Strategic design of nitrogen and sulphur co-doped biocarbon/nickel hexacyanoferrate nanocomposite for efficient removal of ciprofloxacin and amoxicillin antibiotics from water

Abstract

The persistence, toxicity and prevalence of pharmaceutical pollutants in aquatic systems, such as Amoxicillin (AMX) and Ciprofloxacin (CIP), pose substantial environmental and health concerns. This report introduces a novel NiHCF/NSBC composite that was synthesized by combining nickel hexacyanoferrate (NiHCF) with nitrogen and sulphur co-doped biocarbon (NSBC) derived from coconut shells. The hybrid composite takes advantage of the high surface area, enhanced electronic conductivity and active sites introduced by NSBC to overcome the constraints of bare NiHCF, including the rapid recombination of charges and the restricted absorption of visible light. The composite's structural integrity, chemical interaction and synergistic properties were verified through a comprehensive characterization such as X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) techniques. The NiHCF/NSBC composite demonstrated an increased surface area (176 m²/g) and diminished photoluminescence intensity in comparison to pristine NiHCF and NSBC, indicating higher pollutant adsorption and lower charge recombination. The photocatalytic degradation results demonstrated that NiHCF and NSBC were substantially outperformed, which demonstrated remarkable degradation efficiencies of 94 % for CIP and 92 % for AMX under visible light within 90 min. The mechanism of enhanced photocatalytic activity of NiHCF/NSBC proposed through EIS, photocurrent, scavenger and PL studies. Excellent stability was verified through reusability experiments across numerous cycles. These results confirm the NiHCF/NSBC composite as a sustainable and efficient photocatalyst for the remediation of pharmaceutical pollutants, offering an environmentally favorable solution for water purification under visible light irradiation.