Fabrication of chitosan-hydroxyapatite nano-adsorbent for removal of norfloxacin from water: Isotherm and kinetic studies

• Main Authors: Nayak, Arunima, Bhushan, Brij, Kotnala, Shreya
• Format: Conference Proceeding
• Language: English
• Subjects: Adsorption; Hydroxyapatite; Isotherm; Kinetics; Nanocomposite; Norfloxacin
• ISSN: 2214-7853; 2214-7853
• DOI: 10.1016/j.matpr.2021.07.356

Norfloxacin (NOR) is a widely used antibiotic but because of its poor absorption, is mainly excreted out. This accounts for its presence in municipal and domestic wastewater in significant concentrations. It is classified as an emerging pollutant whose presence in water bodies can lead to serious environmental disorders. Adsorption is widely recognized as a cleaner, environmentally friendly and cost-effective remediation option. Choice of the adsorbent dictates the efficiency of the treatment process. With an aim to ensure the sustainability of the treatment process and to enhance the physico-chemical features of the adsorbent, a biocompatible nano-composite (HAP@CT) was fabricated from hydroxyapatite (HAP) and chitosan (CT). The removal performance of NOR from simulated water was studied via batch adsorption experiments onto the fabricated adsorbent. Optimum parameters with respect to pH, contact time, temperature, adsorbate concentration and adsorbent dosage were determined for determining the conditions for achieving higher NOR removal rates. Isotherm data was modelled using Langmuir and Freundlich while kinetic data was applied to pseudo-first order and second order models. Results revealed that norfloxacin showed low binding affinity to HAP@CT; with adsorption capacity increasing with increased adsorbent dosage. Maximum adsorption (92%) occurred at a dosage of 0.5 g/L and at a pH of 7. Kinetic studies revealed an equilibrium time of 120 mins that brought about enhanced adsorption for NOR. Adsorption data fitted well to Langmuir model (Langmuir adsorption capacity determined was 625 mg/g) while pseudo-first order kinetics best explained the kinetic data. Mechanism of binding of the adsorbate was determined to be physisorption as evident from spectroscopic data and isotherm modeling studies. The study established the successful fabrication of a biocompatible nano-composite and its usefulness as an advanced adsorbent for fast and high removal of toxic contaminants like norfloxacin from wastewater.