*2.2. Preparation of Ciprofloxacin Stock Solution*

Ciprofloxacin hydrochloride stock solution (100 mg L−1) was prepared in deionized water (NaOH was used to solubilize the ciprofloxacin followed by 5 min of ultrasonication), 2 L at a time and stored in dark at 4 ◦C. Working solutions of 10 mg L−1, (in 300 mL deionized water at a time) were prepared for each photocatalysis experiment, as required.
