunlight Assisted Photocatalytic Degradation of Ciprofloxacin in Water Using Fe Doped ZnO Nanoparticles for Potential Public Health Applications**

**Sourav Das 1,†, Soumen Ghosh 1,†, Ananyo Jyoti Misra 1, Ashok J. Tamhankar 1,2,‡ , Amrita Mishra 1, Cecilia Stålsby Lundborg 2,‡ and Suraj K. Tripathy 1,3,\*,‡**


Received: 25 August 2018; Accepted: 29 October 2018; Published: 1 November 2018

**Abstract:** Antibiotic residues in the aquatic environment have the potential to induce resistance in environmental bacteria, which ultimately might get transferred to pathogens making treatment of diseases difficult and poses a serious threat to public health. If antibiotic residues in the environment could be eliminated or reduced, it could contribute to minimizing antibiotic resistance. Towards this objective, water containing ciprofloxacin was treated by sunlight-assisted photocatalysis using Fedoped ZnO nanoparticles for assessing the degradation potential of this system. Parameters like pH, temperature, catalytic dosage were assessed for the optimum performance of the system. To evaluate degradation of ciprofloxacin, both spectrophotometric as well as microbiological (loss of antibiotic activity) methods were employed. 100 mg/L Fe-doped ZnO nanoparticle catalyst and sunlight intensity of 120,000–135,000 lux system gave optimum performance at pH 9 at 30 ◦C and 40 ◦C. Under these conditions spectrophotometric analysis showed complete degradation of ciprofloxacin (10 mg/L) at 210 min. Microbiological studies showed loss of antibacterial activity of the photocatalytically treated ciprofloxacin-containing water against *Staphylococcus aureus* (108 CFU) in 60 min and for *Escherichia coli* (10<sup>8</sup> CFU) in 75 min. The developed system, thus possess a potential for treatment of antibiotic contaminated waters for eliminating/reducing antibiotic residues from environment.

**Keywords:** antibiotic residues; aquatic environment; ciprofloxacin; Fe-doped ZnO nanoparticles; photocatalysis; sunlight
